Abstracts: 31st Annual Meeting of the American College of Veterinary Ophthalmologists, Montreal, Canada. October 11–15, 2000
Article first published online: 7 JUL 2008
Blackwell Science Ltd
Volume 3, Issue 4, pages 247–257, December 2000
How to Cite
(2000), Abstracts: 31st Annual Meeting of the American College of Veterinary Ophthalmologists, Montreal, Canada. October 11–15, 2000. Veterinary Ophthalmology, 3: 247–257. doi: 10.1046/j.1463-5224.2000.00153.x
- Issue published online: 7 JUL 2008
- Article first published online: 7 JUL 2008
Abstract no.: 001
Interferon treatment of idiopathic ocular granulomatous disease of collies
R. C. Riis
Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY, USA
Purpose: To assess the effectiveness of oral interferon upon Collie fibrous histiocytomas when other modalities were ineffective or intolerable. Interferons are a group of related cycloproteins forming part of the cytokines. Of the three groups of interferons designated as α, β, and γ, the product is inexpensive and easily obtained. It is manufactured by recombinant DNA technology that employs genetically engineered Escherichia coli. Idiopathic ocular granulomas, fibrous histiocytomas, nodular granulomatous episclerokeratitis, recurrent proliferative keratoconjunctivitis, and chronic granulomatous inflammations may be a disease syndrome that is one and the same in dogs. It affects the cornea, limbus, conjunctiva, episclera, nictitans, lid margins, and mucocutaneous junctions of the nose and lips. Methods: The initial case was treated with oral Interferon α2a (Roferon-A by Roche, Bazel, Switzerland), 80 IU/dog, because it was either refractory to conventional treatments or hypersensitive to medications causing a flair-up of a chronic colitis or seizures. Treatments tried prior to Interferon α2a included oral azathioprine, tetracycline and niacinamide, cimetidine, l-asparaginase, chlorambucil and prednisone as well as topical corticosteroids, subconjunctival corticosteroids, cryosurgery, and surgical debulking. Results: The lesions biopsied showed predominantly lymphocytes, plasma cells, histiocytes, and fibrocytes. After 1 month, noticeable lesion changes in size with no new lesions appearing were observed. After 2 months, the lesions had resolved and only crusty skin and alopecia remained at lesion sites. Continued use for 2 months showed normal areas where lesions had been. Interferon α2a was used alone on three other Collies with fibrous histiocytomas for 6 months; all resolved. Conclusions: Idiopathic ocular granulomatous disease of Collies has been found to be responsive to oral Interferon α2a at an empirical dose of 80 IU/dog/day for 6 months. Dose formulation: Three million IU of powdered Roferon-A is hydrated and added to 1 litre of IV Baxter 0.9% NaCl (remove 27 cc first, to account for overfill), giving 3000 IU/mL. Divide into 1½ ml aliquots to be frozen. Dispense 99 mL distilled water and 1 mL diluted Roferon into 4 ounce prescription brown bottle (30 IU/cc). Keep refrigerated; good for 1 month.
Abstract no.: 002
The relationship of hyperadrenocorticism (Cushing’s Disease) to recurrent corneal disease in dogs
T. Kotani, K. Tsuzuki, E. Uchida, S. Katoh, T. Seno, N. Ito*, Izumisawa and K. Yamashita
Department of Veterinary Surgery, Department of Veterinary Medicine, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Japan, *Yokohama University, Department of Ophthalmology, Yokohama, Japan
Purpose: This study investigated the relationship of hyperadrenocorticism (Cushing’s Disease) to refractory corneal disease. Material and Methods: The medical records of 32 cases of chronic or refractory corneal disease in dogs presented to the Rakuno Gakuen University Veterinary Medical Teaching Hospital in 1999 were examined. Complete ophthalmic examinations including behavioral observation, the PLRs, the menace reflex, tear test measurements, fluorescein and Rose bengal stains, slit lamp biomcroscopy, and indirect and direct ophthalmoscopy were used to assess vision and examine the ocular condition. All cases were measured for routine blood tests and serum cortisol levels. Sixteen cases were tested with the ACTH stimulation test, and six cases were tested with the low dose and high dose dexamethasone suppression tests. Results: The ophthalmology examinations revealed recurrent keratitis, recurrent corneal erosions by positive fluorescein staining tests (32 cases), positive rose Bengal staining tests (32 cases), fibrin in the anterior chamber, aqueous flare, conjuntival hyperemia, pannus, and decrease of tear production. Seventeen cases (53%) showed high blood cortisol concentrations and 12 cases (37%) were diagnosed with Cushing’s Disease. Twenty-four (75%) cases of corneal disease were in the Shih-tzu breed, with 12 of the Shi-tzus (70%) having Cushing’s Disease. All cases ranged in age from 3 to 15 years (mean 8 years) with 10 dogs being male. Conclusion: The presence of recurrent corneal disease in dogs may be associated with elevated systemic cortisol concentrations, especially in the Shih-tzu breed.
Abstract no.: 003
Canine corneal endothelial microscopy–a comparison of two techniques
Small Animal Hospital, Wiesbaden, Germany
Purpose: To examine the corneal endothelium of clinically normal dogs and to compare the results obtained by contact and noncontact endothelial microscopy. Methods: Fifty-one dogs presented for nonophthalmic procedures requiring general anesthesia were examined by indirect ophthalmoscopy, applanation tonometry and biomicroscopy with a hand-held slit lamp prior to specular microscopy of the corneal endothelium. Fourteen different breeds as well as mixed breeds (n = 13) were studied (Beagle n = 18, German shepherd n = 6, Miniature poodle n = 2, Boxer n = 2, German wire-haired pointer, Schnauzer, Bullmastiff, Rottweiler, Bernese mountain dog, Brandel Bracke, Yorkshire Terrier, Airedale Terrier, Akita Inu, and wire-haired Dachshund; n = 1 each). The ages ranged from 3 months to almost 15 years (3–177 months, 58.7 ± 45.2), the weight varied from 3 to 63 kg (18.9 ± 12.6). Fifty-one dogs were subjected to contact specular microscopy with a Rodenstock Biophthal endothelial microscope; 49 dogs were examined by noncontact endothelial microscopy with a Zeiss Photo Slitlamp with microscope attachment. The endothelial cell density was determined manually from photographs using a modified fixed frame method, and the results were subjected to statistical analysis using Student’s t-test. Results: The endothelial cell density as determined with the noncontact method is significantly higher in both eyes than with contact specular microscopy (OS: 2482 ± 312 cells/mm2 noncontact vs. 2402 ± 296 cells/mm2 contact, P = 0.0004, correlation 0.882; OD: 2463 ± 310 cells/mm2 noncontact vs. 2415 ± 299 cells/mm2 contact, P = 0.0153, correlation 0.9103). There was no significant difference between the right and the left eye or between males and females. The endothelial cell density decreases with age (nonlinear regression)–the decrease is greatest during the first year of life and approaches a base-line of 2298 cells/mm2 at 4 years of age–and with an increase in body weight. Conclusions: Contact specular microscopy is technically less demanding than the noncontact method and it is easier to evaluate the results morphologically. The significantly higher cell density found in this study was probably due to focusing artefacts inherent to manual focusing. Financial interest: None.
Abstract no.: 004
Examination of the normal canine corneal endothelium with a noncontact specular microscope: a comparison of shih-tzu and other breeds
R. Igarashi*, Y. Maeda*, T. Chuma*, O. Igarashi*, A. Saito† and T. Kotani†
*Kushiro Animal Hospital, Kushiro, Japan, †Triangle Animal Hospital, Tokyo, Japan, ‡Department of Veterinary Surgery, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Japan
Purpose: The incidence of corneal disease is higher in Shih-Tzu than in other breeds. Using a noncontact specular microscope, this study made a comparison of the corneal thickness and endothelial cell characteristics of Shih-Tzu with those of other breeds. Methods: Twenty-nine healthy dogs (38 eyes), 1–5-year-old (mean ± SD; 2.4 ± 1.5 years), consisting of 12 Shih-Tzu dogs (19 eyes) and 14 dogs of other breeds (19 eyes), were examined with a noncontact specular microscope to evaluate corneal thickness, mean endothelial cell density, mean cell size, and percentage of hexagonal cells in the central cornea. Noncontact specular microscopy and photography were performed with a TOPCON Medical SP2000P specular corneal endothelial microscope with the dogs in dorsoventral position under sedation. Results: Corneal thickness in Shih-Tzu was 0.4745 ± 0.0755 mm (mean ± SD), and in other breeds it was 0.5460 ± 0.0545 mm. The corneal thickness was significantly thinner in Shih-Tzu (P < 0.005). Mean endothelial cell size in Shih-Tzu was 370.26 ± 16.93μm2, and in other breeds it was 329.15 ± 15.59μm2. Endothelial cell size was significantly greater in Shih-Tzu (P < 0.001). Endothelial cell density in Shih-Tzu was 2705.3 ± 111.88 cells/mm2, and in other breeds it was 3046.0 ± 159.15 cells/mm2. Endothelial cell density in Shih-Tzu was significantly lower (P < 0.001). Hexagonal cell percentage in Shih-Tzu was 55.74 ± 14.15%, and in other breeds it was 59.89 ± 14.07%. There was no significant difference in hexagonal cell percentage between Shih-Tzu and other breeds. Conclusions: Compared with other breeds, Shih-Tzu dogs have a thinner cornea, larger endothelial cell size, and lower endothelial cell density. These results suggest that measurement of corneal thickness and morphological characteristics aids in the study of corneal disease in Shih-Tsu. Commercial interest: None.
Abstract no.: 005
Anterior capsule staining with indocyanine green for continuous curvilinear capsulorrhexis
B. S. Silverman
Complete Animal Eyecare Center, Studio City, California
Purpose: Radial tears of the anterior capsule during continuous curvilinear capsulorrhexis may occur in the inexperienced cataract surgeon. Visualization of the anterior capsule is difficult to differentiate from the mature cataract without a tapetal reflex. This technique describes an aid for visualizing and performing anterior capsulorrhexis in white cataracts. Methods: Four dogs (seven eyes) were examined with slit-lamp biomicroscopy, indirect ophthalmoscopy, applanation tonometry, complete blood count, biochemical profile and bilateral electroretinography preoperatively. All dogs had mature cataracts, lack of tapetal reflex and normal intraocular pressure. Each dog was anesthetized in a routine manner, given a neuromuscular block and placed on a mechanical ventilator. A 1.5-mm paracentesis was performed. The anterior chamber was filled with air displacing aqueous humor. 0.5 mL Indocyanine Green (ICG) 0.5% solution (270 mOsm osmolarity) was dropped on to the capsule and left for 2 min. The excess ICG was irrigated from the anterior chamber with balanced salt solution followed by viscoelastic. Continuous curvilinear capsulorrhexis was performed with utrata forceps; two handed-phacoemulsification with + 41 diopter intraocular lens placement was performed in 6/7 eyes. Patients were examined 1 day, 7 days, 14 days, 21 days and 28 days postoperatively. Each dog was evaluated for aqueous flare and intraocular pressure. Results: All seven eyes demonstrated normal capsulorrhexis without radial tears. Two + to 3 + flare was observed during the first 2 weeks postoperatively in all cases; flare resolved by day 28. Two cases required intracameral injection of Tissue Plasminogen Activator (TPA). Postoperative intraocular pressure ranged from 4 to 14 mmHg. Conclusions: Anterior capsule staining appears to be a safe and effective method of performing CCC. Excellent differentiation of anterior capsule and white cataract was seen in all cases. The technique can help the inexperienced or presbyopic surgeon perform this procedure with skill and ease. No adverse effects were noted from the use of ICG. Further studies with laser flare-cell photometry are recommended.
Abstract no.: 006
Video fluorescein angiography in raptors
R. T. Korbel*, B. Nell†, I. Walde† and P. T. Redig*
*The Raptor Center, College of Veterinary Medicine, Department of Small Animal Clinical Sciences, St Paul, Minnesota, USA, †Department for Surgery and Ophthalmology, Veterinary University, Vienna, Austria
Purpose: The aim of the present study was to adapt fluorescein angiography (FAG) to the special needs of the avian patient and to observe the distribution of the dye within the eye. Methods: FAG (fluorescein-sodium 10%, 40 mg/kg BW, administered via the superficial ulnar or jugular vein) was performed in 46 anesthetised and six nonanesthetised raptors (nine species) and documented using a high speed fundus camera. A specially designed indirect ophthalmoscope in combination with a miniaturized video camera was used to demonstrate FAG in motion. Results: Based on the differing anatomical structures, FAG in raptors showed phases markedly different from those in mammals, i.e. a filling phase (duration 4 ± 2 s) followed by a choroidal (duration in owls 10 ± 3 s, other raptors 5 ± 2 s) and a pecten phase (duration in owls 6 ± 2 s, other raptor species 3 ± 1 s), which started approximately 2 seconds after the choroidal phase, followed by leakage of the dye from the pecten into the vitreous. After a maximum of 28 h no dye could be demonstrated ophthalmoscopically. It could be demonstrated that fluorescein is ejected into the vitreous with a frequency of up to 10 times/min, independently from so-called saccadic oscillatory movements of the eye. Conclusions: The escape of dye into the vitreous in birds may be seen as a proof of the nutritional function of the pecten. The morphological basis behind this effect however, needs further (electron microscope) investigation. Beside the importance for further physiological studies, FAG in birds can be used for the diagnosis of subtle hemorrhages of the pecten and choroid, atrophy of vessels and the retinal pigment epithelium, as well as retinal detachments and other diseases of the fundus. Our results may be used as reference values for routine clinical use. Financial disclosure: Supported by the Minnesota DNR Fund and the Fund of the Veterinary University Vienna to promote foreign relations. Commercial interest: None.
Abstract no.: 007
Intraocular pressure screening as part of a routine health profile in older cats
M. M. Kroll,* P. E. Miller,† and I. Rodan*
*Cat Care Clinic, Madison, WI, USA, †Department of Surgical Sciences, School of Veterinary Medicine, University of Wisconsin, Madison, USA
Purpose: To establish normative data for IOP in aged cats in a clinic setting, and to determine the value of IOP screening as part of a routine health profile for cats (7 years of age). Methods: Tono-Pen XL tonometry was performed by trained technical staff on 538 cats (1068 eyes) as part of a routine geriatric profile recommended for all cats 7 years of age, at a large, feline-exclusive, private practice in Madison, WI from March 3, 1999 to July 26, 2000). Results: Two hundred and thirty-six were neutered males, 302 neutered females, and the mean age was 12.3 ± 2.9 (S.D. range: 7–22) years. Mean IOP OU was 12.28 ± 4.0 S.D. (median: 12, range: 4–31) mmHg. Additional measurements from 78 cats (154 eyes) a mean of 9.4 ± 3.0 (S.D.) months after the first were significantly lower (10.9 ± 4.0 S.D. mmHg, P < 0.001) than the first set of values. At the time of the first profile, 58 cats (77 eyes) had an IOP 7 mmHg. One of these cats had a cataract and presumed lens-induced uveitis, another had overt uveitis. The remaining 56 were ophthalmically normal, had iris atrophy, or had a variety of chronic metabolic disorders. After the first profile, five cats (0.9%) were presumed abnormal based on an IOP of 28 mmHg or a difference of 12 mmHg between eyes. One cat with a difference of 12 mmHg later had IOPs of 10 and 11 mmHg (false positive). One cat with IOPs of 7 and 19 had uveitis in one eye and aqueous misdirection in the other. One cat with initial IOP of 26 mmHg, anisocoria and aqueous misdirection (false negative) had an IOP of 30 mmHg 1 month later. Causes of abnormally high IOP were presumed aqueous misdirection in four cats, and a subluxated cataract in one cat. All seven cats with truly abnormal IOP (high or low) had abnormal ophthalmic examinations. Conclusion: IOP screening can be a useful addition to a routine geriatric profile in cats (7 years of age if proper technique is used and IOP values are combined with an ophthalmic exam. 1.3% (7/538) of older cats have abnormal IOP. IOP may decrease with age in cats. Commercial interest: None.
