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Keywords:

  • intraocular release of lens protein;
  • lens capsule disruption;
  • perforating traumatic corneal laceration;
  • phacoclastic uveitis;
  • prophylactic lens removal;
  • secondary glaucoma

Abstract

  1. Top of page
  2. Abstract
  3. Introduction
  4. Material and Methods
  5. Results
  6. Discussion
  7. Conclusion
  8. References

Objective  Examine prognostic factors that may indicate when surgical lens removal is indicated to prevent vision-threatening complications in patients presented following traumatic perforating corneal laceration with associated lens capsule disruption.

Procedures  Seventy-seven patients (10 cats and 67 dogs) were evaluated with this injury; of these, 47 were presented acutely and treated surgically and/or medically. Successful outcome was defined as functional vision in the treated eye.

Results  The 47 patients with acute injuries were divided into 3 treatment groups A-C for comparison; A - corneal repair/lens removal (n = 15), B - corneal repair/no lens removal (n = 9), C – medical management (n = 23). Groups A and B showed a significantly greater rate of vision loss compared to Group C that was most obvious greater than 18 months post-injury (P = 0.029 and 0.0097, respectively). Cox proportional hazards regression analysis found a significantly higher increased rate of vision loss in Group A (HR = 4.5; P = 0.023) and a higher but nonsignificant increased rate of vision loss in Group B (HR = 3.0; P = 0.23) compared to Group C after controlling for age and cause of injury. The length of the corneal laceration and time interval from injury to referral were also relevant prognostic factors.

Conclusions  Medical management is an appropriate therapy for patients of all ages suffering perforating corneal injuries with associated lens capsule disruption. Patients with corneal injuries requiring surgical repair or managed by lens removal following corneal repair suffered vision-threatening complications approximately 3 to 4.5 times the rate of patients treated by medical management, respectively. Favorable prognostic signs for treatment by medical management include good corneal wound apposition and a formed anterior chamber without uveal prolapse or continued aqueous leakage.


Introduction

  1. Top of page
  2. Abstract
  3. Introduction
  4. Material and Methods
  5. Results
  6. Discussion
  7. Conclusion
  8. References

Traumatic corneal laceration with associated lens capsule disruption is a common eye injury in small animal ophthalmology practice. Cat claw trauma is one common cause of this type of injury in adolescent dogs and cats and may occur shortly after introduction into a new household. These animals are often naïve as to the territorial, aggressive nature of adult cats presiding in or around a new household, which place them at great risk for this type of injury. Immediate therapy and possibly surgery to include lens removal have been regarded as essential to prevent vision-threatening complications associated with exposure of the immune system to previously sequestered lens protein. The resulting phacoclastic uveitis is often severe, progressive and associated with inflammation involving intralenticular neutrophils and perilenticular fibroplasia.1 Pupillary occlusion and secondary glaucoma are common complications and often result in the loss of vision.1 Bacterial infection resulting in septic endophthalmitis has also been reported and may occur up to 2 years following injury.2,3 Patients subjected to early lens removal have responded favorably in two retrospective studies of dogs and cats with this type of injury.4,5 Prophylactic lens removal to prevent vision-threatening complications has been advocated with lens capsule tears of 1.5 mm or greater or when substantial disruption of lens cortex is present.4 Large, contemporary case studies to support this recommendation are currently lacking, and acute medical management of patients with this injury is also unreported.

The purposes of this study were to describe the features, management, and prognosis of traumatic perforating corneal laceration with associated lens capsule disruption in canine and feline patients and to assess the success of different treatment options in preserving or restoring vision in these patients. Prognostic factors were evaluated to determine whether lens removal is essential to prevent vision-threatening complications resulting in blindness or enucleation.

Material and Methods

  1. Top of page
  2. Abstract
  3. Introduction
  4. Material and Methods
  5. Results
  6. Discussion
  7. Conclusion
  8. References

Study population and data retrieval

All medical records of the Animal Eye Clinic (Arlington, TX, USA) were reviewed by computer search for those patients with a diagnosis of traumatic corneal laceration with associated lens capsule disruption and/or traumatic cataract for the 11-year period of 1999–2009. Those patients meeting other criteria in this study but deemed to have suffered catastrophic eye injury associated with blunt force trauma, severe globe compression (i.e., dog bite or hit-by-car injuries), or projectile injury were excluded. Specific data abstracted included (i) age, breed, sex, and species of the patient; (ii) which eye was injured and the source of the injury, if known; (iii) length of corneal injury and lens capsule disruption (as measured by calipers or when possible estimated from the average width of canine and feline cornea, 16 and 17 mm, respectively)6; (iv) time interval from injury to referral, if known; and (v) complications resulting in blindness or enucleation. All patients were photographed at each examination to document and quantify any changes. A Nikon SLR (single-lens reflex) camera (models D100 and D300) with a 105-mm macro Nikkor lens was used for all digital photography.

Patient exclusion

Blunt force trauma to the globe, high-speed projectile penetration of the globe, or crushing globe injuries, such as dog bite, often result in lens capsule rupture and corneal and/or scleral laceration. Catastrophic damage to the retina, optic nerve, and/or ciliary body often results in complications and blindness that are unrelated to the subsequent immune reaction caused by the intraocular release of lens protein. As a result, all patients with this type of trauma were excluded except for one dog bite injury that was not accompanied by catastrophic globe injury.

Patient categories and treatment groups

Patients were initially divided into two categories (Table 1). Category 1 was composed of those patients deemed to have potential for vision, and it was further subdivided into three treatment groups as follows: (A) corneal repair with lens removal, (B) corneal repair without lens removal, and (C) medical management. Category 2 was composed of patients deemed to have a poor prognosis for vision at initial examination, patients noted to have previously suffered a perforating corneal injury and lens capsule tear as an incidental finding in an eye with functional vision, or patients lost to follow up after the initial examination or surgery. Recheck examinations were recommended at 1, 2 weeks, 1, 2, 6 months, and 1 year after initial examination regardless of the type of treatment. Patients with complications were examined more frequently.

Table 1.   Category of patient and final result. Patients were divided into two categories. Category 1 was composed of those patients deemed to have potential for vision and further subdivided into three treatment groups. Category 2 was composed of patients deemed to have a poor prognosis for vision at initial examination, patients noted to have previously suffered a perforating corneal injury and lens capsule tear as an incidental finding in an eye with functional vision, or patients lost to follow up after the initial examination or surgery. A patient was considered to have a successful outcome if functional vision was restored, which was defined as follows: (i) normal sized globe (ii) a positive menace reflex and (iii) a clear visual axis that allowed detailed funduscopic evaluation of over 50% of the retina. Failures were those patients that suffered complications resulting in blindness or enucleation
Patient categorySuccessFailureUnknownTotal
Patients with potential for vision
 (A) Corneal repair/lens removal69 15
 (B) Corneal repair only63 9
 (C) Medical management194 23
Poor prognosis/Incidental/Lost
 Poor prognosis at initial examination 20 20
 Incidental finding or old injury5  5
 Did not return for follow-up  55
Total3636577

Most patients in Treatment Group A were examined and treated prior to July 2003. All patients in this group had lens capsule tears 2 mm or greater and had lens fiber disruption affecting at least 20% of the lens and/or had lens protein in the anterior chamber. The genesis of Treatment Groups B and C began in July 2003 and was based on successful trial medical management of a lacerated lens in a 2-month-old Labrador Retriever.

Lens removal was performed by phacoemulsification and/or irrigation/aspiration through a 3-mm limbal incision utilizing the existing lens capsule tear (Protégé, Storz Ophthalmics, St. Louis, MO, USA). Usually this was carried out immediately following the closure of the corneal laceration. Both the limbal incision and corneal laceration were closed with 7-0 or 8-0 polyglactin acid (Vicryl; Ethicon, Somerville, NJ, USA) or 9-0 nylon (Ethilon; Ethicon) suture material. Medical management prior to and following lens removal usually included topically applied broad-spectrum antibiotic q4h (Ofloxacin Ophthalmic Solution 0.3% USP; Ethicon or Tobramycin Ophthalmic Solution 0.3% USP; Falcon Pharmaceuticals, Fort Worth, TX, USA), mydriatric q12h (Atropine Ophthalmic Solution 1% USP; Bausch & Lomb, Inc. Tampa, FL, USA), and nonsteroidal anti-inflammatory ophthalmic solution q12h (Ketorolac Tromethamine Ophthalmic Solution 0.5%; Falcon Pharmaceuticals or Diclofenac Sodium Ophthalmic Solution 0.1%; Falcon Pharmaceuticals). Oral medications included 5–7 days on broad-spectrum oral antibiotic amoxicillin (Amoxi-tabs; Pfizer Animal Health, New York, NY, USA) or enrofloxacin (Baytril; Bayer HealthCare, Shawnee Mission, KS, USA) and 2–4 weeks of oral steroidal (prednisone or prednisolone) or nonsteroidal anti-inflammatory medication (carprofen-Rimadyl; Pfizer Animal Health or tepoxalin-Zubrin, Intervet/Schering Plough, Animal Health, Roseland, NJ, USA).