Abstract no.: 008
The effect of age on intraocular pressure in Labrador Retriever dogs
A. J. Mughannam*, C. S. Cook* and C. L. Fritz†
*Veterinary Vision, San Mateo, CA, USA, †California Department of Health Services, Sacramento, CA, USA
Purpose: To assess the degree to which intraocular pressure (IOP) changes with age during early growth of Labrador Retriever dogs. Methods: Thirty-two Labrador Retriever puppies received ophthalmic examinations for evaluation as prospective service dogs (Guide Dogs for the Blind, San Rafael, CA) (T1). All puppies were approximately 2 months of age; precise ages were known based on whelp date. The pupils were pharmacologically dilated with 1% tropicamide, then biomicroscopy and indirect ophthalmoscopy were performed. Next, 1% proparacaine was instilled and IOP was measured using a Tonopen XL. The left eye was always measured first, and measurements were always made by the same person. Measurements were recorded only if the per cent error was 5%; those readings with error higher than 5% were repeated. Ophthalmic examination was repeated approximately 1 year later (T2). Mean and standard deviation of IOP values were calculated for each eye and for the mean of both eyes at each evaluation. Differences in IOP between sex or litter groups were evaluated using Student’s t-test. Differences in IOP between T1 and T2, and between OD and OS at a given evaluation, were assessed by paired Student’s t-test. Results: The mean IOP in mmHg for OD was 14.00 and 15.19 at T1 and T2, respectively. The mean IOP for OS was 12.80 and 14.53 at T1 and T2, respectively. The mean IOP for OU was 13.40 and 14.86 at T1 and T2, respectively. IOP at T2 was statistically greater than T1 (P < 0.05). The mean difference between OD and OS at T1 was 1.16; OD was statistically greater than OS (P = 0.0003). Conclusions: Previous studies reported higher IOP in younger animals and proposed relatively increased IOP as a driving factor in globe expansion and growth; our data contradict this theory. As scleral rigidity increases with age and may affect readings obtained by applanation tonometry, this may account for the differences between T1 and T2. Interestingly, IOP for OD at T1 were statistically greater than OS. As we know of no physiologic explanation for this difference, it may reflect the normal range of variation of IOP thus decreasing the clinical significance of statistical difference between T1 and T2. Commercial interest: None.
Abstract no.: 009
Ocular biometry of canine breeds predisposed to cataracts
C. Görig, F. Wagner, A. Meyer-Lindenberg and I. Nolte
Clinic of Small Animals, School of Veterinary Medicine, Hannover, Germany
Purpose: The primary purpose of the current study with regards to measuring canine eyes preoperatively in order to individually calculate IOLs was to evaluate differences in the ocular dimensions, refraction and corneal curvature between breeds, age groups as well as gender and secondly to discover possible links between these ocular parameters. Methods: Two hundred and eighty eyes of seven different breeds predisposed to cataracts with 20 dogs in each breed were measured under general anesthesia. First keratometry was performed with an automatic hand-held keratometer (Nidek KM-500) which yielded the horizontal and the vertical radius simultaneously. Secondly, the refractive state of the examined eyes was determined by streak retinoscopy (Heine Beta 200). Lastly A-scan ultrasonography performing the immersion technique was applied on the eyes to evaluate the axial length and the intraocular dimensions of each globe. Ten consecutive keratometry and A-scan measurements were taken from each eye and the mean values were calculated. Retinoscopy was performed on each globe only once by the same examiner. The comparison of ocular refraction, the corneal radii and intraocular distances between the groups was performed with the paired t-test (P < 0.05). Results: In the present study, keratometry revealed that in every case the vertical corneal radius was smaller than the horizontal radius. Therefore, the canine cornea is of an elliptical shape. The cornea was flatter in adult dogs, male dogs and dogs of large breeds compared to the corneal curvature of juvenile, female and small breed dogs. The refractive state of the eyes of various canine breeds was found to be nearly emmetropic (–0.01 D ± 1.22) with significant differences between breeds and age groups. In addition, a significant influence of body size was assessed, with a shift towards hyperopia in large breed dogs and shift towards myopia in small breed dogs. All three intraocular dimensions, as well as the axial length of the globe were influenced by the age and body size of the examined dogs. Gender only exhibited an influence on lens thickness and axial length. The anterior chamber depth comprised 19–22%, the lens thickness 32–35% and the depth of the vitreous body 46–48% of the whole length of the globe. Body size and age influenced the proportions of the globe; however, the gender exhibited no influence. Conclusions: The dogs’ physiological ocular refraction and therefore the aimed postoperative refractive state following cataract surgery with implantation of an IOL depends on the breed and especially on the dogs’ body size. The results of the other ocular parameters also varied in a wide individual range and depended on the breed; therefore it is not adequate to provide all dogs with an implantation of an IOL with the same strength. The changes in the ocular measurement parameters with respect to age seem to follow typical growth patterns. Commercial interest: None.
Abstract no.: 010
Retrobulbar anesthesia of both bupivacaine and lidocaine for intraocular surgery in dogs
N. Kanemaki, K. Ono, T. Suga and Y. Wada
School of Veterinary Medicine, Azabu University, Japan
Purpose: Retrobulbar anesthesia of lidocaine may have a short-time action for the cataract surgery following insertion of intraocular lens in the eyes. Retrobulbar anesthesia is often used to anesthetize and elevate the eyeball for intraocular or corneal surgery. We evaluate in this study the effect of retrobulbar anesthesia of both bupivacaine and lidocaine on relaxation of external ocular muscles, stability of the eyeball, pupillary size and intraocular pressure, compared with either lidocaine or bupivacaine. Methods: Nine unilateral eyes in Shiba dogs were divided into three groups according to the random extraction method; Group 1 was administered a retrobulbar injection of both 0.5% bupivacaine hydrochloride (0.05 mL/kg) and 2% lidocaine hydrochloride (0.05 mL/kg), Group 2 was administered an injection of 2% lidocaine hydrochloride (0.1 mL/kg), Group 3 was administered an injection of 0.5% bupivacaine hydrochloride (0.1 mL/kg). Retrobulbar injection was carried out 15 min after inhalation anesthesia of isoflurane started. The conditions of retrobulbar anesthesia and intraocular pressures were assessed during general anesthesia. The Scheffe’s procedure in the analysis of variance was used statistically to compare the results. Results: External ocular muscles started to be relaxed between 5 and 20 minutes after retrobulbar injection in Group 1 and 2. Expression of muscle relaxation in Group 1 and 2 occurred earlier than in Group 3. Disappearance of muscle relaxation in Group 1 was delayed as compared in Group 2. Results of stabilities of eyeballs were mostly the same results of relaxation of external ocular muscles. No difference in groups was showed as the results of measurements of pupillary size and intraocular pressure. Conclusions: Retrobulbar anesthesia of both bupivacaine and lidocaine indicated relaxation of external ocular muscles and stability of the eyeball, which were induced as early as retrobulbar anesthesia of lidocaine, and lasted as long as anesthesia of bupivacaine alone.
Abstract no.: 11
Halothane anesthesia inhibits rhodopsin regeneration in vivo and prevents light-induced retinal damage in the mouse and rat
C. B. Keller,* C. Grimm,† A. Wenzel,† F. Hafezi,† C. Remé†
*Department of Clinical Studies, University of Guelph, Guelph, Canada, †Laboratory of Retinal Cell Biology, University of Zurich, Zurich, Switzerland
Purpose: The objective of the study was to determine whether halothane anesthesia has an effect on rhodopsin regeneration in vivo and whether this might, as a consequence, result in an altered sensitivity to light damage. Methods: Albino mice were dark adapted before they were exposed to 20 or 60 min of white fluorescent light (5000 or 13000 lux, respectively) while under halothane anesthesia (1.5%). Control mice were not anesthetized. Albino rats under anesthesia (1.8% halothane) were exposed to 3000 lux of white light for 60 min or to blue light (403 nm ± 10 nm) for 30 min. Anesthesia was stopped after light exposure and animals were kept in the dark for 24 h or in normal light-dark cycle for 10 days before they were euthanised and enucleated. Eyes were fixed in glutaraldehyde and embedded in Epon 812. TUNEL staining and DNA fragmentation analysis was performed. Rhodopsin was measured in retinas of mice either immediately after bleaching (10 min of white light (5000 lux)) or at variable times during the subsequent rhodopsin regeneration in darkness. Mice were divided into three groups: mice not anesthetized, mice anesthetized during bleaching only and mice anesthetized during and after bleaching. Results: Mice exposed to white light without anesthesia had severe photoreceptor cell death 24 h after exposure. Anesthetized mice did not show signs of light damage after 24 h and 10 days. In situ positive TUNEL staining of cell nuclei and presence of internucleosomally fragmented genomic DNA confirmed the photoreceptor apoptosis exclusively in nonanesthetized mice. Light exposure for 10 min resulted in an almost complete bleach of rhodopsin. Metabolic rhodopsin regeneration after light exposure was almost completely inhibited in anesthetized mice. Control mice regenerated rhodopsin to completion within 1 h in darkness. If halothane was stopped immediately after bleaching, rhodopsin regeneration had a 15-min delay, but was almost complete after 60 min. Rats exposed to blue light under anesthesia showed photoreceptor apoptosis while rats exposed to white light under anesthesia did not develop any damage. Conclusions: Halothane anesthesia prevents metabolic regeneration of rhodopsin after bleaching. The low amount of available rhodopsin during anesthesia only allows a small number of photons to be absorbed. Since the number of photons absorbed determines the extent of the retinal damage, halothane acts as a protective agent against photoreceptor apoptosis induced by white light. Blue light damage cannot be prevented by halothane because of an existing alternative rhodopsin source under blue light conditions. Financial disclosure: Supported by Swiss National Science Foundation; E & B Grimmke Foundation, Germany; EMDO, Switzerland. Commercial interest: None.
Abstract no.: 012
Calcium-dependent chloride channel activity in canine retinal pigment epithelia
B. H. Grahn*, N. K. Smith†, D. L. Hamilton† and G. W. Forsyth†
*Department of Small Animal Clinical Sciences, †Department of Veterinary Biomedical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5B4, Canada
Purpose: Chloride channels that might be contributing to the transmembrane potential across dog retinal pigment epithelia were investigated to determine the relative levels of expression of known chloride channels in this tissue. Methods: Eyes obtained from healthy dogs following euthanasia were transected, the sclera removed by blunt dissection, and the retina stripped off to give preparations of retinal pigment epithelium(RPE) and choroid. These RPE-choroid preparations were mounted in Ussing chambers in a Krebs Ringer buffer containing 5 mm K+ and 5 mm glucose. Transepithelial potential difference and short circuit current were recorded. The oral hypoglycemic agent glibenclamide was added to both sides of the RPE at a final concentration of 50 μM. Primary cultures of dog RPE were established by harvesting cells after a 5-minute exposure to trypsin in phosphate-buffered saline. Harvested cells were added to DMEM buffered with 20 mm HEPES, pH 7.4, supplemented with 10% fetal bovine serum and 10 ng per ml of fibroblast growth factor, and plated on Primera 35 mm culture dishes coated with mouse laminin (2.5 μg/cm2). Total RNA from 250 cells was reverse transcribed at 50° using Superscript reverse transcriptase (GIBCO), and cDNA corresponding to 125 cells was amplified in PCR with primers specific for the cystic fibrosis transmembrane regulator protein (CFTR) or a calcium-dependent chloride conductance protein (pCLCA1). Results: Glibenclamide addition (50 μM) to dog RPE mounted in Ussing chambers caused a consistent decrease in short circuit current. Glibenclamide is recognized as a relatively specific inhibitor of CFTR. However, we have recently shown that chloride efflux from mouse fibroblasts expressing pCLCA1 is significantly inhibited by glibenclamide. Cultured dog RPE cells expressed relatively high levels of the pCLCA1 calcium-dependent chloride conductance channel mRNA. Expression of CFTR was undetectable at the number of PCR cycles (30) showing strong banding of pCLCA1 cDNA. Conclusions: The expression of the pCLCA1 chloride conductance channel in dog RPE, and the inhibition of short circuit current in dog RPE by inhibitors of pCLCA1 chloride conductance, indicate that this calcium-regulated chloride channel may be important in establishing the transepithelial potential difference involved in ion and fluid transport across this tissue. Financial disclosure: Supported by a grant from the Canadian Cystic Fibrosis Foundation to GW Forsyth. Commercial interest: None.
Abstract no.: 013
Ocular and serum pharmacokinetics of intravenous cefazolin in the dog
N. C. Whelan, R. J. Richardson, J. M. Kinyon, A. Pace, P. M. Welch and C. A. Brienza
College of Veterinary Medicine, Iowa State University, Arnes, IA, USA
Purpose: The purposes of this trial were to calculate the intraocular pharmacokinetics of intravenous (IV) cefazolin (CFZ) in the dog in the normal and inflamed eye and to correlate intraocular and serum CFZ concentrations. Materials and methods: Twenty-one beagle and mixed breed dogs were allocated to one of six groups for sampling at ½, 1, 1½, 2, 4 or 6 h post-treatment. After general anesthesia, intraocular inflammation was created in one eye by aqueous paracentesis. Dogs were dosed over 10 min with 20 mg/kg of cefazolin sodium (100 mg/mL) IV. A single aqueous, vitreous and serum sample was taken at the designated sampling interval. Samples were analyzed by bioassay using Bacillus subtilis ATCC 6633 in Difco Antibiotic no. 1 medium. Results: Aqueous protein concentrations confirmed intraocular inflammation in the paracentesed right eye. The highest intraocular CFZ concentrations were 100 mcg/mL at ½ hour in the inflamed eye. A second peak occurred at 2 h concurrently associated with an increase in anterior chamber protein concentration. Aqueous CFZ concentrations remained above 50 mcg/mL for 4 h and ranged between 58 and 100% of the serum concentrations. Vitreous CFZ concentrations in both eyes were only detectable where there was hemorrhage associated with sampling. Conclusions: In this model, the intraocular inflammation following aqueous paracentesis would be reasonably representative of the inflammatory conditions during and following cataract surgery. For beta-lactam antibiotics it is the duration of antibiotic exposure which is important for efficacy. The average length of bilateral canine cataract surgery is between 2 and 3 h. Therefore it is recommended that animals should be redosed at the end of cataract surgery to ensure that a therapeutic level is maintained for at least an additional 4 h. Financial disclosure: Supported by the College of Veterinary Medicine, Iowa State University. Commercial interest: None.
Abstract no.: 014
Three intravitreal cyclosporine (CsA) implants in horses with naturally occurring recurrent uveitis
B. C. Gilger*, D. A. Wilkie†, P. Ashton†, T. Smith†, G. J. Jaffe§ and J. B. Allen*
*Comparative Ophthalmology Research Laboratories, North Carolina State University, Raleigh, NC, USA, †Department of Veterinary Clinical Sciences, The Ohio State University, Columbus, OH, USA, ‡Controlled Delivery Systems, Inc, §Duke University Eye Center, Durham, NC, USA
Purpose: CsA intravitreal implants have been shown to be safe (Cutter et al. IOVS 1999; 40(4):S; Gilger et al. Vet Ophthalmol, 2000, 3(2/3): 105–110) and effective in reducing ocular inflammation (Gilger et al. Vet Immunol Immunopathol 2000, in press) in experimental uveitis in horses. The purpose of this study was to determine the effect of intravitreal CsA implants on episodes and recurrences of inflammation in horses with naturally occurring equine recurrent uveitis (ERU). Methods: Horses with documented cases of ERU that had frequent recurrent episodes of uveitis, or were progressing despite appropriate mediation, were selected for this study. Inclusion criteria included an ERG b-wave amplitude over 100 μV, lack of significant cataract formation (< 10% of lens), and no vision threatening ocular complications (e.g. retinal detachment, severe retinal degeneration, posterior synechia). CsA devices (2 or 4 μg/day release rate) were implanted through a sclerotomy, 1 cm posterior to the dorso-temporal limbus. After surgery, oral NSAIDs and topical antibiotic were used for 10 days. Reexaminations and ERG were performed at 1, 3, 6 and 12 months postimplantation. Ophthalmic changes, number of recurrent episodes, amount of medication required, and vision were recorded. Results: The first 12 horses (14 eyes) received the 2 μg/day implant and the subsequent14 (14 eyes) received the 4 μg/day implant. The only complication noted as a result of the surgical implantation occurred in one horse, that had complete hyphema. Eight of 14 eyes had recurrent episodes of uveitis with the 2μg/day implant; however, fewer medications were needed to control the uveitis than prior to the implant. No significant change was noted on the mean ERG b wave amplitude. The most common complication was progression of cataract, which was observed in 5 of 14 eyes, all of which had preexisting cataract formation. Because of this finding, horses selected for implantation with the 4 μg/day implant had minimal to no cataract formation. Two of 14 horses with the 4 μg/day implant developed recurrent episodes. Only one horse developed cataract formation with the 4 μg/day implant. ERG amplitude was maintained. Mean overall follow-up was 12.8 months. Conclusions: The CsA devices were well-tolerated with no complications from the implants themselves. These results indicate that this device, especially the 4 μg/day device, may be a safe and important tool for the long-term treatment of naturally occurring chronic uveitis, such as ERU. Funding sources: State of North Carolina, Veterinary Equine Research Center Foundation, NIH grants #EY11364 (JA), EY09106 (GJ), 5P30EY05722 (Duke Core). Commercial interest: None.
Abstract no.: 015
Effect of topical 0.005% latanoprost on normal eyes of horses
K. A. Diehl*, A. M. Willis*, S. Hoshaw-Woodard†, I. Kobayashi*, M. Vittuci* and M. Schmall*
*College of Veterinary Medicine and †The Biostatistics Program, The Ohio State University, Columbus, OH, USA
Purpose: To determine the effect of topical 0.005% latanoprost (XalatanTM, Pharmacia & Upjohn) on the intraocular pressure (IOP) of normal equine eyes, and to establish the frequency of clinically significant side-effects of drug administration. Methods: Twenty adult horses of both genders with clinically normal eyes were acclimated to the procedure of applanation tonometry prior to measurement recording. IOP was then recorded daily in both eyes at 6 time points (7, 9 and 11 am; 3, 5, and 7 pm) during 3 periods: days 1–2: baseline, days 3–7: treatment, and days 8–9: follow-up. During the treatment period only, 0.1 mL (5 μg) of latanoprost was instilled in the inferior conjunctival cul-de-sac of one randomly chosen eye of each horse every 24 h, following the 7 am-IOP recording. The following parameters were recorded in addition to IOP during the treatment and follow-up periods: presence and degree of miosis, and the presence or absence of epiphora, blepharospasm, blepharedema, and aqueous flare in either eye. Recorded IOP of eyes at each time point was an average of three tonometry readings for that eye. Mixed linear regression models were used to compare the IOP of each eye (treated and untreated), for each gender, at each time period (baseline; treatment; follow-up), for each horse. Adverse events were evaluated using frequencies and histograms. Results: There were no differences between the treated and untreated eyes at baseline, when controlling for gender. When compared to baseline, IOP in the treated eye was reduced by an average of 1.03 mmHg in males, and by 3.01 mmHg in females during the treatment period. When controlled for gender, on average, the treated eye had 2.3 mmHg lower IOP than the untreated eye during the treatment period. IOP increased 1.68 mmHg per day during the follow-up period; however, when controlling for both the time and gender effect, the treated eye still had an average of 2.4 mmHg-lower IOP than the untreated eye. Miosis occurred in the treated eye of all horses, and was moderate to marked in 77% of horses, with the peak effect occurring between 4 and 15 h post drug administration. Epiphora, blepharospasm and blepharedema were noted in 57%, 42%, and 12% of treated eyes, respectively, 2–15 h following drug administration. Aqueous flare was not observed in treated eyes at any time point. There was no gender effect on adverse effects recorded. Conclusions: While IOP was reduced with q 24 h dosing of latanoprost over the short-term, the frequency of prostaglandin-related adverse events during the treatment period was high. As recurrent uveitis appears to be a risk factor for glaucoma in horses, topical latanoprost may potentiate prostaglandin-mediated inflammatory disease in affected horses. Commercial interest: None.
Abstract no.: 016
Effect of single and multiple doses of 0.2% brimonidine tartrate in the glaucomatous beagle
K. N. Gelatt and E. O. MacKay
Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL, USA
Purpose: To evaluate the effect of topical 0.2% brimonidine on intraocular pressure (IOP), pupil size (PS), and heart rate (HR) in single- and multiple-dose studies in Beagles with inherited primary open angle glaucoma. Methods: IOP, PS, and HR were measured in eight Beagles with moderate primary open angle glaucoma at 8 and 10 am, noon, and 2 and 5 pm. Drug and nondrug eyes were assigned using a random lock design. Single dose studies included one drop of placebo (0.5% methylcellulose), and 0.2% brimonidine (Alphagen, Allergan, Irvine, California) once (8 am), twice (8 am and noon), and three (8am, noon, and 4 pm) times daily for 1 day in one eye and the opposite eye served as the control. For the multiple dose study, 0.2% brimonidine was administered in one eye twice (8am and 5 pm) or three (8 am, noon, and 5 pm) times daily, and the IOP, PS, and HR measurements were at 8 am, noon, and 5 pm. Statistical comparisons between drug groups included control (nondrug) and treated (placebo/0.2% brimonidine) eyes. Results: The mean ± SEM decline in the diurnal IOP for the control and glaucoma eyes were 3.4 ± 4.7 mmHg, and 5.4 ± 2.8 mmHg, respectively. The PS (3–4 mm) and HR (100–110) levels were relatively consistent. The mean ± SEM declines in diurnal IOP after 0.2% brimonidine drops once, twice, and three time daily were 6.4 ± 3.5 mmHg, 8.0 ± 6.1 mmHg, and 9.75 ± 8.1 mmHg, respectively. Although there were trends, most declines in IOP were not significant. Some dogs were more responsive than others. PS reduced 2 through 8 h to about 2.7 ± 0.3 mm post drug administration. HR decreased by about 12%. The daily mean ± SEM changes in diurnal IOP after brimonidine (0.2%) instilled in one eye twice daily for 4 days were 5.0 ± 1.3 mmHg, 5.7 ± 1.3 mmHg, 1.4 ± 3.3 mmHg, and 4.9 ± 1.3 mmHg, respectively. With 0.2% brimonidine instilled three times daily for 4 days, the mean ± SEM diurnal IOP changes were 6.75 ± 1.3 mmHg, 2.4 ± 1.5 mmHg, + 1.2 ± 2.7 mmHg, and 1.4 ± 1.8 mmHg, respectively. In both studies the PS and HR reduced daily but nearly regained control levels the following day 8 am measurements. The reduction in daily HR was 12% to 18%. Conclusions: The commercial 0.2% brimonidine tartrate solution demonstrates a trend in reducing IOP but not at statistical significance. Both PS and HR changes suggested drug activity for several hours. In contrast to apraclonidine in dogs, 0.2% brimonidine produces miosis rather than mydriasis. HR is reduced with uniocular 0.2% brimonidine installations. In the treatment of the canine glaucomas topical 0.2% brimonidine must be supplemented with additional IOP lowering drugs. Financial disclosure: Supported in part by the Jaqua Foundation and the Gwathmey-Adams Laboratory for Vision Research. Commercial interest: None.
Abstract no.: 017
Modified Ahmed anterior shunt to the parotid duct in the glaucomatous beagle
K. N. Gelatt and E. O. MacKay
Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL, USA
Purpose: Develop a valved anterior chamber to parotid duct shunt and test its efficacy in glaucomatous Beagles in the advanced stages of the disease. Methods: The study was divided into: (1) in vitro saline perfusion studies to determine valve function; (2) feasibility study of the prototype valve implantation in four dogs; and (3) long-term study with the production model monitoring clinical signs, tonometry and tonography. Results:In vitro saline perfusion studies indicated valve function of a modified Ahmed implant (VS-1 and VS-2) with opening pressures (12–22 mmHg), closing pressures (8–18 mmHg) at flow rates (4.2–12 μl/min). The posterior aspect of the Ahmed implant was either grooved or removed, and placed in a 0.04–0.007 mm-reinforced silicone envelope with 0.3 mm (ID)×0.6 mm (OD) anterior chamber and drainage tubing. The prototype AC-PD implants ranged from 12–14×14–20 to 3–4 mm thick, and could be primed. The production implants were rigid and smaller (8 mm d×2 mm). Surgical implantation of the prototype valves placed the device below the zygomatic arch through a skin incision directly dorsal of the parotid duct and apposed to the masseter muscle. The parotid duct, cannulated with 2–0 nylon suture, was isolated, transected, and the proximal position ligated with 2-4-0 nylon sutures. The distal portion was cannulated with 2–3 cm of the implant’s drainage tubing. The anterior chamber tubing was directed to the orbit subcutaneously using a hubless 14 g hypodermic needle. With extra length tubing in the retrobulbar space, the tubing was inserted into the anterior chamber beneath a limbal-based scleral and conjunctival flaps. Surgical refinements with the smaller implant included location to the temporal muscle caudal of the orbit and a silicone strip in the retrobulbar space to stabilize the AC tubing. Postsurgical results with the prototype device indicated immediate lowering of IOP (preoperative IOP: 33.5 ± 8.5 mmHg; postoperative:16.8 ± 0.3 mmHg); tubing egress from the anterior chamber occurred with one eye 6 days after surgery; the priming was associated with peri-valve infection that required removal of three of four devices; but one device continues to function 8 months later. Postoperative results with the production model indicated immediate lowering of the IOP (22.0 ± 9.7 mmHg) with occasional spikes (treated with intracameral 25–50 μg tissue plasminogen activator; corticotsteroids; NSAIDs; and CAIs) with 4 months follow-up. Tonography of patent shunts indicated ‘C’ values in excess of 0.8 μl/min/mmHg. Conclusion: This procedure requires a valved implant, control of intraocular inflammation, and appears promising. Financial disclosure: Supported by the Jaqua Foundation, New World Medical, and the Gwathmey-Adams Laboratory. Commercial interest: None.
Abstract no.: 018
Fundus and ERG study in a group of three whippet dogs from a colony of whippets where progressive blindness in male dogs had been observed
B. Clerc, S. Chahory and W. Beltran
Service d’Ophtalmologie, Ecole Nationale Vétérinaire, 7, avenue du Général de Gaulle, 94704 Maisons-Alfort Cedex, France
Purpose: Follow up of three whippets obtained by crossing a blind male and two clinically healthy females from the same colony. Methods: Regular eye examinations were performed on the three dogs. ERG was performed regularly using a standardized protocol for 1 year. Results: Fundus examination remained normal throughout the period of examination. The ERGs were modified in the three dogs. The a wave amplitude remained normal; a latency was normal (14.4 milliseconds). b wave amplitude decreased with time (10 folds with photopic stimulation); b latency remained within the limits of 27 to 37 milliseconds when measurable. Conclusions: The main modification of ERG was the slow decrease in b wave amplitude. The results of this experiment suggest that an hereditary retinopathy was responsible for the blindness observed in the adult dogs of the colony studied.
Abstract no.: 019
Ocular transmissible veneral tumor (TVT) in dogs: four cases
L. T. Faragone*, A. M. V. Safatle*, A. Morales*, M. S. Lowen†, M. C. Martins† and P. S. M. Barros*
*College of Veterinary Medicine, University of São Paulo, Brazil, †Escola Paulista de Medicina, UNIFESP, Brazil
Purpose: Neoplasia affecting the extraocular tissues may spread to these tissues by hematogenous or lymphatic routes, extension from adjacent tissues or the optic nerve, or, in the case of TVT, by whole tumor cell implantation on a mucous membrane. In this report we describe the clinical, microscopic, and immunohistochemical features of ocular TVT in four dogs. Methods: Four mixed-breed, middle-aged dogs (two males, two sexually intact females) were admitted to the Ophthalmic Service at the Veterinary Hospital at University of São Paulo in 1997 with tumors involving the eyelids, conjunctiva, nictitating membrane, globe or orbit. Three of these cases presented with genital TVT. The masses were excised surgically and examined by histologic and immunohistochemical tests. Results: Macroscopically, the masses had an irregular surface, ulceration and necrosis. The microscopic examination in all four cases revealed granular, eosinophilic, proteinacous material admixed with small aggregates of round cells with eosinophilic cytoplasm and round nuclei, and atypical mitotic figures. By immunhistochemistry, all the samples were negative to antibodies for vimentin, cytokeratin, LCA, HMB 45, and Pan B and Pan T cell. Conclusions: The microscopic, immunohistochemical, and clinical features of these cases were diagnostic for TVT. The pathogenesis remains uncertain due to the negative staining for vimentin, cytokeratin, LCA, HMB 45 or Pan B and T cell markers. Commercial interest: None.
Abstract no. 20
Antioxidant status of aqueous humor of dogs submitted to extracapsular lens extraction
P. S. M. Barros*, C. F. Padovani*, V. V. Silva† and S. B. M. Barros†
*School of Veterinary Medicine, University of São Paulo, Brazil, †School of Pharmaceutical Sciences, University of São Paulo, Brazil
Purpose: To evaluate the antioxidant activity of aqueous humor after extracapsular lens extraction. Methods: The study was conducted in 14 mixed breed dogs, weighing about 10.0 Kg. Animals were examined under slit lamp biomicroscopy, applanation tonometry (Tonopen) and indirect ophthalmoscopy. One eye was submitted to conventional extracapsular lens extraction and the fellow eye was the control. Samples of aqueous humor were obtained by anterior chamber paracentesis before and at day 1, 2, 3, 7 and 15 after surgery. Total antioxidant status was evaluated as the capacity of aqueous humor to inhibit free radicals generation by an aqueous solution of ABAP(2,2-azobis(2-amidoopropane)chlorine. Ascorbic acid concentration was measured by HLPC with UV detection. Protein content was determined with biuret reagent. Statistical analysis was performed by anova followed by the Tukey–Kramer test. Results: Protein concentration showed a 30-fold increase after 24 h of the surgery. These levels were maintained for the following days and returned to normal at day 7. Total antioxidant capacity was reduced until day 3 and at day 7 it was equal to control. The ascorbic acid levels had a similar pattern that only returned to control values at day 15. Conclusions: Considering the importance of ascorbic acid concentration in aqueous humor for the maintenance of the antioxidant status of the anterior segment of the eye, the decrease of antioxidant defenses suggest that the surgical procedures promote an oxidative stress condition to the eye. Financial disclosure: Supported by FAPESP grants n°. 98/2939–0, 98/7964–3, 99/5112–2. Commercial interest: None.
Abstract no.: 021
Ultraviolet irradiation up-regulates telomerase activity in lens epithelial cells
C. M. H. Colitz*, C. J. Lam* and M. C. McGahan†
*Louisiana State University School of Veterinary Medicine, Baton Rouge, LA 70803, USA, †North Carolina State University College of Veterinary Medicine, Raleigh, NC 27606, USA
Purpose: We previously reported that telomerase activity was present in lens epithelial cells (LEC) and that it increased with age and with cataractous changes. In the present study, we investigated the acute and chronic effects of direct irradiation (UVB) on telomerase activity in LEC. Methods: In the acute UV experiments the anterior aspects of freshly dissected lenses were irradiated with UVB for 5 (n = 16), 20 (n = 12), 40 (n = 10), and 60 s (n = 9). Thirteen lenses were nonirradiated controls. Lenses were then placed anterior aspect down in DMEM/F12 media with 10% fetal bovine serum for 24 h (5 second group) or 5 h (20, 40, and 60 second group) at 37 °C and 5% CO2. Following incubation, lens capsules with adherent LEC were dissected from the lenses. Telomerase activity was analyzed as previously published using TRAP-ELISA kit (Roche/Boehringer Mannheim, Germany). In the chronic UV experiments the anterior aspects of freshly dissected lenses were irradiated with UVB for 2 s every day for 7 days (n = 8), 5 s every day for 7 days (n = 8), 2 s every other day for 7 days (n = 6) and 5 s every other day for 7 days (n = 9). The capsules were then turned anterior side down in DMEM/F12 media with 10% fetal bovine serum while being incubated. The day following the last ultraviolet B treatment, lens capsules with adherent lens epithelial cells were harvested for protein extraction and telomerase activity assessment. Control group (n = 8) was incubated in media anterior side down for the entire study. Media was changed every third day. Results: Lenses irradiated for 5 s had an increased telomerase activity when compared to controls (0.305 ± 0.056 vs. 0.164 ± 0.030; P<0.05). The lenses irradiated for 20 s and 60 s had a significant increase in telomerase activity when compared to controls (0.389 ± 0.159, 0.270 ± 0.111 vs. 0.236 ± 0.090, respectively). The lenses irradiated for 40 s did not have a significant increase in telomerase activity when compared to controls (0.223 ± 0.117 vs. 0.236 ± 0.090). All four chronically irradiated groups had increased telomerase activity when compared to controls (0.190, 0.224, 0.223, 0.223 vs. 0.160). Conclusions: We had originally speculated that the age-related increase in telomerase activity found in LEC might be due to chronic UV exposure. In the present study we found that direct ultraviolet irradiation increased telomerase activity in LEC. Financial disclosure: Funded by NIH grant EY00414-02. Commercial interest: None.
Abstract no.: 022
Immunocytochemical staining for telomerase and TRT in lens capsule whole mounts
C. M. H. Colitz and C. J. Lam
Louisiana State University School of Veterinary Medicine, Baton Rouge, LA 70803, USA
Purpose: Telomerase and TRT function in the nucleus to replace lost telomeric ends during DNA replication in cells with unlimited proliferative capacity like lens epithelial cells (LEC) and tumor cells. The regulation of these proteins is not thoroughly understood. In the present study, we investigated the general cellular and regional locations of telomerase and TRT proteins in LEC. Telomerase and TRT are part of the telomerase ribonucleoprotein complex and TRT is the catalytic subunit of this complex that activates telomerase. Methods: The anterior capsule was separated from the underlying lens fiber mass, gently placed on a Probe-On Plus slide cell side up and dried for 3 min at room temperature. The capsule mount was fixed for 10 min in 4% paraformaldehyde. This was followed by a 5-minute wash in 3X PBS and then 1X PBS until staining. Immunocytochemical staining of LEC adherent to the lens capsules was performed using standard avidin-biotin-peroxidase complex techniques with diaminobenzidine as the chromogen and hematoxylin as the counterstain. Commercially available antibodies to telomerase and TRT were used at a dilution of 1:500. Negative controls were lens capsular specimens incubated with normal goat serum instead of primary antibody. Results: Immunostaining for telomerase was positive in 75% of all LEC on the capsules. Immunostaining was most prominent in the equatorial region with approximately 75% of positively staining cells having both nuclear and cytoplasmic staining and 25% having only nuclear staining. In the germinative region, approximately 75% of positively stained cells had both nuclear and cytoplasmic immunostaining while the other 25% of cells interspersed among the doubly stained cells had staining only in the nucleus or cytoplasm. In the central region, approximately 60% of cells immunostained mainly in the cytoplasm. Immunostaining for TRT was positive in 80% of all LEC on the capsules. In the germinative and equatorial regions, approximately 70% of cells immunostained in both the nuclei and cytoplasm, approximately 20% of the cells had only cytoplasmic staining; the remaining 10% of cells had only nuclear staining. Approximately 20% of cells in the central region stained positively for TRT and the immunostaining was localized primarily to the cytoplasm. Conclusions: We have found both telomerase and TRT to be present both in the nucleus, as expected, and in the cytoplasm, where they are made. The large number of cells with cytoplasmic immunostaining may indicate that telomerase and TRT may be stored in the cytoplasm for future use under critical conditions. To our knowledge this is the first intracellular localization of telomerase and TRT in any cell type. Financial disclosure: Funded by NIH grant EY00414-02. Commercial interest: None.