Statistical analysis

Survival analysis (also known as event-time analysis) was used to compare treatment success among the patients in the three treatment groups of Category 1. A successful treatment outcome was a patient with functional vision restored and having (i) a normal sized globe (relative to the fellow eye), (ii) a positive menace reflex, and (iii) a clear visual axis that allowed detailed funduscopic examination of >50% of the retina. Aphakic patients meeting these criteria were considered successful, even though visual acuity was reduced compared with phakic and pseudophakic patients. Those patients suffering vision-threatening complications that resulted in blindness or enucleation were considered failures. For the purposes of the statistical analysis, loss of vision and/or enucleation were the events of interest. Patients lost to follow up and/or with vision at the last recheck examination were treated as censored observations. Patients were censored at the last available recheck time, but at the latest after 18-month follow-up period. Because only three patients experienced known vision loss after more than 18 months of postsurgical convalescence (and their precise times of vision loss could not be ascertained), Cox proportional hazards regression analysis was performed on all patients in the first 18 months following surgery. Patients with vision at 18 months were treated as censored individuals. All models were adjusted for age (in months) if the injury was caused by a cat scratch, length of corneal laceration (in mm), and time from injury to referral (in days). The probability function of maintaining functional vision following the initiation of treatment was estimated using the Kaplan-Meier method, and the difference in the probability functions of the groups was evaluated using a log-rank test. Failures were defined as patients that lost vision following medical or surgical treatment. The rate of vision loss was compared between groups using a Cox proportional hazards regression model, and proportionality was evaluated using likelihood ratio test on the coefficient for a group by centered log-time interaction. In addition, potentially prognostic variables that changed the hazard ratios for treatment groups by more than 10% or that significantly improved the multivariable model using a likelihood ratio test for forward selection were added. Candidate prognostic variables included age, sex, whether the laceration was caused by a cat’s claw or not, the (continuous) time interval between injury and referral, the (continuous) length of the lens laceration (incompletely recorded), and the length of the corneal laceration. Interactions between the main effects were assessed using likelihood ratio tests. Results are presented as hazard rate ratios (HR) and 95% confidence interval (95% CI). Exact chi-square tests of homogeneity were used to compare the proportion of successes and failures between groups. P-values <0.05 were considered statistically significant. EGRET statistical software (Cytel Software Corporation, Cambridge, MA, USA) was used for statistical analyses.

Results

  1. Top of page
  2. Abstract
  3. Introduction
  4. Material and Methods
  5. Results
  6. Discussion
  7. Conclusion
  8. References

Patient population and source of injury

Seventy-seven patients (10 cats and 67 dogs) were divided into two categories and the end-results are summarized in Table 1. The source of the injury and which eye was injured are shown in Table 2. A cat claw was known or strongly suspected to be causative in 52 of the 77 patients (68%). In cat claw injury patients, right and left eyes were almost equal in number (29 vs. 33, respectively). The average dog’s age was 3.1 years and the median age was 1.3 years (range: 2 months–14.6 years) compared with the average and median age of cats, which were 5.1 and 5.4 years, respectively (range: 2 months–15.8 years). Thirty-five of the 77 patients (45%) were 12 months of age or younger, while 26 of the 77 (34%) were 5 months of age or younger at the time of injury. Two-thirds (45 of 67) of the dogs in this study were small breeds (weighing <20 pounds when full-grown), and 29 of the 67 (42%) patients were considered to be brachycephalic and/or exophthalmic breeds. The most common dog breeds were Chihuahua (6), Shih Tzu (6), Dachshund (5), Pitt Bull (4), Yorkshire Terrier (3), Boston Terrier (3), Lhasa Apso (3), Labrador Retriever (3), Pug (3), Terrier mix (3), Australian Shepherd (2), Toy Fox Terrier (2), and Chow Chow (2). Females were over-represented, as 56 of the 77 patients (73%) in this study were sexually intact or spayed females (P < 0.0001), and among the cat claw injury patients, 44 of the 62 (71%) were females (P = 0.0013).

Table 2.   Source of injury and eye injured
Source of injuryCanineFelineTotal
ODOSODOS
  1. OD, right eye; OS, left eye.

Cat claw19233348
Presumed cat claw671 14
Squirrel claw11  2
Cactus needle   22
Thorn2   2
Glass pane1   1
Rawhide chew toy 1  1
Dog bite1   1
Unknown141 6
Total31365577

Rationale for patient treatment

Thirteen of the 47 patients with a favorable prognosis were examined prior to July 2003, and 12 of the 13 had emergent, prophylactic lens removal based on previously described clinical recommendations for patients with this injury.4 The remaining 34 patients were examined after July 2003 and only three had lens removal surgery. The lens was considered irreversibly damaged in two of these three patients and the third developed a sterile lenticular abscess. Vision was lost in two of the three patients (endophthalmitis in one and retinal detachment/secondary glaucoma in the other) and both were enucleated.