Abstract no.: 023
Topographic variation in retinal function in a bifoveate bird (Buteo jamaicensis)
G. A. Abrams*, J. N. VerHoeve† and C. J. Murphy*,†
*Department of Surgical Sciences, School of Veterinary Medicine, †Department of Ophthalmology and Visual Science, School of Medicine, University of Wisconsin-Madison, USA
Purpose: To characterize topographic variations in retinal function in a bifoveate bird, the red tailed hawk (Buteo jamaicensis). Methods: Two young mature (less than 4 years old based on iris pigmentation) red-tailed hawks were determined to have normal ocular exams by slit lamp biomicroscopy and indirect ophthalmoscopy. The hawks were sedated with xylazine and ketamine and dilated with an intracameral injection of atricurium. Fundus photography, optical coherence tomography (OCT), and multifocal electroretinography (MERG) was performed. The hawks were refracted and corrected for distance for the MERG. The MERG stimulus was a 241 element unstretched array of hexagonal patches, which subtended the central 110° of the retina. Results: Fundus photography captured both fovea in each image verifying their normal appearance. OCT confirmed that the central (nasal) fovea was steeper than the temporal fovea. The vitreous was found to lack no attachment to the retina in the foveal region. The amplitude of the MERG from regions corresponding to the two fovea were extremely large compared to the primate. Foveal amplitudes exceeded 10 μV in each bird compared to the primate foveal region of 100 nV, a difference of 2 log units greater sensitivity. The region of increased sensitivity had distinct waveform characteristics in a large comingled area of higher sensitivity creating a ‘hyper-macula’. The waveforms for the two foveae were distinct with the central (nasal) fovea having a significantly larger a-like wave than the temporal fovea. Conclusions: The vitreous nonattachment may facilitate delivery of nutrients to the retina from the pecten. The convexiclivate foveae may improve acuity by acting as a telescopic lens. The photopic MERG response is larger than that found in any reported species. Waveform differences for the two fovea suggest distinct retinal circuitry. These findings suggest the two fovea operate together to create a very large area of increased sensitivity, challenging the visual trident theory wherein the two fovea function as separate, isolated entities. Financial disclosure: Supported in part by the Veterinary Optometric Society. Commercial interest: None.
Abstract no.: 024
Refractive error in llamas and alpacas
A. M. Willis*, D. O. Mutti†, D. E. Anderson*, M. K. Jeandervin†, J. J. Walline2 and S. E. Andrew†
*College of Veterinary Medicine and †College of Optometry, The Ohio State University, Columbus, OH, ‡College of Veterinary Medicine, University of Florida, Gainseville, FL, USA
Purpose: To determine the refractive state of the llama and alpaca using streak retinoscopy. Methods: Retinoscopy was performed in dim light on 50 llamas (Lama glama) and 45 alpacas (Lama pacos) following pupillary dilation with 1% cyclopentolate. Cycloplegic refractive error was measured in each eye in both the horizontal (H) and vertical (V) meridians. Data were analyzed by species, gender (female, male and castrated male), age, and eye using multivariate anova. Results: Mean age of animals examined was 5 years (range: 6 months to 18 years). Mean ± SEM refractive error was −0.60 ± 0.16 H/–1.11 ± 0.17 V for llamas and −0.12 ± 0.15 H/–0.07 ± 0.16 V for alpacas. The species effect was significant (P = 0.02 H/P = 0.001 V). Controlling for the species effect, a gender effect was also significant. Females were more myopic (−0.81 ± 0.17 H/−0.89 ± 0.19 V) than intact males (0.05 ± 0.16 H/−0.23 ± 0.18 V) or castrated males (–0.15 ± 0.29 H/−0.52 ± 0.33 V). There was no effect of eye or age on refractive error within species, and no interaction between eye, age, or gender within species. Conclusions: Llamas in this population demonstrated a mild myopia and astigmatism while alpacas approached emmetropia. Females were slightly more myopic than males. The reason for the apparent species and gender effect on refractive state is currently unknown, but may be associated with both ocular anatomical size differences (i.e. axial length and corneal curvature) as well as behavior. Commercial interest: None.
Abstract no.: 025
Corneal endothelial cell density, corneal thickness, and corneal diameters in normal alpacas
S. E. Andrew,* D. E. Anderson,† and A. M. Willis†
*College of Veterinary Medicine, University of Florida, USA, †College of Veterinary Medicine, The Ohio State University, USA
Purpose: To determine corneal measurements including endothelial cell density, thickness, and horizontal and vertical diameters in eyes of normal alpacas. Methods: Alpacas with normal anterior and posterior segment ophthalmic examinations were sedated with xylazine. The animals were placed in sternal recumbency and a noncontact specular microscope (Topcon SP-2000P, Topcon America, Paramus, NJ, USA) was used to determine corneal endothelial cell density (ECD) in the central portion of the cornea. Corneal thickness (CT) was measured by ultrasonic pachymetry (DGH500, DGH Technology Inc., Exton, PA, USA) in five areas (central, dorsal, ventral, medial, and lateral) with peripheral measurements made approximately 5 mm from the limbus in the clear portion of the cornea. Horizontal and vertical corneal diameters were measured with a Jameson caliper. Data were analyzed by multivariate anova to determine the influence of age, gender, and eye on ECD, CT, and corneal diameter. Pearson correlation coefficients were also generated. Animal age was categorized as < 60 months or > 60 months. Results: Fifteen alpacas were used. Animals ranged from 22 to 204 months of age, with a median of 30 months. Nine were males (median 38 months, range 22–88 months) and six were females (median 89 months, range 23–204 months). Mean (± SEM) central ECD (cells/mm2) values were 2066 (± 131) cells/mm2 for right eyes and 2446 (± 210) cells/mm2 for left eyes. The only significant variable affecting ECD was age (P = 0.004), where increased age was strongly correlated with decreased ECD (r2 = 0.58). Mean (± SEM) CT in five areas of 27 eyes (14 left, 13 right) was 587± 5 μm. No significant effects of eye, gender, or age were detected in CT; however, there was a trend toward increased CT with decreased ECD. Mean (± SEM) horizontal corneal diameter in 29 eyes (15 right, 14 left) was 30.5 ± 1.1 mm. Mean horizontal diameter was 30.4 (± 0.3) and mean vertical diameter was 22.1 (± 0.3) in the right eyes. Mean horizontal diameter was 30.4 (± 0.3) and mean vertical diameter was 22.0 (± 0.4) in the left eyes. There was no effect of age, gender, or side on corneal diameter. Conclusions: Endothelial cell density decreased significantly with increased age. There was no effect of gender on ECD once age was removed as a compounding factor. There were no significant differences between right and left eyes from the same alpaca. There were no effects of gender, age, or side on CT or corneal diameters. Commercial interest: None.
Abstract no.: 026
Arcus lipoides corneae in cuban tree frogs (Osteopilus septentrionalis) and its relationship to serum lipids
C. B. Keller,* C. Shilton,†. D. Smith,†. G. Crawshaw,‡ and E. Valdes†
*Department of Clinical Studies, †Department of Pathobiology, University of Guelph, Guelph, Ontario, ‡Toronto Zoo, Toronto, Ontario, Canada
Purpose: Lipid keratopathy is the most commonly reported corneal disease in amphibians. The objective of this study was to experimentally create arcus lipoides corneae in Cuban tree frogs and to document the association of the disease with serum lipids. Methods: Sixty-five Cuban tree frogs were collected from the wild. Fifty-two were kept in captivity for the feeding experiment. Thirteen frogs and later an additional 17 frogs were used as wild controls. For the first 4½ months all frogs received a diet of regular crickets. After 4½ months the frogs were divided into two dietary groups: one received regular crickets and the other received high cholesterol crickets. Frogs were weighed every 1–3 months and received five ophthalmologic examinations. Frogs were bled and euthanised following 17 months of captivity. Wild controls were bled and euthanised after their arrival. Total protein, triglyceride and cholesterol were measured using an Ektachrom DT analyzer. HPLC was used to separate the lipoproteins. Histopathology was performed on eyes and other organs. Oil red O, Sudan black B and Schultz stain were applied to frozen sections of cornea. Results: The first case of arcus lipoides corneae occurred in a female frog after 13 months in captivity. In the subsequent 4 months, an additional 5/11 males and 11/35 females developed the disease. Crystalline corneal infiltrates started at the limbus and progressed axially. Frogs with arcus lipoides corneae had elevated serum total cholesterol (27.3–19.8 mmol/L) and LDL cholesterol (17.8–18.9 mmol/L) compared to unaffected captive frogs (16.5–20.4 and 9.0–7.6 mmol/L, respectively). The disease was more prevalent in frogs on high cholesterol diet. Frogs on this diet had higher serum total cholesterol (34.1–15.2 mmol/L in females and 22.8–14.8 mmol/L in males) than frogs on the diet of regular crickets (12.3–8.7 mmol/L in females and 10.4–3.1 mmol/L in males). Captive frogs on both diets had higher serum total cholesterol than wild frogs (3.1–2.1 mmol/L in females and 5.3–2.6 mmol/L in males). Elevations in serum cholesterol in captive frogs were due to relative elevations of VLDL cholesterol and LDL cholesterol as compared to HDL cholesterol. These elevations were significantly higher in captive females than males. Conclusions: Arcus lipoides corneae can be experimentally induced in male and female Cuban tree frogs. Frogs on a diet of high cholesterol crickets are more susceptible to developing the disease than frogs on a diet of regular crickets. Captive frogs on both diets have elevated serum cholesterol compared to wild frogs. Financial disclosure: Supported by Association of Amphibian and Reptile Veterinarians and Toronto Zoological Society. Commercial interest: None.
Abstract no. 027
Ocular disorders of captive non-domestic felids
T. J. Kern,* M. B. Glaze†
*College of Veterinary Medicine, Cornell University, Ithaca, NY, USA, †School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA, USA
Purpose: The goals of this study were to survey veterinary ophthalmologists with experience in diagnosis and treatment of captive exotic felids, tabulate the results, and investigate the age and species incidence of reported ocular disorders. Methods: Veterinary ophthalmologists were invited to complete a survey of ocular disorders of captive nondomestic felids which included signalment, origin (breeder, zoo, private individual, circus), detailed description of ocular abnormalities, treatments, outcome and follow-up. For tabulation, abnormalities were categorized as malformations, adnexal lesions, lens disorders, retinal disorders, and other. Lesion types, age, and species affected were enumerated within each category were. Results: Ten ophthalmologists from the United States (n = 8) and United Kingdom (n = 2) contributed information regarding 47 animals of 10 species ranging in age from 3 months to 10 years; age was not reported for all animals. The most frequently reported species were lion, snow leopard, tiger, and Scottish wildcat. The most frequent ages at diagnosis were 6 months (n = 22) and 1–6 years (n = 11). Lesion frequency distribution from highest to lowest was lens lesions (n = 24: 23 cataract, 1 traumatic lens luxation; 8 species), retinal disorders (n = 8: 6 feline central retinal degeneration, 2 other; 3 species), malformations (n = 5; 4 species), adnexal lesions (n = 3; 1 species), and other (n = 4; 3 species). Conclusions: Ocular abnormalities were diagnosed in captive individuals of a wide variety of threatened, endangered, and nonthreatened nondomestic feline species. Cataract and central retinal degeneration were the most frequent lesions. Commercial interest: None.
Abstract no.: 028
The effect of oral L -lysine on the course of feline herpesvirus conjunctivitis
J. Stiles,* W. Townsend,* Q. Rogers† and S. Krohne*
*Purdue University School of Veterinary Medicine, West Lafayette, IN, †UC Davis, School of Veterinary Medicine, Davis, CA, USA
Purpose: To evaluate the effect of oral l-lysine on the course of experimentally induced feline herpesvirus conjunctivitis. Methods: Eight healthy adult cats with normal ocular exam were included in a 3-week study. Unilateral conjunctivitis was induced in all cats by placing 50 μL of feline herpesvirus grown in cell culture (1.8×108 TCID-50/mL) in the conjunctival sac. Beginning the day of infection, four cats received 500 mg l-lysine twice daily, and four cats received a placebo. The study was blind to the investigators. Daily scores were recorded for conjunctival hyperemia, chemosis, blepharospasm, ocular discharge and fluorescein staining. Samples for virus isolation were taken every 3rd day from the affected eye and the throat. CBC and chemistry panels were evaluated before and after the study. Samples for plasma lysine and arginine levels were drawn weekly throughout the study period. The two groups of cats were compared using the Friedman test. Results: Cats receiving l-lysine had a statistically significant (P < 0.001) reduction in severity of disease compared to cats receiving placebo. Plasma lysine levels averaged 200–300 nmol/mL, a 2–3 fold increase over baseline, while arginine levels were unaffected. Conclusions: 500 mg of oral l-lysine BID was well tolerated in all cats and may be beneficial in treating herpesvirus conjunctivitis. Financial disclosure: Supported by Ohio Animal Health Foundation. Commercial interest: None.
Abstract no.: 029
Clinical effects of cyclosporine on the conjunctiva and mucus discharge in a canine KCS model
C. P. Moore,* J. B. McHugh,† J. G. Thorne* and T. E. Phillips†
*College of Veterinary Medicine, †Division of Biological Sciences, University of Missouri, Columbia, MO, USA
Purpose: To test the effects of topical cyclosporine (CsA) on the conjunctiva and conjunctival mucus production independent of its lacrimostimulant effect in a canine KCS model. Methods: Keratoconjunctivitis sicca was induced bilaterally in six dogs following removal of orbital and nictitans lacrimal glands. Two weeks after induction of KCS, either 2% CsA or vehicle was applied twice daily to each operated eye until 6 weeks post-KCS induction. Eyes of three additional unoperated control dogs were treated twice daily with vehicle only. STTs were performed at baseline and twice weekly until the end of the study in 6 weeks. Clinical parameters (conjunctivitis and mucus discharge scores) were recorded as part of an expanded study whereby incisional biopsy specimens of ventral fornix conjunctiva were collected for histochemistry and morphometry prior to gland removal (baseline) and at 2, 4 and 6 weeks after KCS induction. At each sampling time, eyes were photographed and color images were subsequently graded for degree of conjunctivitis and characteristics of ocular discharge. Results: Lacrimal gland removal resulted in induction of KCS in dogs by 2 weeks, with mean STT values of 5 mm/min occurring for operated eyes compared to 22.5 mm/min prior to surgery and 22.9/min in unoperated control eyes at 2 weeks and, in operated dogs, STT values remained low during the 6 week study. In the KCS groups, conjunctival inflammation scores were less in CsA-treated eyes than in vehicle-treated KCS eyes at 6 weeks (4 weeks post-treatment). Compared to vehicle-treated operated dogs at 2 weeks (pretopical treatments), mucus discharge scores increased in the two KCS groups with the CsA-treated KCS eyes having decreased mucus discharge scores at 4 weeks and returning to baseline at 6 weeks. Conclusions: Severity of conjunctivitis and mucus discharges were decreased in KCS eyes treated with CsA. Given the nature of this KCS model, conjunctival responses were not associated with lacrimogenic effects. Results of this study indicate that CsA exerts an anti-inflammatory effect on the conjunctiva and may affect the quality of conjunctival mucin independent of lacrimal response. These effects are associated with increased intraepithelial mucin stores as previously described for this canine KCS model. Proprietary interests: None. Support: NIH-NEI EY10594.