In all patients in Treatment Group A, surgical repair of the corneal laceration was performed immediately prior to lens removal and was performed in all other patients (Treatment Group B) with poor apposition of the wound margins or when accompanied by iris prolapse and/or continued aqueous leakage (Fig. 1). Twenty-three of the 38 (61%) patients in this study examined acutely (during the first 72 h following injury) underwent corneal repair.

image

Figure 1.  3-month-old Dachshund Fe, squirrel claw injury OS; Group B. (a) T(time after injury) = <24 h. Following pharmacologic dilation dyscoria due to anterior synechiation was evident at the temporal margin of the 10 mm corneal laceration and the anterior chamber was shallow. Corneal wound apposition was poor and surgical repair of the cornea was performed. The lens capsule tear was estimated to be 10 mm in length. The lens underwent complete resorption within 1 month of surgery and glaucoma blinded the eye sometime between 3 and 26 months post-injury.

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Photographic documentation of lens healing

Serial photography demonstrated that the traumatic cataract usually progressed initially following injury and then rapidly regressed as the lens capsule was sealed by fibrous metaplasia. This process appeared complete in most patients within 2–4 weeks of injury (Figs 2a–e, 3a–d and 4a–e). Two patients exhibited mild clinical signs of iritis because of lens protein extrusion and fibrin effusion at the site of the lens capsule tear. Both required continued medical therapy for a period of 3–4 months until the capsule defect closed spontaneously by fibrous metaplasia (Fig. 5a–e). Large amounts of lens protein in the anterior chamber did not require lens removal on every occasion (Figs 4a–e and 6a–e). Traumatic cataract progressed minimally or not at all in 10 of the 12 patients treated medically and followed longer than 12 months. Two patients showed mild progression of the traumatic cataract over a 48- and 60-month follow-up period, but both maintained functional vision.

image

Figure 2.  7-year-old Terrier cross Fe(s), cat claw injury OS; Group C. (a) T(time after injury) = 2 h. A 2 mm puncture wound in the superior temporal cornea was sealed with a fibrin clot. Plasmoid aqueous, miosis, and lens capsule laceration were noted. (b) T = 4 h. Following pharmacologic dilation, the lens capsule tear was estimated to be 12 mm in length, extended horizontally across the pupil and the superior and inferior margins were clearly visible (arrows). (c) T = 3 days. The cataract appeared larger and more dense. Anterior and posterior lens cortex was affected by the dense yellow infiltrate in the lens fibers and was consistent with edema and possible lens abscessation. Lens removal was recommended but declined. (d) T = 2 weeks. The margins of the lens capsule tear were no longer visible and appear sealed with scar tissue accompanied by dense pigmentation. (e) T = 38 months. The traumatic cataract and lens capsule pigmentation were quantitatively unchanged.

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image

Figure 3.  2-month-old Pitt Bull cross M, cat claw injury OS; Group C. (a) T(time after injury) = 1 day. A 6 mm corneal laceration was partially obscured and sealed by a dense fibrin clot in superior temporal cornea. A small corneal laceration of the third eyelid was noted. Traumatic cataract was visible, but corneal edema and the fibrin clot obscured the lens capsule tear. Medical management was recommended. (b) T = 2 weeks. The corneal laceration is filled with granulation tissue. The traumatic cataract regressed and was partially obscured by corneal edema. (c) T = 1 month. Traumatic cataract was minimal and affected the superior anterior and equatorial cortex. The lens capsule tear was now visible and estimated to be 8 mm. (d) T = 4 months. The traumatic cataract was unchanged. The superior lens equator was irregular and shrunken (arrows), but axial lens remained clear.

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image

Figure 4.  2-month-old Pitt Bull Fe, cat claw injury OD; Group C. (a) T(time after injury) = 2 days. A 6 mm corneal laceration was sealed with a fibrinous blood clot. The anterior chamber is collapsed with lens material touching the corneal endothelium. The lens capsule tear was estimated to be 10 mm in length. Lens removal was recommended but declined by the owner. (b) T = 1 week. The S-shaped corneal laceration sealed with fibrin and the anterior chamber reformed, but remained shallow in the axial corneal region. (c) T = 3 weeks. Granulation tissue partially filled the corneal defect and a focal traumatic cataract remained. (d) T = 60 months. Mild progression of the traumatic cataract occurred and diffusely affected the anterior and posterior lens cortex. (e) T = 60 months. Side-view showed the anterior lens capsule to be adherent to the corneal endothelium.

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image

Figure 5.  4-month-old Shih Tzu Fe, cat claw injury OD; Group C. (a) T(time after injury) = 2 days. A 2 mm corneal puncture wound (arrows) was located in central cornea surrounded by dense corneal edema. Medical management was recommended. (b) T = 2 weeks. Lens fiber edema resulted in vacuole formation in the anterior, posterior and equatorial lens cortex. The length of the lens capsule tear was estimated to be 8 mm. (c) T = 2 months. Lens protein extrusion developed through the lens capsule tear (arrows) and was covered by fibrin. (d) T = 4 months. Fibrous scar sealed the lens capsule tear and protein extrusion resolved. (e) T = 4 months. Lens capsule defect closed by fibrous metaplasia and strand of scar tissue extended from the lens capsule to corneal endothelium.