Abstract no.: 030
Effect of itraconazole therapy on the histopathologic findings in the eyes of dogs with blastomycosis
D. V. H. Hendrix, P. N. Bochsler and B. W. Rohrbach
College of Veterinary Medicine, University of Tennessee, Knoxville, TN, USA
Purpose: To determine the effects of systemically administered itraconazole on the degree of intraocular inflammation, and on the number of Blastomyces dermatitidis organisms, and their viability and budding in histologically prepared specimens from the eyes of dogs with confirmed blastomycosis. Methods: All globes were stained with hematoxylin and eosin and Gomori’s methenamine-silver. Numeric scores were assigned for degree of inflammation, number of organisms, and viability. For portions of the statistical analyses, scores for several tissues were combined into a total score for an anterior section (AS) and a posterior section (PS). The scores from eyes of dogs treated with itraconazole were compared with those of dogs not treated. We also compared scores from eyes of dogs treated with itraconazole for 1–14, 15–28 and 29–63 days. A nonparametric one-way analysis of variance procedure was used to compare scores among treatment groups. Results: Forty-three eyes from 35 dogs with blastomycosis were included in the study. Thirty-two eyes were enucleated surgically and 11 were removed at necropsy. Lens rupture with associated intralenticular leukocytes was seen in 15 of 33 (45%) eyes; evidence of cataract was seen in 27 of 34 (79%) eyes. There was no significant difference in the degree of inflammation between the AS or the PS among treated and nontreated groups, or among the three groups given itraconazole for different periods of time. There was a significant difference (P = 0.04) in the degree of inflammation between the group treated with itraconazole for 29–63 days and the two groups treated for 1–14 and 15–28 days in the PS. There was no significance difference in the number of organisms in the eyes of dogs treated verses those untreated with itraconazole,or among the three groups given itraconazole for different periods of time in either the AS or PS. Although not statistically significant, fewer organisms were seen in the 15–28 day treatment group and more organisms were seen in the group treated for 29–63 days. There was no significant difference in the viability of organisms or presence of budding in the PS among eyes from dogs treated and untreated with itraconazole. The number of eyes with organisms exhibiting viability or budding were too few for a meaningful statistical analysis in the AS group. Conclusions: No significant difference was found in number, viability, or budding of Blastomyces dermatitidis organisms between eyes from dogs that were treated, when compared with those that were untreated, with itraconazole. These data suggest that eyes unresponsive to therapy, that continue to have opaque media or inflammation, should be enucleated. Financial disclosure: Supported by Companion Animal Fund, University of Tennessee. Commercial interest: None.
Abstract no.: 031
Intracameral carbachol is superior to topical latanoprost in preventing post-operative intraocular pressure rises after cataract extraction in dogs
C. M. Stuhr,* P. E. Miller,† and D. Covitz*
*Animal Eye Clinic, Wilton CT, †Department of Surgical Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, USA
Purpose: We previously have demonstrated that intracameral administration of 0.5 mL of 0.01% carbachol is superior to a saline placebo at preventing the transient, marked increases in intraocular pressure (IOP) that may occur following phacoemulsification lens extraction (PLE) in dogs (JAVMA 1998, 212: 1885–1888). Here we compared the ability of intracameral carbachol to that of topical 0.005% latanoprost at preventing these marked postoperative IOP rises. The potential negative effects of postoperative miosis and increased uveitis were also evaluated. Design: Prospective, randomized, masked clinical trial. Methods: Twenty-eight adult dogs undergoing elective unilateral or bilateral PLE were randomly assigned into two groups with 14 dogs per group. The groups were (1) PLE with one drop of 0.005% latanoprost topically at the conclusion of surgery (18 eyes) and (2) PLE with 0.5 mL of 0.01% carbachol intracamerally at the conclusion of surgery (23 eyes). All eyes received an intraocular lens. Intraocular pressure and pupil size was evaluated at 3 and 6 h after surgery, and aqueous flare was evaluated at 6 h. Aqueous flare, pupil size and IOP were also measured one week following surgery. Results: Intracameral carbachol was significantly superior (P = 0.016, Fischer’s Exact Test) to topical latanoprost in preventing IOP rises above 27 mmHg at 3 h postoperatively (0/14 dogs experienced a rise with carbachol vs. 6/14 with latanoprost). Median pupil size was 2 mm at 3 h postoperatively in both groups. Differences in aqueous flare or posterior synechiation were not noted between groups by a masked observer at any time period in this study, or when compared to historical controls receiving only saline. No deleterious effects of immediate postoperative miosis were noted. Intraocular pressure, pupil size and motility were normal in all dogs by 1 week except for one miotic pupil in one eye treated previously with latanoprost. Conclusion: Intracameral 0.01% carbachol (0.5 mL) was more effective at preventing an acute postoperative rise in IOP after PLE than 1 drop of 0.005% latanoprost. Neither agent caused an increase in aqueous flare when compared to each other or to historical saline controls. Complications associated with postoperative miosis were not observed. Commercial interest: None.
Abstract no.: 032
Long-term release of antibiotic to the ocular surface of horses by a ciprofloxacin-containing drug delivery device–preliminary evaluation
B. C. Gilger,* V. Valentine,* M. Papich,† B. Wang† and J. B. Allen*
*Comparative Ophthalmology Research Laboratories, †MPP Department, ‡Department of Chemistry, North Carolina State University, Raleigh, North Carolina, USA
Purpose: PVA/EVA/silicone-coated drug reservoir-type devices have been shown to be effective in the long term delivery of a variety of medications intraocularly, including cyclosporine, dexamethasone, fluorometholone, and gancyclovir. Recently, our laboratory has demonstrated the effectiveness of this type of device to deliver cyclosporine to the vitreous of equine eyes. The purpose of this study was to determine if a similar device could be used to deliver therapeutic levels of a drug to the surface of the eye for an extended period of time. Methods: Ciprofloxacin powder (15 mg) was compressed into a custom-built 3 mm tablet die. Each pellet was coated with several layers of polyvinyl alcohol, allowed to dry overnight, and inserted into a 2-mm diameter (lumen) silicone tube. Flow holes were made into the silicone tubing to allow tears and fluid into the lumen. The amount of PVA coating and number and size of silicone flow holes were modified to control drug delivery. A 3-0 nylon suture was used to anchor the implant. The completed device was treated at 104 °C for one hour. Drug delivery over time was assayed by measuring release of drug after 1, 3, 6, 12, 18, and 24 h at 37 °C. The remaining drug in the 24-h implants was assayed, which predicted duration of drug delivery. Six normal horses had the final prototype device implanted into the ventral conjunctival cul-de-sac of both eyes. The horses were examined days 1–5, 7 and 14 days after implantation. During each examination, 100 μl of tears was collected to determine drug concentration (HPLC). At the end of the study, the devices were explanted and remaining drug was assayed. Results:In vitro studies suggested that the device delivered therapeutic levels of ciprofloxacin with first order release. The predicted length of the delivery with a 15-mg device was approximately 14 days, based on the remaining drug in the reservoir. Mean concentration of ciprofloxacin in equine tears was 35.4 ± SD 22.8 μg/mL (24 h; n = 5); 27.4–18.1 μg/mL (72 h; n = 4); 22.68–5.1 μg/mL (7 days; n = 2); 34.03 μg/mL (14 days; n = 1). Conclusions: Therapeutic levels of ciprofloxacin were delivered to the tear film of the eye with the drug delivery system. The devices were very well tolerated with no signs of irritation or discomfort in normal horses. This device may be useful for the long-term treatment of bacterial keratitis in horses and eliminate the need for lavage catheters or owner compliance in difficult to treat horses. This device also may be useful in Zoo animals or avian patients with bacterial keratitis that cannot be treated frequently with eyedrops. Support: State of North Carolina, Veterinary Equine Research Center Foundation. CR: Commercial interest: None.
Abstract no.: 033
Ocular and serum pharmacokinetics of intravenous doxycyline in the dog
N. C. Whelan, R. J. Richardson and J. M. Kinyon
College of Veterinary Medicine, Iowa State University, USA
Purpose: The purposes of this trial were to calculate the intraocular pharmacokinetics of intravenous (IV) doxycycline (DOX) in the dog in the normal and inflamed eye and to correlate intraocular and serum doxycycline concentrations. Methods: Twenty Beagle and mixed breed animals were allocated to one of six groups for ocular and serum sampling at ½, 1, 1½, 2, 4 or 6 h post-treatment. Following general anesthesia, intraocular inflammation was created in one eye by aspirating 0.1 mL of aqueous humor. Dogs were dosed IV over 30 min with 10 mg/kg of doxycycline hyclate (10 mg/mL) diluted in 60 mL of lactated ringers. A single aqueous, vitreous and serum sample was taken at the designated sampling interval. Samples were analyzed by bioassay using Bacillus cereus ATCC11778 in Difco Antibiotic no. 1 medium. Results: At 0.5 h, aqueous DOX concentrations were greater than 6.8 mcg/mL in both the inflamed and normal eye. Aqueous concentrations remained above this level for the 6-h duration of the trial. Serum aqueous concentrations peaked at 6.2 mcg/mL at 0.5 h and declined slowly to 5.7 mcg/mL at 6 h. Aqueous doxycycline concentrations remained above the serum concentrations for the duration of the trial. Vitreous DOX concentrations were only slightly less then those in the aqueous humor and rose more slowly to a maximum of 6.9 mcg/mL at 6 h in both eyes. Conclusions: In this model, the intraocular inflammation following aqueous paracentesis would be reasonably representative of the inflammatory conditions during anterior uveitis associated with Rickettsial infection. Doxycycline is a lipophilic antibiotic used to treat ocular Rickettsial infections. In this trial, the level of intraocular inflammation had no bearing on the DOX concentrations reached in the aqueous and vitreous humor. It is expected that these concentrations reached in the anterior and posterior uvea would be therapeutic for at least 6 h following IV administration. Further work is required to identify if inhibitory levels are maintained at this level over the recommended 24-h dosing interval. Financial disclosure: Supported by the College of Veterinary Medicine, Iowa State University. Commercial interest: None.
Abstract no.: 034
Artificial meshwork (MESH), a new concept for the treatment of glaucoma in the dog: a pilot study of tolerance and efficacy
J. P. Jégou,*,† J. M. Legeais,‡ M. Savoldelli,‡ B. Clerc,† and G. Renard†
*Animal Eye Clinic, 39 rue Rouelle Paris 15e, †Department of Ophthalmology, Ecole Nationalle Veterinaire d’Alfort, 94700 Maisons-Alfort, ‡Department of Ophthalmology, Hotel Dieu Hospital Paris 4e, France
Purpose: To study the tolerance and efficacy of a new polytetrafluoroethylene (ePTFE) device, MESH, in the treatment of glaucoma in dogs. Several previous studies have demonstrated that this device is well tolerated and effectively lowers intraocular pressure (IOP) in normal rabbit eyes. Methods: The implantation is performed under general anesthesia using sodium thiopental and isofluorane. A 5-mm conjunctival incision is made 6 mm posterior to the limbus at the supero-temporal quadrant. The conjunctiva and Tenon’s capsule are dissected towards the limbus, and a corneoscleral stab incision is then made 0.5 mm posterior to the limbus with a 3.2-mm wide keratome. With microsurgical forceps, the head of the MESH implant is inserted through the incision into the anterior chamber, and the tail is positioned in the subconjunctival space. The conjunctiva is closed with 8/0 Vicryl, and topical dexamethasone and gentomycin are used postoperatively. The cases selected for study here were buphthalmic, nonvisual eyes, with IOP above 50 mmHg. Medical treatment for the glaucoma was continued and only one of the eyes was implanted in the same dog. Results: Seven eyes were implanted and all eyes developed a mild anterior uveitis that resolved within several days following surgery. Five of 7 cases had control of IOP between 13 and 34 mmHg at the last examination (2 and 6 months postoperatively), and further surgical intervention, such as a prosthesis or enucleation, was not necessary. One case developed some degree of extrusion of the device 3 months postoperatively after a period of IOP control, and in one case the device failed to control IOP and required placement of an intrascleral prosthesis. In this case, a fibrotic membrane encapsulated the implant in the subconjunctival space. In all cases, the intraocular tolerance was considered to be very good. Statistical analysis was not applied due to the low number of cases. Conclusions: The use of this artificial meshwork may be applicable in the surgical treatment of canine glaucoma. The ePTFE biomaterial appears to be well tolerated in the anterior chamber. The development of fibrosis around the conjunctival aspect of the device may be improved with use of antimetabolites (mitomycin or 5 fluorouracil). Development of a less reactive biomaterial than MESH, such as a composite biomaterial may also lessen the conjunctival and Tenon’s capsule fibrosis and encapsulation of the device. Commercial interests: None. Supported by F.C.I. 20, bd Gallieni, BP 111, 92134 Issy-Les-Moulineaux, France. C.
Abstract no.: 35
Measurement of chondroitin 4- and 6-sulfates in the normal equine corneal stroma by capillary electrophoresis
D. J. Biros, D. E. Brooks, M. P. Brown and K. A. Merritt
Department of Small and Large Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainsevill, FL, USA
Purpose: The goal of this study was to determine the regional distribution of the glycosaminoglycans chondroitin 4- and 6-sulfates (Δdi4s and Δdi6s) in the normal equine corneal stroma using capillary electrophoresis (CE). Methods: Corneas were collected within 24 h of death from 22 normal eyes of 11 equine necropsy specimens at the University of Florida Veterinary Medical Teaching Hospital. Isolated samples from the superficial, middle, and deep strata of both the central and peripheral corneas were frozen at −70 °C until tissue analysis. Using the enzyme chondroitinase ABC, corneal samples were tested for levels of unsaturated disaccharides Δdi4s and Δdi6s in each zone. Measurements made with CE were compared to known standards of Δdi4s and Δdi6s. Ratios of Δdi6s to Δdi4s in the different areas were calculated, and the average values from the six different regions of the cornea were statistically compared. Results: The Δdi6s/Δdi4s values were significantly lower in the deep and middle zones (P < 0.0001 and P = 0.001, respectively) when compared to the superficial zone of the combined central and peripheral corneal samples. In the central cornea, the deep and middle zones had significantly lowerδdi6s/Δdi4s values (P = 0.0004 and P = 0.0002, respectively) than the superficial zone. In the peripheral cornea, the deep zone had significantly lower Δdi6s/Δdi4s values when compared to the superficial and middle zones (P = 0.023 and P = 0.0001, respectively). In the deep zone, the peripheral region had significantly lower Δdi6s/Δdi4s values than the central zone (P = 0.025). Conclusions: Chondroitin 6-sulfate is present at significantly lower levels than chondroitin 4-sulfate in the deep and middle central, and the deep peripheral cornea. Regionally, differences in the distribution of Δdi4s and Δdi6s provides information for the initial understanding of the role of glycosaminoglycans in health, disease, and wound repair of the equine cornea. Financial disclosure: Supported in part by University of Florida College of Veterinary Medicine Resident Research Fund. Commercial interest: None.
Abstract no.: 036
Use of the rat model of oxygen-induced retinopathy as a relevant model of ocular angiogenesis
D. P. Bingaman, K. A. Hudson and M. A. Kapin
Ocular Angiogenesis Program, Retina/Degenerative Diseases Research, Alcon Research, Ltd, Fort Worth, Texas, USA
Purpose: To establish the rat model of oxygen-induced retinopathy (OIR) as a test system to define preclinical drug candidates for the treatment of angiogenesis-dependent ocular diseases, such as exudative age-related macular degeneration and proliferative diabetic retinopathy. Methods: Nine pregnant female Sprague-Dawley rats gave birth at 22 (1 day’s gestation, and selected mothers and their pups were immediately placed into separate oxygen chambers and exposed to one of two exposure profiles for 14 days. Remaining mothers and pups were kept in room air for 20 days postpartum and then euthanized. For the standard profile, neonatal pups were mixed together and then randomly separated so that each mother had 16 pups, and atmospheric oxygen was modulated between 50% and 10% every 24 h, beginning with 50% oxygen. At 14 days postpartum, the mothers and pups were removed from the oxygen chambers and returned to room air for 6 days and then euthanized. The other exposure profile (named ‘Double 50’) was conducted similarly with two major exceptions. First, the pups were not randomized to 16 pups per mother; and secondly, on days 10–11 postpartum, the oxygen level was maintained at 50% for the entire 48 h. Then on day 12 postpartum, the oscillating 10–50% 24-h cycle was resumed through to day 14, at which time all rats were placed into room air for 6 days and then euthanized. The retinas from all rat pups were harvested, fixed in buffered formalin overnight at 4 °C, and then stained as whole mounts via an ADPase technique to highlight the vascular endothelium. Digital images were acquired and a computerized analysis system was used to allow clockhour measurements for preretinal neovascularization (NV); i.e. each clockhour out of 12 available per retina was assessed for the presence or absence of preretinal NV. The median number of NV clockhours was determined for each rat, such that individual retinas were not used as independent data points because of the potential bias between right and left eyes within a given animal. Nonparametric statistical analyses were used to define whether a difference existed between the two oxygen-exposure profiles, as well as the room-air group. P 0.05 was considered significant. Results: Using the Kruskal–Wallis One Way anova, a significant increase in preretinal NV was observed using the Double 50 profile (median NV clockhours = 6) compared to the standard profile (median NV clockhours = 2.5) or to room-air controls (median NV clockhours = 0)(P < 0.001). Conclusions: The Double 50 oxygen exposure profile can be used to provide a reproducible and measurable angiogenic response in the neonatal rat retina. This model may be useful for testing the efficacy of a variety of antiangiogenic agents. E.