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image

Figure 6.  2-month-old Terrier cross Fe, cat claw injury OD; Group C. (a) T(time after injury) = 5 days. A 2 mm corneal puncture wound was present in superior temporal cornea and the lens capsule tear was estimated to be 8 mm in length. Medical management was recommended. (b) T = 5 days. Large aggregate of lens protein extended from the lens capsule defect to the corneal endothelium. (c) T = 12 days. Lens protein extrusion was smaller and covered by fibrin effusion. (d) T = 6 weeks. Lens capsule tear was sealed by fibrous metaplasia. Vacoules were present in temporal anterior lens cortex. (e) T = 36 months. The traumatic cataract was focal and mild wrinkling of the anterior lens capsule was noted adjacent to healed capsule tear.

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Patient categories and treatment groups

The 47 patients in Category 1 were subdivided into three treatment groups for comparison of the success or failure of prescribed surgical and/or medical treatment protocols. Group A consisted of 15 patients treated by corneal repair and lens removal. Group B contained nine patients treated by corneal repair without lens removal. Group C contained 23 patients treated by medical management. Table 3 shows a comparison of the average age, length of corneal laceration, length of lens capsule tear, and time from injury to referral for 47 patients in Category 1, subdivided according to last known success or failure. The average age of patients in Treatment Group A was 2.6 years (range 2 months–7.6 years), Group B was 5.9 years (range 2 months–15.8 years), and Group C was 2.4 years (range 2 months–11 years).

Table 3.   Category 1 was composed of those patients deemed to have potential for vision and it was further subdivided into three treatment groups as follows: (A) corneal repair with lens removal, (B) corneal repair without lens removal, and (C) medical management. Successful treatment outcome was a patient with functional vision restored and having (i) a normal sized globe (relative to the fellow eye), (ii) a positive menace reflex, and (iii) a clear visual axis that allowed detailed funduscopic examination of >50% of the retina. Those patients suffering vision-threatening complications that resulted in blindness or enucleation were considered failures. The average patient’s age, the average length of the corneal laceration, the average length of lens capsule tear, and the average time from injury to referral were calculated for each group. Avg. = average (range; median) n = number of patients with data available
Patients in treatment Groups A–CAgeLength of corneal lacerationLength of lens capsule tearTime from injury to referral (days)
n Avg. (months) n Avg. (mm) n Avg. (mm) n Avg. (days)
Success3138.2 (2–189; 10)304.3 (2–10; 4)276.5 (2–12; 7)312.8 (0.5–14; 1)
Failure1636.8 (2–84; 30)125.5 (2–12; 6)88.6 (5–12; 9)152.1 (0.5–10; 0.5)

The 30 patients in Category 2 consisted of three types, which are as follows: 20 patients with an initial assessment of poor prognosis to restore vision (17 dogs and three cats), five patients with a traumatic cataract diagnosed as an old injury or an incidental finding in an eye with functional vision (four dogs and one cat), and five patients lost to follow up after the initial examination or surgery (four dogs and one cat).

Follow-up time periods of treatment groups

Postinjury follow-up time periods for Treatment Groups A–C were as follows: 1 month, 2–6 months, >6–12 months, >12–18 months, and >18 months; results are summarized in Table 4. Fifteen of the 15 patients in Group A (corneal repair/lens removal) were followed for 1 month, and 13 of the 15 (87%) had functional vision at the time of last examination. Six of 10 patients (60%) followed for 2–6 months had vision at the last examination. Three of the four patients had vision for period >6–12 months, three of the three patients had vision for the period >12 months–18 months, and one of the three patients (33%) followed longer than 18 months had functional vision at the last examination 90 months postinjury (average follow-up 45 months; range 18–90 months). Two patients had functional vision at 18 and 20 months postinjury, but failed to return for follow-up until glaucoma occurred at 72 and 90 months postinjury, respectively. Because these recheck times were clearly outliers among the study population and it was not possible to accurately determine the time for onset of glaucoma, both of these patients were censored at 18 months, the longest follow-up period considered in the analysis. Complications leading to blindness or enucleation included phthisis bulbi (4), secondary glaucoma (2), retinal detachment (2), and endophthalmitis (1). Two patients underwent lens replacement surgery several months after lens removal. Failure occurred in both patients because of phthisis bulbi in one patient (6 months postoperative) and glaucoma in the other patient (54 months postoperative; 72 months postinjury).

Table 4.   Comparison of results in patients with differing follow-up periods. The number of patients in each successive follow-up time period declined because of blindness or patient lost to follow up. The proportion of patients experiencing vision loss at times >18 months in Groups A (67%) and B (100%) was greater than the proportion in Treatment Group C (0%) (P = 0.029 and P = 0.077, respectively)
Treatment group (n = no. of patients)Successful 1 monthSuccessful 2–6 monthsSuccessful >6–12 monthsSuccessful >12–18 monthsSuccessful >18 months
(A) Corneal repair/Lens removal (n = 15)13/15 (87%)6/10 (60%)3/4 (75%)3/3 (100%)1/3 (33%)
(B) Corneal repair (n = 9)8/9 (89%)1/2 (50%)None examinedNone examined0/1 (0%)
(C) Medical  management (n = 23)23/23 (100%)17/21 (81%)15/15(100%)12/12 (100%)12/12 (100%)

In Treatment Group B (corneal repair without lens removal), eight of the nine patients were followed for 1 month, and all had functional vision. Only one of the two patients followed for 2–6 months maintained functional vision at the last examination and the only patient followed longer than 18 months was blind at 26 months postinjury owing to glaucoma. The onset of glaucoma was not possible to accurately determine in this patient as examinations were performed at 3 months and 26 months following injury. None of the nine patients in this group were examined during the >6–12-month and >12–18-month follow-up time periods. The six patients in Group B judged to be successful at the last examination prior to discharge were all censored early (average follow-up 0.8 month; range 1 week–1 month). Three of the six patients censored in Group B were cats, and all feline patients in Category 1 were censored early (average censoring time 1 month; range 0.25–2 months). Two of the three owners of the three canine patients failed to return for re-examination and were censored early.

All 23 patients (100%) in Treatment Group C (medical management) followed for 1 month had functional vision at that time. Twenty-one patients were followed for 2–6 months and 17 (81%) were judged successful during this time period. Fifteen of the 15 patients (100%) followed for >6–12 months had functional vision at last examination, and 12 of the 12 patients followed for the >12–18-month and >18-month time periods maintained vision (average follow-up 31.8 months; range 18–63 months). Seven of the 12 patients followed >18 months were 5 months of age or less. Five of the 12 patients were over 5 months of age (average age 5.4 years; range 0.8–11 years). Two patients in Group C had extensive lens damage, and lens removal was recommended but not elected by the owner. Both patients were successfully managed with medical treatment. (Figs 2a–e and 4a–e). Three patients in this group did not receive the recommended aftercare in the 3-month period following injury and did not return for recommended follow-up examinations until vision-threatening complications developed 2–3 months after the initial examination. Complications leading to blindness or enucleation in the four failures included secondary glaucoma (2), endophthalmitis (1), and phthisis bulbi (1).

Figure 7 shows the Kaplan-Meier plot comparing the probability of maintaining functional vision in different treatment groups as a function of time following treatment. Treatment Groups A and B showed a greater rate of vision loss compared with Treatment Group C (P = 0.029 and P = 0.0097, respectively) that was most obvious >18 months postinjury.

image

Figure 7.  Kaplan-Meier plot comparing the probability of patients maintaining functional vision in the three groups. Treatment Group A (corneal repair with lens removal) and Group B (corneal repair without lens removal) showed a significantly greater rate of vision loss compared to Group C (medical management) that was most obvious >18 months post-injury (P = 0.029 and P = 0.0097, respectively).

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Across the 18-month postsurgical period in both dogs and cats, there was an average overall higher but nonsignificant rate of vision loss in the corneal repair group compared with the medically treated group (HR = 3.0, 95% CI = 0.5–17.9, P = 0.23) and a higher significant rate of vision loss in the lens removal group compared with the medically treated group (HR = 4.5, 95% CI = 1.2–16.7, P = 0.023). These average effects over time were more pronounced in dogs when comparing the corneal repair group with the medically treated group (HR = 13.9, 95% CI = 0.7–277.1, P = 0.085) and the lens removal group compared with the medically treated group (HR = 32.2, 95% CI = 3.7–280.4, P = 0.0017). In addition, however, there was statistical evidence that relative treatment effects on the rate of vision loss were not constant (nonproportional) over the 18-month follow-up period. In dogs and cats together, as well as dogs alone, the effects were most pronounced in the time early following surgery and gradually declined over the ensuing 18 months.

In the aforementioned multivariable models of dogs alone, corneal lacerations because of confirmed or suspected cat claw injuries were associated with a lower (but not significant) rate of vision loss compared with other causes of injuries (HR < 0.01, 95% CI = 0.0–4.2, P = 0.10). Increasing length of the corneal laceration was significantly associated with a lower rate of vision loss (HR = 0.12, 95% CI = 0.012–0.96, P = 0.046). An increasing time interval between injury and referral was significantly associated with a higher rate of vision loss (HR = 24.64, 95% CI = 1.16–524.4, P = 0.040). None of the interactions between treatment group and the other model variables (age, cat claw injury, length of corneal laceration, referral time) were significant. When cats were included in the analysis, findings were qualitatively similar but not significant for cat claw injuries (HR = 0.54, 95% CI = 0.056–5.22, P = 0.60, length of corneal laceration (HR = 0.70, 95% CI = 0.47–1.07, P = 0.098), and referral time (HR = 1.46, 95% CI = 0.90–2.38, P = 0.13).