Abstract no.: 037
The effects of a 1.5 Tesla magnetic field on intravitreous metallic foreign bodies in rabbits
C. L. Cullen,* E. J. Kendall,† K. M. Colleaux,‡ and B. H. Grahn*
*Departments of Small Animal Clinical Sciences, Western College of Veterinary Medicine, and †Medical Imaging, Royal University Hospital, University of Saskatchewan, ‡Department of Ophthalmology, Saskatoon City Hospital, USA
Purpose: The objectives of this study were to determine if (1) small intravitreous ferromagnetic foreign bodies (FBs) are sufficiently mobile in a magnetic field, to induce acute injury, and (2) if the length of time from implantation of the intravitreous FB affects this mobility. Methods: The study population consisted of 20 New Zealand White rabbits. The rabbits were anesthetized. A 3-mm×0.72 mm magnetic foreign body (MFB) was surgically implanted into the vitreous of the right eye; a nonmagnetic foreign body (NMFB) with the same dimensions was placed intravitreally in the left eye. On day 0 (FB implantation) and day 30 all rabbits underwent computed tomography (CT) prior to, and immediately following, 30 s of exposure to a 1.5 Tesla magnetic field. The FB location on CT images was determined from the angle between and distance from orbital and ocular landmarks, respectively. Pre- and postmagnetic field exposure FB angles and distances were statistically compared on, and between, days 0 and 30. Ophthalmic examinations and fundic photography were performed weekly throughout the trial. At 31 days, rabbits were euthanized; all globes were harvested and processed for light and scanning electron microscopy (SEM). Results: There were no significant differences among angle or distance measurements for MFBs or NMFBs following exposure to the magnetic field on days 0 or 30, nor were there temporal effects of these measures between days 0 and 30. Ophthalmic examinations revealed dorso-ventral movement of both MFBs (n = 18) and NMFBs (n = 12) within the vitreous over 30 days, vitreous degeneration (n = 3 MFB; n = 2 NMFB), focal retinal tear and detachment (n = 1 MFB), retinal hemorrhage (n = 5 MFB; n = 2 NMFB), and vitreous hemorrhage (n = 1 NMFB). SEM revealed erythrocytes and intravitreous fibroblasts adjacent to the FBs. Conclusions: All particles remained mobile, even for a short period of time. Microscopic examination was employed to determine if the magnetic field induced sufficient torque to cause ocular pathology. Magnetic field-induced movement of the ferromagnetic particles was no greater in magnitude or orientation than that which occurred with the nonsusceptible particles. The dorso-ventral FB movement observed over time was most likely due to vitreous liquefaction observed ophthalmoscopically. The mild focal vitreous hemorrhage and fibrosis were related to the presence of the MFBs and NMFBs. Vitreous degeneration and hemmorhage, and focal retinal hemorrhages were consistently in proximity to the FBs. The pathologic findings are clinically significant and support a temporal effect. Removal of offending FBs of this size with vitrectomy may prevent pathologic alterations. Financial disclosure: Supported by The Earl Clifford Vincent Bequest, College of Medicine, University of Saskatchewan. Commercial interest: None.
Abstract no.: 038
Equine recurrent uveitis (ERU): occurrence of immuno-globulins in the uvea, aqueous humor and vitreous
J. C. Eule,* B. Wagner,* E. Deegen,† W. Drommer† and W. Leibold*
*Department of Immunology, †Clinic for Horses, ‡Department of Pathology of the Veterinary School of Hannover, Germany
Purpose: Autoaggressive immune mechanisms and infections, particularly leptospirosis, are discussed controversially as two possible causes of ERU. The aim of this study was (a) to investigate occurrence, concentrations and distribution of different immunglobuline (Ig) isotypes in eyes affected with ERU and (b) to examine the binding of these antibodies to ocular structures as a hint for antibody-mediated mechanisms in the pathogenesis of ERU. Methods: We examined 30 eyes of healthy horses and 41 eyes of ERU-affected horses. Occurrence and distribution of Ig isotypes (total Ig, IgGa, IgGb, IgGc, IgG(T) (IgM) in the aqueous humor, vitreous and serum were investigated by ELISA. Moreover, Igs (total Ig, IgGa, IgGb, IgGc, IgG(T), IgA (IgM) were monitored in ocular tissue by immune histology. To examine the binding of serum and intraocular antibodies to ocular tissue, we incubated serum and vitreous of healthy and ERU-affected horses on ocular tissue of healthy and ERU-affected donors. Results: All Ig isotypes studied and especially IgM were significantly increased (P > 0,05) in the aqueous humor and vitreous of ERU-affected eyes. Furthermore, the ratio of the intraocular Ig isotypes compared to those in the autologous serum revealed a shift or even an inversion of the IgGa/IgGb ratio in affected eyes, which was not observed in healthy eyes. In contrast to healthy eyes in ERU-affected eyes we demonstrated Ig in the non pigmented epithelium of the ciliary body and the plexiform and granulated layers of the retina by immune histology. Ig positive cells were exclusively found in lymph follicles of the uvea and the non pigmented epithelium of ERU-diseased eyes. Immune histologically, in contrast to vitreous and serum from healthy horses and even serum from ERU-affected donors, antibodies from the vitreous of ERU-affected eyes recognized structures in ocular tissue of healthy eyes (nonpigmented epithelium of the ciliary body and retina). Conclusion: In the ERU-affected eye significant increased Ig levels could be detected. It was shown that exclusively intraocular antibodies from diseased eyes recognize ocular tissue structures. This would be a prerequisite for initiating antibody mediated autoaggressive reactions resulting in destruction of ocular structures in ERU. Financial disclosure: In part supported by the Fährhof Foundation (Sottrum/Germany).
Abstract no.: 039
Systemic manifestations of vitamin E deficiency in canine rped (CPRA)
G. J. McLellan,* R. Cappello,† I. G. Mayhew,‡ R. Elks,† P. Lybaert,† C. Watté,† D. L. Moore,† and P. G. C. Bedford†
*Veterinary Medical Teaching Hospital, University of California, Davis, †Royal Veterinary College, University of London, London, ‡Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh
Purpose: A primary deficiency of vitamin E has been described in RPED-affected dogs. In addition to the retina, major target organs for vitamin E deficiency include the nervous system and skeletal and smooth muscles. Generalized systemic abnormalities have not been reported previously in association with RPED. The aim of this study was to identify any concurrent clinical and pathological abnormalities, which might be related to the vitamin E deficient state, in RPED-affected dogs. Methods: A retrospective and prospective study identified 15 English cocker spaniels with plasma vitamin E deficiency (< 2 μg/mL; normal 95% confidence interval = 15–25 μg/mL) which presented to the Royal Veterinary College, University of London in a 3-year period from 1996 to 1999. In each case, general physical, and thorough ophthalmologic and neurologic examinations were performed and blood samples obtained for routine hematology and biochemistry. Additional investigations conducted included estimation of plasma creatinine kinase (CK) level (n = 7); electromyography (EMG) and measurement of motor nerve conduction velocities (MNCV) for the ulnar and sciatic nerves (n = 4); thoracic and abdominal radiography (n = 1); brain magnetic resonance imaging (n = 1), and cerebrospinal fluid analysis (n = 1). Necropsy, general histopathology and neuropathology were completed in two cases which were euthanized, and brain tissues obtained for comparison from four neurologically normal dogs of similar age. Results: No signs of cardiovascular or significant neurological disease were evident in any case. No hematological or biochemical abnormalities were detected, apart from elevation in plasma CK in two dogs. Megaesophagus was diagnosed radiographically in one dog which had a history of regurgitation. Eleven of the 15 dogs examined demonstrated clinical signs of neurologic dysfunction which included ataxia (8/15), proprioceptive deficits (11/15), altered spinal reflexes (9/15) and muscle weakness (5/15). Abnormal EMG findings consisting of fibrillation potentials and positive sharp waves were recorded in two of the four dogs tested. MNCVs and amplitudes were within normal canine reference ranges. Necropsy and histopathology demonstrated striking intestinal lipofuscinosis (1/2). Neuropathology revealed central neuronal fiber degeneration with prominent neuroaxonal dystrophy, particularly within the sensory relay nuclei of the brainstem, in both dogs. Conclusion: In addition to ocular disease, RPED-affected Cocker spaniels may demonstrate other generalized clinical signs and pathological lesions, particularly affecting the neuromuscular system. Financial disclosure: Supported by the Guide Dogs for the Blind Association & Friskies (Nestec) Research. Commercial interest: None.
Abstract no.: 040
Effect of vitamin E deficiency in horse retinas
R. C. Riis and T. J. Divers
Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY, USA
Purpose: This report contrasts the retinal pigment epithelium (RPE) of a blind phthisical eye to the visual eye of the same horse made vitamin E deficient and developing equine motor neuron disease (EMND). Methods: A 16-year-old, 526.5 kg male castrated horse was pathologically evaluated after 2 years on a low vitamin E diet. The horse was purchased 1 year prior to the start of the research diet with a blind-phthisical right globe and a normal visual left eye. The deficient diet allowed no exposure to fresh grass. This horse was 1 of 10 horses fed at least one-year-old grass hay containing 35 IU/kg vitamin E ad lib, plus four pounds sweet feed with less than 16 IU/kg vitamin E, and 800 p.p.m. CuSO 4 as a pro-oxidant. Results: The serum vitamin E levels of the horse in the report in μg/mL were: 1.51 (4/2/97), 1.02 (5/29/97), 0.77 (11/7/97), 0.43 (1/28/98), 0.75 (5/8/98), 0.23 (11/9/98), 0.18 (6/2/99), 0.24 (7/19/99). Euthanasia was performed with the horse showing clinical signs of EMND and histological examination confirmed EMND. Lesions found in the central nervous system were typical of EMND and include bilateral neuronal chromatolysis and glial scarring in the brain stem motor nuclei (V, VII, and XII) and in the ventral gray column of the spinal cord with secondary moderate Wallerian degeneration of the cranial nerves, ventral spinal nerves, and peripheral nerves (femoral and radial). The ocular pathology of the left eye was limited to the RPE accumulation of ceroid lipopigment while the right eye phthisical globe RPE showed hypertrophied cells without lipopigment. Ceroid lipofuscin in the RPE had been found previously in all eyes of EMND horses (naturally occurring and experimental). Conclusions: EMND can be reproduced by feeding horses diets deficient in vitamin E with or without supplemental pro-oxidants. The lesions obtained are consistent with the naturally occurring disease. This report is one of many of horses experimentally given EMND, but it was singled out for its unique pathological ocular manifestations. Accumulations of lipopigment within the RPE apparently requires an intact functioning retina. Acknowledgement: Funded by Morris Animal Foundation Grant 30835.
Abstract no.: 041
Subcapsular epithelial plaques during canine cataractogenesis: immunohistochemical evaluation of 67 samples
C. Giudice,* L. Mertel† and G. Cammarata*
*Istituto di Anatomia Patologica Veterinaria e Patologia Aviare, †Istituto di clinica chirurgica veterinaria e radiologia, Università degli Studi di Milano, Italy
Purpose: To evaluate the transforming lens epithelial cells (LECs) in the subcapsular plaques developing during spontaneous cataractogenesis. Methods: Sixty-seven capsular specimens of cataractous lenses obtained during ICCE and ECCE procedures from dogs of different breed, sex and age, were evaluated. Forty-four whole capsules and 23 anterior capsules were examined. Five lenses from necropsied dogs served as normal controls. Alcohol, 100% -fixed, and paraffin-embedded samples were sectioned and stained with H & E, PAS, von Kossa and Mallory. Immunohistochemical staining was performed to localize vimentin, α SM-actin, AE1/AE3 cytokeratin and γ crystallin.*Results: In 27 specimens posterior epithelial migration was the only detectable alteration. In 40 samples anterior, posterior and pre-equatorial subcapsular plaques at different stages of development were present. Histologically, early plaques were characterized by multilayered, spindle cells, occasionally with fiber differentiation, and a small amount of eosinophilic amorphous material lining empty spaces between cells. More mature plaques consisted of few flattened cells with scanty cytoplasm, embedded in abundant ground substance. The capsule was multifocally thrown into folds. Oldest plaques were composed by thick extracellular material in which cells were no longer recognizable. Plaques might include remnants of degenerated fibres occasionally calcified. Boundaries between capsule- and newly deposed extracellular matrix was shaded and a continuous layer of elongated epithelial cells laid between the plaque and the cells of superficial cortex. Vimentin was expressed by normal LECs and by posteriorly migrated cells of cataractous lenses. Anti γ crystallin antibody was detected in normal lenses in pre-equatorial cells, differentiated fibers and occasionally in migrated cells of cataractous lenses. α SM-actin was normally detected in pre-equatorial and equatorial lens cells and intensely stained posteriorly migrating cells. The cells in subcapsular plaques stained strongly with antivimentin, anti-SM-actin and anti γ crystallin antibody. Anti cytokeratin failed to stain any LEC from normal or cataractous lenses. Conclusions: Cells in subcapsular plaques expressed the same cytoskeletal proteins as normal LECs, suggesting that LECs during cataractogenesis undergo a morphological modification (to a spindle feature) and produce an increased amount of ground substance but they don’t become fibroblasts or myofibroblasts. The epithelial nature of canine subcapsular plaques seems to be strengthened by the γ crystallin expression in these cells. Therefore we believe that the definition ‘subcapsular epithelial plaques’ is more adequate to identify these lesions than the expression ‘fibrous metaplasia’. (*kindly provided by Dr J. Samuel Zigler Jr. NEI Bethesda Maryland). Commercial interest: None(no conflict).
Abstract no.: 042
A retrospective analysis of non-lymphomatoid intraocular metastasis in dogs and cats
T. Kobayashi,* R. Peiffer Jr.,† J. A. Render† and W. C. Carlton§
*North Carolina State University, College of Veterinary Medicine, Raleigh, NC 27606, USA, †University of North Carolina, Chapel Hill, NC 27514, USA, ‡Michigan State University, College of Veterinary Medicine, East Lansing, MI, 48824–1314 USA, §Purdue University, West Lafayette, IN, 47907–1248, USA
Purpose: There are several single case reports of metastatic, nonlymphomatoid intraocular tumors in dogs or cats. The purpose of this study was to determine the incidence and histopathological features of metastatic nonlymphomatoid intraocular tumors in a series of cases. Materials: Information of metastatic intraocular tumors was obtained from two institutions†,‡ for the period of January 1981 through December 1996. Records were reviewed for all dogs or cats with histopathological confirmed nonlymphomatoid metastatic intraocular tumors. A total of 12 dogs and 15 cats (16 globes) had intraocular metastasis. The intraocular lesion was evaluated for (1) tumor type (2) intraocular anatomical involvement (3) presence of preiridal fibrovascular membrane (PIFM) (4) intraocular hemorrhage and (5) inflammatory protein and cell infiltration. Histopathological evidence of retinal detachment, keratitis, cataract and secondary glaucoma were also evaluated. All criteria were categorized (0) to (+++) depending on the severity of the lesion. Results: (1) Dogs: median age was 10 years. Mix breed dogs were the most common (6/12). Male to female ratio was 3: 4. The left eye was more frequently involved than the right eye (OS: OD = 7: 3, the side was unknown in two patients). The most common tumor type was undifferentiated carcinoma (n = 8) following by hemangiosarcoma (n = 2), adenocarcinoma (n = 1) and osteosarcoma (n = 1). (2) Cats: median age was 9.5 years. Most are DSH or DLH cats (10/15). Male to female ratio was 3: 9. The right eye was more frequently involved than the left eye (OS: OD = 2: 8, the side was unknown in five patients). The most common tumor type was undifferentiated carcinoma (n = 10) following by squamous cell carcinoma (n = 3), adenocarcinoma (n = 2), mast cell tumor (n = 1) and malignant fibrous histiocytoma (n = 1). PIFM’s were present in 5/9 dogs and 2/15 cats; retinal detachment in 9/11 dogs and 7/14 cats; and glaucoma in 10/16 dogs and 8/15 cats. Conclusion: The most common tumor type with nonlymphomatoid intraocular metastasis was undifferentiated carcinoma in both dogs and cats. The most common metastatic sites were the iris and the ciliary body in both species. Intraocular changes associated with the metastatic lesions included intraocular hemorrhage, glaucoma, and retinal detachment.
Abstract no.: 043
Immunohistochemical and histochemical characterization of 30 primary feline ocular neoplasms
B. H. Grahn,* R. L. Peiffer,† C. L. Cullen* and D. M. Haines*
*Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada, †College of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA
Purpose: The purpose of this study was to determine if a selection of histochemical and immunohistochemical stains, applicable to formalin-fixed paraffin embedded tissues, would prove useful in distinguishing among tumors arising in the eyes of cats. Methods: Tissue sections from 30 intraocular tumors were stained with hematoxylin and eosin and examined by light microscopy. This examination was used as the basis to categorize the tumors into the following groups: 23 intraocular sarcomas, five lightly pigmented diffuse iris melanomas and Two ciliary body adenomas. Serial sections of the neoplasms were immunohistochemically stained with antibodies detecting vimentin, cytokeratins, actin, S100 protein, tyrosinase and the melanoma marker HMSA5, and with periodic acid Schiff (PAS) histochemical stain. Results: All intraocular sarcomas were PAS positive and stained with antibodies to vimentin, additionally five tumors stained for actin, three for tyrosinase, two for S100 and one with antibodies to HMSA5. The two ciliary adenomas were also PAS positive but immunohistochemically stained only for vimentin proteins. The five diffuse iris melanomas were PAS negative and stained with antibodies to tyrosinase, HMSA5 and vimentin, two of the tumors also stained with antibodies to S100. Conclusions: A combination of light microscopy with histochemical and immunohistochemical stains may prove useful in distinguishing among some of the primary intraocular tumors of the cat. Financial disclosure: This study was supported by a Grant from the WCVM Companion Animal Health Fund.