Descriptive data on prognostic factors

Time interval from injury to referral examination  The time between injury and initial referral examination varied greatly. Thirty-eight of the 77 patients (49.4%) were presented for initial treatment within 72 h of injury and generally had a more favorable prognosis than those presenting more than 2 weeks after injury. Only three of the 38 patients in this group were given a poor initial prognosis because of the presence of glaucoma in one patient, endophthalmitis in another patient, and retinal detachment in the third patient. Twenty of the 77 (26.0%) patients (17 dogs and three cats) were presented at a mean time of 2.3 months (range 1 day–1 year) following injury and determined to have a poor prognosis for vision at initial examination because of the presence of severe uveitis, iris bombe, secondary glaucoma, retinal detachment, and/or suspected intraocular sepsis. All 13 patients referred more than 2 weeks after the injury were given a poor initial prognosis and none recovered vision.

Length of lens capsule tear  The length of the lens capsule tear was at times very difficult to determine as the capsule tear was often obscured by hyphema, fibrin, and/or dense corneal edema at the initial examination/surgery and the only evidence of the capsule tear may have been focal or diffuse traumatic cataract. Careful slit-lamp biomicroscopy was required in most instances to assess the presence of traumatic cataract, and an accurate assessment of the size of the lens capsule tear was often only possible during lens removal surgery or at subsequent examinations of patients treated without lens removal. Only one of the 47 patients in Treatment Groups A–C was documented to have a lens capsule tear <2 mm in length. Accurate measurement of the lens capsule tear was recorded in 35 of the 47 patients (74%) in Groups A–C. This missing data prevented statistical analysis of this parameter. The length of the lens capsule tear was recorded in 20 of the 23 patients (87%) in Group C (medical management) and averaged 6.4 mm (range 3–12 mm). Of the 24 patients treated surgically, the length of lens capsule tear was recorded in 15 patients (63%) and averaged (4.7 mm; range 3–15 mm).

Relationship between the size of corneal laceration and length of lens capsule tear  The size of the corneal laceration was accurately recorded in the medical record or determined from photographs taken at the initial examination in 64 of the 77 patients. Corneal laceration patients were divided into five sizes for analysis, and a comparison of the length of the lens capsule tear was possible in 43 patients (Table 5). On average, the length of the lens capsule tear increased as the size of the corneal laceration increased, but on an individual basis a direct relationship between the size of corneal laceration and the length of lens capsule tear was only observed in patients with large corneal lacerations (>8 mm in length). All lens capsule tears were equal to or greater in length than the corneal wound in these four patients. Conversely, patients with small corneal wounds frequently had large lens capsule tears (Figs 2a–e, 5a–e and 6a–e). The lenses in two patients underwent complete resorption, and both eyes had corneal and lens lacerations exceeding 8 mm in length (one in Group B and one in Group C).

Table 5.   Comparison of corneal laceration size with length of lens capsule tear. On average, the length of the lens capsule tear increased as the size of the corneal laceration increased, but on an individual basis a direct relationship between the size of corneal laceration and the length of lens capsule tear was only observed in patients with large corneal lacerations (>8 mm in length). Only the 43 patients with data recorded for both the corneal laceration and lens capsule tear were used for this analysis
Size of corneal lacerationNo. of patientsLength of lens capsule tear (avg.) (mm)Range (mm)
1–2 mm136.05–12
3–4 mm86.83–12
5–6 mm107.04–8
7–8 mm87.82–12
>8 mm410.710–12

Age of patient  Comparison of results in Treatment Groups A and C was made based on the age of the patient and how this injury may affect the growth of the globe at 1 year of age. Group B was not examined as only two patients were <5 months of age at the time of injury and both were censored at 1 year of age. All three patients 5 months of age or less in Group A were blind at 1 year of age following injury and all showed a prominent decrease in globe size compared with the fellow eye at that time. In contrast, seven of the nine patients (78%) in Group C <5 months of age had functional vision at last examination and none showed a decrease in globe size.

Complications leading to failure

Complications resulting in blindness or enucleation were similar with or without lens removal. Seventy-two of the 77 patients were followed (five lost to follow up), and 36 (50%) patients were categorized as failures. The causes for failure were as follows: secondary glaucoma (11), endophthalmitis (9), phthisis bulbi (6), chronic uveitis/pupillary occlusion (6), retinal detachment (3), and mature cataract (1). These results are summarized in Table 6. The 20 patients that were determined to have a poor prognosis at the initial examination are included in this group. Thirty-six of the 72 (50%) patients had functional vision at last examination (29 phakic and seven aphakic; six lens removal; one complete lens resorption).