Abstract no. 44
Feline primary ocular lymphosarcoma: immunophenotyping of leukocytes, FeLV status and relationship to idiopathic lymphoplasmacytic uveitis
R. Dubielzig,* H. Steinberg,* B. Fischer,* M. Jackson† and P. Moore†
*College of Veterinary Medicine, University of Wisconsin, Madison, WI, USA, †WCVM, University of Saskatchewan, USA, ‡College of Veterinary Medicine,UC Davis, Davis, CA, USA
Purpose: This study was conducted to examine the natural history of primary feline ocular lymphosarcoma. Methods: Sixty-one cases were retrieved from submissions between 1987 and 1999. Age, sex, laterality and tumor extension, serologic history, and survival was determined. Fifty-seven tumors were examined for tumor cell phenotype, FeLV antigen and genome. The lymphocyte phenotype markers used were: 1. TCR/CD3 for T cells, 2. BCR/CD79 for B cells, 3. CD11/CD18 for phagocytes, and 4. CD45A for common leukocyte antigen. The gp70 antibody was used to identify FeLV antigen in tissues. For FeLV PCR, DNA was extracted from 20 nm paraffin sections and a 166 base pair region of the FeLV long-terminal repeat was amplified. Results: Males outnumbered females (38/20); mean age was 10.8 years and no breed predilection existed. Twenty-five cats had lymphosarcoma alone; 36 had concurrent uveitis (10 trauma associated). Occurrence was slightly greater OD (28/23). Nineteen per cent were FeLV (+) and 33%, FIV (+). Cats having lymphosarcoma with uveitis expressed CD11/CD18, TCR/CD3, BCR/CD79 or no markers in 73%, 41%, 18% & 14%, respectively. Evidence of FeLV occurred in 36% of these cases. Tumor distribution was nodular anterior uveal in 57%. Cats with only lymphosarcoma, 72% were diffuse anterior uveal in distribution and tumor antigen expression was 56% BCR/CD79, 40% CD11/CD18, 32% none, and 20% TCR/CD3. FeLV was present in only 16%. In tumors from 10 cats with traumatic uveitis: 20% exhibited FeLV infection, 60% exhibited no antigen expression, 20% BCR/CD79, and 20%, CD11/CD18 expression. Eighty per cent of tumors were not anterior uveal. Thirteen cats with lymphosarcoma and uveitis that have died had an average survival of 145 days and two cats survived an average of 749 days. Seven cats with pure lymphosarcoma that have died survive a mean of 66 days; five are still alive an average of 570 days. Conclusions: FeLV is infrequently a factor in development of neoplasia. There are differences in tumor distribution, cellular phenotype, and survival between cats with lymphosarcoma with or without concurrent uveitis. Financial disclosure: Supported in part by the Companion Animal Fund. Commercial interest: None.
Abstract no.: 045
The causes of glaucoma in dogs: a morphological survey using a collection of 3980 canine ocular submissions
G. Klauss,* D. Moore,† M. Pipkorn,* H. Swanson,* F. Montiani-Ferreira,‡ N. Tuntivanich,‡ R. Dubielzig*
*SVM, University of Wisconsin, Madison, WI, USA, †RVC, London, England, ‡SVM, Michigan State University, East Lansing, MI, USA
Purpose: To generate a comprehensive list of the causes of canine glaucoma using a large database and to survey the data for risk factors and relationships. Methods: The records from 3980 canine ophthalmic pathology case submissions were surveyed and 1493 cases had glaucoma as a diagnosis either as a clinical finding or as a pathological finding. The age, breed, sex, and morphologic features from each case were analyzed. Results: Glaucoma was a diagnosis in 37.6% (1493/3980) of all canine ophthalmic submissions to the pathology laboratory from 1972 to 2000. 15.6% of glaucoma cases (n = 233) were related to goniodysgenesis. 37.7% of these were in Cocker Spaniels and 8.5% were in Basset Hounds. Other breeds over represented were Samoyeds, Labradors, and Chow Chows. 19.4% of glaucoma cases (n = 290) had intraocular neoplasia. 39.3% of these (n = 115) were melanocytomas, 21.7% (n = 63) were iridociliary epithelial tumors, 17.6% (n = 51) were malignant melanomas, and the remainder were lymphoma, metastatic tumors, and other tumors. An additional 52 cases (3.5%) had melanosis distinct from melanocytoma. 26.5% (n = 395) had preiridal fibrovascular membranes (PIFM) and this was considered to be the primary cause of glaucoma in 271 cases. 58.5% (231/395) had concurrent retinal detachment. Although 31.4% (n = 469) had uveitis as part of the disease complex, 11.5% (n = 172) had uveitis as the primary cause of glaucoma, and in 60 of these uveitis was diagnosed as lens induced because of concurrent cataract. 5.2% (n = 77) were globes which developed glaucoma after intraocular surgical procedures; 37 (48.1%) of these cases were after phacoemulsification. 3.1% (n = 46) had glaucoma associated with iridociliary cysts and all but four were in Golden Retrievers. 28.3% (13/46) of all dogs less than one year of age with glaucoma also had collapse of the anterior chamber with multiple defects in Descemet’s membrane. 6.6% (n = 99) had lens luxation and terrier breeds were over represented. 15.3% (n = 228) had an unknown or undetermined cause of glaucoma and 59.6% (n = 136) of these were evisceration specimens. Conclusions: Glaucoma is a common reason for enucleation or evisceration in dogs and many different lesions are associated with glaucoma in dogs. Goniodysgenesis, neoplasia, PIFM, uveitis, and lens luxation are the major lesions associated with glaucoma development. Financial disclosure: Supported by Comparative Ocular Pathology Laboratory of Wisconsin. Commercial interest: None.
Abstract no.: 046
Follicle-associated epithelium of canine conjunctiva-associated lymphoid tissue (CALT): morphologic characterization and functional significance
E. A. Giuliano,* C. P. Moore* and T. E. Phillips†
*College of Veterinary Medicine, Ophthalmology Service, University of Missouri-Columbia, †Division of Biological Sciences, University of Missouri-Columbia, MO, USA
Purpose: Current concepts in mucosal immune protection include the continuous uptake of foreign material by specialized epithelial cells known as membranous (M) cells and their subsequent delivery of antigenic particles to the organized lymphoid tissue located just beneath their basolateral membranes. The purpose of this study was to characterize the follicle-associated epithelium (FAE) overlying the conjunctival lymphoid nodules obtained from the nictitans of healthy dogs and to determine if the lymphoepithelium of CALT in this species contains M cells analogous to those described in other regions of mucosa-associated lymphoid tissue (MALT). Methods: The lymphoid follicles from the bulbar surface of the nictitating membranes from four healthy dogs (eight eyes total), euthanized for purposes not related to this study, were examined. Nictitating membranes were harvested immediately postmortem and a minimum of 12 lymphoid nodules from each third eyelid were isolated and dissected using a Zeiss operating microscope. At least three lymphoid follicles from each eye were examined by light microscopy, transmission electron microscopy, and scanning electron microscopy using standard fixation and embedding protocols. Results: The FAE overlying lymphoid nodules from each eye demonstrated morphological features similar to those described for M cells including: attenuated apical cell surface with small microvilli and microfolds, invaginated basolateral membrane that forms a cytoplasmic pocket containing predominantly lymphocytes and some macrophages, and diminished distance between the apical and pocket membrane to enable more efficient transcytosis. Conclusions: Analysis of the FAE overlying the lymphoid nodules present along the bulbar surface of the nictitating membranes in normal dogs indicates that specialized surface epithelial cells, analogous to M cells, exist. Documentation of this cell type is of clinical relevance in the study of primary ocular disease, including infectious, allergic, and autoimmune pathobiological processes, as well as a potential means of vaccination and drug delivery. These data will serve as a framework for future investigation of conjunctival mucosal immunity in this and other animal models. Studies designed to investigate if putative M-cells found in canine CALT demonstrate selective binding and preferential uptake of tracers conjugated to physiological ligands compared to the surrounding epithelium are currently underway. Financial disclosure: Supported by a Committee on Research grant from the Department of Veterinary Medicine and Surgery, University of Missouri-Columbia. Commercial interest: None.
Abstract no. 47
A report of lyme disease (Borrelia burgdorferi) with primary ocular involvement in a dog
A. K. Weigt, R. B. Duncan Jr. and J. P. Pickett
VA-MD Regional College of Veterinary Medicine, Blacksburg, VI, USA
Purpose: To report a case of Lyme disease with primary ocular lesions in a dog. Methods: A 4-year-old female Rottweiler presented to the VTH with acute secondary glaucoma and blindness after a two month history of hyphema and uveitis. The rDVM had performed a CBC, serum biochemistry panel, ACT, PTT and PTT, and vonWillebrand’s factor, all of which were within normal limits. The rDVM treated the dog with systemic, immunosuppressive, doses of corticosteroids and the dog had since become lethargic and anorexic. Results: Physical examination at the VTH revealed absolute glaucoma in the right eye, diffuse muscle wasting and an equivocal splenomegaly. Further diagnostics were performed and abnormalities included thrombocytopenia, mature leukocytosis, reactive lymph node hyperplasia, and a polyclonal gammopathy. Thoracic radiographs were within normal limits, and the dog tested negative for ehrlichiosis, Rocky Mountain Spotted Fever, brucellosis, and antinuclear antibody. Serum antibody values for Borrelia were 1: 64 IgM and 1: 4096 IgG. This result was confirmed with Western Blot analysis used to distinguish Borrelia titers from vaccine-induced titers and other spirochete infections. PCR was performed on the enucleated eye and two Lyme-specific genetic markers were positive, including outer surface protein A (ospA) gene and 23S rRNA gene. Conclusions: To our knowledge, this is the first case of PCR being used as a diagnostic tool for Lyme disease with primary ocular involvement. Previous studies of Lyme disease in dogs, reports an incidence of ocular lesions as the primary observation in 5/110 dogs (JAVMA 1990; 197 (7) 893–898). Lyme disease should be considered in endemic areas as a possible etiology for cases of hyphema and uveitis. Commercial interest: None.
Abstract no.: 048
Ocular characteristics and normal conjunctival flora in the american opossum (Didelphis virginiana) and raccoon (Procyon lotor)
C. L. Pinard,* A. H. Brightman,* T. D. Everson,* T. J. Yeary,† L. K. Cox,† M. M. Chengappa† and H. J. Davidson*
*Department of Ophthalmology, Kansas State University, †Department of Pathology and Diagnostic Medicine, Kansas State University, Manhattan, KS, USA
Purpose: To establish ocular characteristics and reveal normal conjunctival bacterial flora of the opossum (Didelphis virginiana) and raccoon (Procyon lotor). Methods: Ophthalmic examinations were performed on 17 sedated opossums and 10 raccoons trapped in Manhattan, Kansas. The anterior structures of the eyes were examined with a direct ophthalmoscope and measurements of adnexal structures were carried out with a Jameson caliper. Three culture specimens were obtained from the inferior conjunctival sac. The first swab was submitted for aerobic bacterial identification, the second for culture and PCR (Polymerase Chain Reaction) for Mycoplasma and the third for Chlamydia PCR. Results: Both the raccoon and the opossum had normal appearing holangiotic mammalian eyes and no ocular abnormalities were noted among the animals. All conjunctival specimens cultured positive for one or more species of aerobic bacteria. For the opossum samples, the most common isolate found was Staphylococcus spp. (82%). Other isolates included Streptococcus spp. (29%), Bacillus spp. (29%), Corynebacterium spp. (12%) and Enterococcus faecalis (6%). The majority (65%) of the opossums had more than one bacterium present in their conjunctival microflora. PCR analysis of opossum samples revealed positive results for Mycoplasma (12%) and Chlamydia (18%). Cultures submitted from opossum and raccoon conjunctivas for Mycoplasma were not positive for growth. The most common isolate in raccoon conjunctiva was Bacillus spp. (66%). Other isolates included Streptococcus spp. (33%) and Staphylococcus spp. (33%), Escherichia coli nonhemolytic (22%), Enterococcus faecalis (22%). Eighty per cent of the samples submitted from the raccoons had more than one organism recovered. PCR analysis of raccoon samples revealed 33% recovery of both Mycoplasma and Chlamydia. Conclusions: Common species of bacteria were found in normal appearing opossum and raccoon eyes. Mycoplasma and Chlamydia can be part of the normal conjunctival flora of opossums and raccoons. Supported by the Diagnostic Laboratory of the College of Veterinary Medicine, Kansas State University. Commercial interest: None.
Abstract no. 49
Aqueous humor analysis in llamas and alpacas
M. L. Aubin, J. R. Gionfriddo, K. R. Mama and C. P. Powell
College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO, USA
Purpose: To evaluate the composition of aqueous humor from normal llamas (Lama glama) and alpacas (Lama pacos) .Methods: Aqueous humor samples were obtained via anterior chamber paracentesis from 10 llamas and 10 alpacas that were under heavy sedation. Chemical analysis included measurements of sodium, potassium, magnesium, chloride, bicarbonate, phosphorous, glucose, osmolality and pH. Comparison between llamas and alpacas was carried out using the Wilcoxan two-sample test. Results: With the exception of potassium, no significant difference between llama and alpaca aqueous humor composition was found. Mean ± standard deviation values for llamas and alpacas, respectively, were: sodium (154.7 ± 2.1, 152.7 ± 2.1 mEq/L), potassium (5.3 ± 0.4, 4.6 ± 0.4 mEq/L), magnesium (1.8 ± 0.1, 1.7 ± 0.1 mg/dL), chloride (130.0 ± 1.6, 127.0 ± 3.3 mEq/L), bicarbonate (19.2 ± 1.5, 20.2 ± 2.3 mEq/L), phosphorous (2.7 ± 0.3, 2.5 ± 0.4 mg/dL), glucose (80.3 ± 3.9, 80.8 ± 7.3 mg/dL), total protein (29.0 ± 8.6, 31.5 ± 10.1 mg/dL), and osmolality (305.8 ± 11.8, 306.2 ± 4.9 mOsm). pH was in the 7.5–8.0 range for both species. Potassium levels were higher in llamas than alpacas (P = 0.003). Conclusions: No significant difference between llama and alpaca aqueous humor was noted for all parameters except potassium. Potassium levels were higher in llamas than alpacas. The aqueous humor content of llamas and alpacas is similar to that of other species that have been examined. Financial disclosure: Supported by the College Research Council of the College of Veterinary Medicine and Biomedical Sciences, Colorado State University. Commercial interest: None.
Abstract no.: 050
Laser flaremetry evaluation of experimental blood–aqueous barrier disruption in cats
A. J. Rankin, S. G. Krohne and J. Stiles
School of Veterinary Medicine, Purdue University, West Lafayette, IN, USA
Purpose: The purpose of this study was to establish a feline model of experimental blood–aqueous barrier disruption. Methods: The FC-1000 Kowa laser flare-cell meter was used to measure the aqueous flare at 4, 8, and 26 h after disruption of the blood–aqueous barrier in two experimental models. In both models the left eye was the untreated control. Paracentesis model: Complete paracentesis of the anterior chamber was performed in the right eye of 11 cats (8 neutered males, 3 females) under sedation. Pilocarpine model: Topical 2% pilocarpine was applied to the right eye at 8 am, 2 pm, and 6 pm in nine cats (six neutered males, and three females). Intraocular pressure, pupil diameter, and aqueous flare were recorded at each time point OU. Results: The 95% confidence intervals for the average flare values (photon counts per millisecond) for the paracentesis model are at time 0: OD (8.1±0.74), OS (9.0±2.2); 4 h: OD (134.2±25.6), OS (9.15±3.6): 8 h: OD (78.1±21.9), OS (12.2±6.8); 26 h OD (27.9±5.7), OS (8.8±1.7). The 95% confidence intervals for the average flare values for the pilocarpine model are at time 0: OD (5.8±2.0), OS (7.3±1.5); 4 h: OD (13.2±5.3) OS (7.5±1.2); 8 h: OD (24.4±6.8), OS (7.8±2.8); 26 h: OD (10.0±2.2), OS (8.4±2.7). Conclusions: The paracentesis model induced a greater breakdown of the blood–aqueous barrier than the pilocarpine model in cats. Financial disclosure: Supported by ASVO. Commercial interest: None.
Abstract no.: 051
Clinical experience with n-butyl cyanoacrylate adhesive in the management of canine and feline corneal disease
C. M. Watté, G. J. McLellan,* R. Elks, K. Hartley and D. L. Moore
Royal Veterinary College, University of London, UK, *Veterinary Medical Teaching Hospital, University of California, Davis, USA
Purpose: To examine and evaluate clinical indications and postoperative outcome in a series of small animal patients in which corneal disease was managed by the application of n-butyl cyanoacrylate adhesive. Methods: In this retrospective study, all small animal patients presented to the Queen Mother Hospital for Animals, Royal Veterinary College, between April 1998 and April 2000, in which corneal disease was managed by the application of n-butyl cyanoacrylate were identified. Case records were reviewed and indications for application, concurrent complicating factors, glue retention time, and extent of subsequent corneal reaction and scarring were noted for each case. Where indicated, information regarding postoperative comfort, and long-term follow-up data concerning visual and cosmetic outcome were obtained from owners and referring veterinarians using telephone questionnaires. Results: Thirty-eight patients (29 dogs and 9 cats) were identified. The mean ages of dogs and cats included in the study were 6.9 ± 4.39 and 6.6 ± 4.77 years, respectively. Cyanoacrylate adhesive was applied bilaterally in one dog and one cat and unilaterally in all other cases. Left and right eyes were equally affected and no gender predisposition was evident. Although no individual breeds were over-represented relative to the hospital population, 45% of dogs and 55% of cats were considered to represent exophthalmic/lagophthalmic breeds. Indications for corneal gluing included stromal ulceration (26/40 eyes); descemetocoele (4/40 eyes); corneal laceration/foreign body (5/40 eyes); lamellar keratectomy (3/40 eyes) and superficial ulceration (2/40 eyes). Concurrent complicating factors were identified in 67.5% of eyes and included keratomalacia (10/40 eyes); confirmed bacterial keratitis (4/40 eyes); corneal edema related to endothelial disease (3/40 eyes) and keratoconjunctivitis sicca (3/40 eyes). Cyanoacrylate was generally well tolerated by patients, with only 8/34 eyes demonstrating blepharospasm and increased lacrimation postoperatively. In the 35 eyes for which adequate follow-up information was available, retention time of cyanoacrylate varied widely, from < 1 week to approximately 6 months, but was < 2 months in the majority (89%) of eyes. The presence of concurrent complicating factors did not appear to influence glue retention time or clinical outcome. Exaggerated corneal vascularization was an infrequent complication, noted in six canine eyes, and did not appear to be related to initial corneal disease, glue retention time or breed. Conclusion: N-butyl cyanoacrylate offers a convenient, economical and effective alternative to other treatment modalities, such as conjunctival grafts, in the management of corneal defects in canine and feline patients. Commercial interest: None.
Abstract no.: 052
The effect of chronic corneal epithelial debridement on epithelial and stromal morphology and extracellular matrix components of the dog
E. Bentley, S. F. Campbell, H. M. Woo and C. J. Murphy
School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI, USA
Purpose: This study was undertaken to determine the effect of creating a chronic corneal epithelial defect on epithelial and stromal morphology and extracellular matrix components in the dog, and to compare these findings to those seen in spontaneous canine chronic corneal epithelial defects. Methods: Five normal young adult laboratory Beagles were used. Complete ophthalmic examinations and Schirmer tear tests were normal for all dogs. Six-mm diameter axial epithelial wounds were created in one eye by mechanical debridement once weekly for 8 weeks. Slit lamp biomicroscopy and corneal pachymetry were performed weekly prior to wounding. Three days following the last debridement, dogs were humanely euthanized, and corneas were fixed for light microscopy and transmission electron microscopy (TEM). Immunolocalization of laminin, collagen VII, collagen IV, and fibronectin was performed. All animals were treated in accordance with the ARVO Statement for the Use of Animals in Ophthalmic and Vision Research. Results: Corneal thickness was not significantly different from the contralateral control eyes at any point. All samples showed epithelial dysmaturation and 4/5 samples had formation of a small rim of nonadherent epithelium adjacent to the bared stroma. All samples had a mild suppurative anterior stromal infiltrate and generalized fibroplasia. All samples had an anterior stromal acellular zone with otherwise no change in stromal morphology. This acellular zone was present in the area of denuded stroma as well as under adjacent attached epithelium, and had a mean thickness of 79 μm (SD±23). Laminin, collagen IV, and fibronectin were present on the surface of the denuded stroma in all 5 samples, and collagen VII was present on the surface in 4/5 samples. TEM demonstrated the presence of a complete basement membrane on the surface of the stroma and normal appearing stromal fibrils in the acellular zone. Conclusions: Epithelial dysmaturation and nonadherent epithelium are found secondary to chronic epithelial defects. This is similar to findings in dogs with spontaneous chronic corneal epithelial defects (SCCED). Differing from most dogs with SCCED, the basement membrane remains intact on the surface of the erosion in this model. The acellular zone in this model is distinct from that found in dogs with SCCED. These findings suggest that the underlying changes in stromal morphology in SCCED are not attributable to changes secondary to the presence of a chronic epithelial defect. Financial disclosure: Supported by NEI grants EY10841-01 and EY12253-01. Commercial interest: None.
Abstract no.: 053
TGFβ–2 levels in tears of normal dogs and dogs with refractory corneal ulcers
I. Jurk, B. Gilger, E. Malok, V. Valentine, M. Davidson and J. Allen
Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina, USA
Purpose: Refractory or indolent corneal ulcers are commonly seen in dogs and suspected to be an ocular condition of mixed etiologies that require different treatment strategies. In the Boxer, an epithelial adhesion defect has been identified whereas in the non-Boxer breed the pathogenesis of indolent ulcers is not known. Healing of corneal ulcers is dependent on endogenously produced peptide growth factors, e.g. transforming growth factor beta (TGFβ). TGFβ is a multifunctional cytokine, which has been identified in human and animal tears, and plays an important regulatory role in later stages of corneal wound healing. The purpose of this study is to investigate whether indolent ulcers in non-Boxer breeds of dogs are associated with decreased concentration of TGFβ in tears. Methods: Tear fluid was collected atraumatically from the lower conjunctival fornix fluid of 5 non-Boxer breeds of dogs with indolent corneal ulcers, without topical anesthesia and before evaluation of the Schirmer tear test (> 15 mm/min). The diagnosis of indolent ulcers was made based on the characteristic appearance of the lesion and a history of recurrence/failure to conventional treatment. Tear samples were acid-activated, transferred to sterile Eppendorf tubes, and stored at–80 °C until analysis for total TGFβ-2 using a commercially available specific-capture ELISA kit (R & D Systems), per manufacturer’s directions. Tear samples of 13 age-and sex-matched control dogs were also collected and analyzed. Results: Tears of non-Boxer breed dogs with indolent ulcers contained significantly (P < 0.009) lower concentrations of TGFβ-2 (mean 376 pg/mL) compared to the control dogs (mean 4119 pg/mL). Conclusions: Decreased concentrations of TGFβ-2 in tears of eyes with indolent ulcers suggest that TGFβ-2 may be important in proper healing of corneal ulcers. Topical TGFβ-2 should be investigated as therapy for nonhealing corneal ulcers. Financial disclosure: Supported by funds from the State of North Carolina, the American College of Veterinary Ophthalmologists, and the American Society of Veterinary Ophthalmology.
Abstract no.: 054
Survival of equine herpesvirus-4, feline herpesvirus-1, and feline calicivirus in multidose ophthalmic solutions
E. S. Storey, P. A. Gerding, G. Scherba and D. J. Schaeffer
College of Veterinary Medicine, University of Illinois, Urbana, IL, USA
Purpose: To determine survival over time of infectious equine herpesvirus-4 (EHV-4), feline herpesvirus-1 (FHV-1), and feline calicivirus (FCV) in three commercially available and commonly used ophthalmic solutions (eyewash, fluorescein, and proparacaine) using plaque and TCID50 assays. Methods: Three separate trials were performed using EHV-4, FHV-1, and FCV originally isolated from the eyes of animals referred to the University of Illinois. EHV-4 was propagated in MDBK cells and FHV-1 and FCV in CRFK cells. Survival of each virus was evaluated in eyewash, sodium fluorescein, or proparacaine HCl. Cell culture media served as a control solution. For each trial, a 5-mL aliquot of each ophthalmic solution was inoculated with a presumptive infectious dose of either 106, 105, or 104 plaque forming units (pfu) of virus per ml. For each virus 2 separate 5 mL aliquots of cell culture media were inoculated with 106 pfu of virus per ml and maintained at temperatures specified within the manufacturer’s recommendations: eyewash and fluorescein at 25 °C and proparacaine at 4 °C as temperature controls. Titer of infectious virus was determined from the 0.5 mL aliquots obtained at 1, 8, 24, and 3, 5, and 7 days post inoculation. Analysis of variance and/or covariance was performed to determine if, for a given drug, there were any differences in time/titer curves among viruses over all inoculation titers and/or any differences between viruses on the time/titer curves for specific inoculation titers. Results: EHV-4, FHV-1, and FCV were present in eyewash for 7 days, 5 days, and 7 days, respectively. Eyewash did not decrease survival time of any virus when compared to controls. EHV-4 and FHV-1, both enveloped viruses, were not recovered at any time 1 h post inoculation in fluorescein. FCV, a nonenveloped virus, was present in fluorescein for 7 days. EHV-4 and FHV were not present in proparacaine at any time 1 h post inoculation, but FCV was recovered at up to 24 h post inoculation. Conclusions: EHV-4, FHV-1, and FCV may all be readily transmissible via the eyewash solution used in this study. Risk of iatrogenic transmission of the three viruses used in this study was significantly reduced in both fluorescein and proparacaine solutions. FCV, the only nonenveloped virus evaluated, remained viable longer in both fluorescein and proparacaine solutions. Financial disclosure: Supported by Companion Animal Grant 1–6-48576, University of Illinois. Commercial interest: None.
Abstract no.: 055
Effect of amlodipine on ocular blood flow in beagles with POAG
T. J. Cutler, D. E. Brooks, M. E. Kallberg, A. M. Komaromy, T. Miyabayashi and K. N. Gelatt
Departments of Small and Large Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, Florida 32610, USA
Purpose: To evaluate the effects of the l-type calcium channel blocker amlodipine on ocular blood flow (velocity and resistance) in Beagle dogs with POAG. Methods: Six dogs were examined under isoflurane anesthesia before and 7 days after receiving 0.125 mg/kg amlodipine orally once daily. Eyes were examined in alternating order. Color Doppler imaging (CDI, Aloka SSD-1700, 7.5 MHz convex array transducer) was performed on each eye under 100% O2 inhalation, then under carbogen (5% CO2: 95% O2). Triplicate measures of blood flow through the distal short (SPCA) and long (LPCA) posterior ciliary arteries and the ophthalmic artery (OA) were performed for each eye. Resistive index (RI), peak systolic velocity (MAX), and end diastolic velocity (MIN) were calculated for each artery. Confocal scanning laser flowmetry (HRF, Heidelberg Industries GmbH) of each optic nerve head (ONH) was also performed for each gas. Blood flow velocity (VEL), flow (FLW) and volume (VOL) in a 50-pixel box were calculated by the HRF for the ONH and nasal and temporal retina. Mean arterial pressure (MAP), end expiratory CO2, and pulse rate were monitored and evaluated as cofactors. Statistical analysis: was performed using a general mixed effects linear mode. All variables except RI were logarithmically transformed prior to analysis. Significance was ascribed to P-values < 0.05. Results: Beagles with POAG had no significant effects or differences in RI under either gas. MAP varied inversely with both RI and PI for SPCA and LPCA (each P < 0.006). There was a significant increase in SPCA and OA MAX when the gas was changed from O 2 to carbogen, but amlodipine treatment did not alter this effect (P > 0.05). Amlodipine mildly increased (13.3%–15.2%) the OA MIN under each gas condition, but P > 0.05. In contrast, amlodipine-treated normal Beagles examined previously had a ∼10% decrease in RI in each artery, an increase of 20.8% (LPCA) and 42.1% (OA) in MIN (P < 0.01) and a 6.6% increase (OA) in MAX (P < 0.02). HRF analysis showed a general reduction (treatment effect) in VEL, FLW and VOL. under each gas for the ONH but not the surrounding retina (0.03 < P < 0.05). Conclusions: Beagles with POAG do not have increased ocular blood flow velocity after amlodipine administration, in contrast to ophthalmically normal laboratory Beagles. Simulated metabolic stress (carbogen inhalation) had mild effects on blood flow, but amlodipine did not alter or enhance this effect. Beagles with POAG may have no further ability to autoregulate blood flow, or autoregulation may be dysfunctional. Calcium channel blockers may still be neuroprotective by reducing glutamate accumulation. Changes in systemic MAP and pulse rate can significantly affect the measurement of CDI parameters. Financial disclosure: Supported by the College’s Resident Competitive Grant Competition. Commercial interest: None.
Abstract no.: 056
Alginate as a new biomaterial for the growth of porcine retinal pigment epithelium
D. R. Brown, T. E. Eurell, P. A. Gerding and R. E. Hamor
College of Veterinary Medicine, Department of Veterinary Clinical Medicine, University of Illinois, 1008 West Hazelwood Drive, Urbana, Illinois 61802, USA
Purpose: Alginate culture is an all-aqueous cell culture system that is safe and easy to use within biological systems. A major benefit of this system is ease of recovery of cultured cells from within the matrix. Alginate has been previously used as a culture medium to maintain and propagate chondrocytes and hepatocytes. The purpose of this study was to determine if porcine retinal pigment epithelium (RPE) could be cultured in alginate beads. Porcine RPE was chosen as it is routinely used as an animal model for the study of diseases of the RPE. Criteria used to evaluate culture growth included an increase in cell numbers and maintenance of both melanin pigmentation and normal morphologic appearance of the retinal pigmented epithelium. Methods: RPE was harvested from enucleated porcine eyecups by enzymatic digestion with 0.25% trypsin. Single RPE cells were then obtained using differential sedimentation. RPE cells were added to alginate in both high (5×105 cells/mL) and low (1×104 cells/mL) concentration to evaluate effect of seeding density on RPE growth. Alginate beads were created by dropping the suspension into 102-mM CaCl2. Alginate beads were then placed in a 96-well plate and maintained in culture for 14 days. RPE cell numbers were counted at the beginning of the study (T0) and at day 14(T14). RPE cells were released from within the alginate beads by sequestration of the gelling ion with sodium citrate. RPE cells were then counted and cell viability checked by staining with trypan blue. RPE numbers at day 0(T0) and at day 14(T14) were compared using the student t -test. Results: Mean RPE numbers were significantly higher (P(0.001) at day 14 when compared to day 0 for both the low concentration–Plate 1 and high concentration-Plate 2. There appeared to be minimal loss of pigment within the RPE cells cultured in alginate and morphology remained unchanged between T0 and T14. Plated RPE showed loss of intracellular pigment and changes in morphology. Conclusion: Results of this study indicate that porcine RPE can be maintained in alginate culture and will increase cell numbers while maintaining normal morphology and pigmentation. Commercial interest: None.
Abstract no.: 057
Video dacryocystorhinoscopy in horses: a novel diagnostic procedure
N. J. Cassotis, D. T. Ramsey, S. M. Petersen-Jones and D. Letavish
College of Veterinary Medicine, Michigan State University, East Lansing, MI, USA
Purpose: Evaluation of video nasolacrimal endoscopy (dacryocystorhinoscopy) for diagnosis of nasolacrimal disorders of horses. Methods: Ten horses determined to be free of nasolacrimal disease based on history and physical examination were selected for study. These horses did not have a history of chronic epiphora, ocular discharge, or dacryohemorrhea. Additionally, these horses did not have a history of nasolacrimal cannulation, flushing or probing. Two horses determined to have secondary acquired nasolacrimal duct obstruction (SANDO) were subsequently evaluated. Dacryocystitis was diagnosed based on history of acute or chronic epiphora, mucopurulent discharge from at least one nasolacrimal punctum on the affected side, or waxing and waning of signs with use or discontinuance of topical anti-inflammatory or antibiotic medications. A flexible, 1.1-mm (external diameter), 50-cm (length) single fiber optic endoscope was utilized under general anesthesia. An external camera, light source, and video recording unit captured images. Results: (A video review of relevant structures and the clinical cases will be given during the presentation). The dacryoscope was introduced through the lower or nasal ostium of the nasolacrimal duct (NLD). Continuous flushing of the duct during the procedure through either puncta maintained distention of the membranous duct. The endoscope allowed steering, thereby permitting structures within the dilated, distal, membranous regions of the NLD to be examined. Examination of normal subjects was uninhibited with this diameter endoscope. Easy delivery from distal nasal ostium to eyelid puncta was possible in all normal subjects. Additionally, clear visualization of the nasolacrimal duct lining was obtained in all normal horses. The two clinical cases involved an intraluminal stricture of the proximal duct, and an extraluminal compression of the distal duct. The luminal stricture occurred at the transition between osseous and membranous canals. This is additionally the narrowest section of the duct. The extraluminal compression of the distal membranous duct occurred at the level of the inferior concha’s basal cartilage. Comparison with the unaffected side showed marked loss of volume of this widely dilated region of the duct. Localization of the obstructions was confirmed in both cases by contrast dacryocystorhinography during the same anesthetic period. Conclusions: This is a novel and potentially valuable diagnostic test. Video dacryocystorhinography will additionally allow the introduction of new therapeutic strategies for SANDO or other obstructive nasolacrimal disorders in horses.