Table 6.   Cause of failure
Cause vision loss/eye removalCorneal repair/lens removalCorneal repair onlyMedical managementPoor prognosis at initial examinationTotal
Secondary glaucoma212611
Endophthalmitis1 269
Phthisis bulbi4  26
Chronic uveitis/pupillary occlusion 1 56
Retinal detachment2  13
Mature cataract 1  1
Total9342036

Discussion

  1. Top of page
  2. Abstract
  3. Introduction
  4. Material and Methods
  5. Results
  6. Discussion
  7. Conclusion
  8. References

Clinical significance

Traumatic corneal laceration with associated lens capsule disruption is a serious ocular injury that blinded the eye in 36 of the 72 (50%) patients followed in this report. The recommendation to remove an injured lens is based on the supposition that dogs and cats are often refractory to intensive anti-inflammatory therapy following lens capsule injury.4 This is the first study to report medical management of acute traumatic injuries of this type and clearly refutes this premise. Specifically, 12 of the 12 patients with long-term follow-up (>18 months) in the medical management group presented with significant lens fiber disruption and lens capsule rents averaging 7.3 mm in length (range 4–12 mm), and all were treated successfully (average follow-up time 31.8 months).

The data indicate that long-term follow-up among the treatment groups was superior in the medical management group. Only those patients with good corneal wound apposition and a formed anterior chamber without continued aqueous leakage or uveal prolapse were included in this treatment group. Consequently, patients presenting with good corneal wound apposition and anterior chamber integrity may have a more favorable long-term prognosis for vision than those globes requiring corneal repair or subjected to prophylactic lens removal.

Corneal repair without lens removal was recommended only in patients with poor corneal wound apposition, uveal prolapse, or continued loss of aqueous from the anterior chamber, and it can be conjectured that patients in Group B may have suffered a more serious ocular injury from rapid or prolonged globe decompression. The results in Group B may have been affected by early loss-to-follow-up that occurred in six of the nine patients in this group. This was attributed to a relatively high proportion of feline patients (three of nine) as well as the fact that two of the three remaining canine owners did not return for follow-up. Why feline patients were not returned for follow-up examination is unknown, but this was a consistent finding as none of the five feline patients in Category 1 was followed longer than 2 months.

Dogs and cats may tolerate lens capsule tears without surgery, contrary to previous assumptions, and this may be, in part, due to the fibrinous uveitis that often results. Many patients in this study presented with lens opacities from a combination of traumatic cataract and diffuse opacification of the lens fibers consistent with edema and/or intralenticular neutrophil infiltration. In several patients, the infiltration affected a large portion of the anterior and posterior cortical lens fibers, but usually regressed rapidly and completely resolved in 1–2 weeks with medical therapy. (Fig. 2a–e) The fibrous metaplasia that followed fibrin effusion resulted in closure of the lens capsule tear in most patients within 2–4 weeks of injury. (Figs 2a–e, 3a–d and 4a–e) Two patients exhibited delayed closure of lens capsule defects <3 mm in length and required treatment for low-grade, lens-induced uveitis because of protein extrusion through the capsular tear. (Fig. 5a–e) Both resolved 3–4 months postinjury.

Surgical considerations for len removal

Initially, the decision to remove a traumatized lens in this study was based on previously described clinical recommendations4 and considered necessary to prevent vision-threatening complications associated with phacoclastic uveitis and/or possible latent bacterial infection within the injured lens fibers. All patients with lens capsule tears 2 mm or greater, significant lens fiber disruption, and/or large amounts of lens protein in the anterior chamber were routinely subjected to emergent, prophylactic lens removal in the first 4 ½ years of this study. Of the 13 patients examined during this time with a guarded to good prognosis for vision, only one patient did not fit this criteria and was treated medically. During the latter 6 ½ years of this study, lens removal was only performed in three of the 34 patients presented with a guarded to good prognosis for vision and was based on the severity of the lens injury in two patients and suspected lenticular abscess in the third patient. Lens removal was recommended in two other patients with extensive lens damage, but declined by the owner. Both eyes were managed successfully with medical therapy, and are shown in Figs 2a–e and 4a–e.

The rate of vision loss among the dogs injured by cat claw trauma was lower than other sources of trauma, but was not significant (P = 0.10). The rate of vision loss was significantly higher (P = 0.046) in these patients with small corneal wounds and is attributed to the observation of large lens capsule tears and extensive intraocular trauma in some of these patients. Prognostic factors to discriminate when lens removal is necessary, relative to the size of the corneal laceration, length of lens capsule tear, or degree of lens fiber disruption, were not identified. The size of the corneal laceration only correlated directly with the size of the lens capsule tear in lacerations exceeding 8 mm in length. All four corneal lacerations >8 mm were repaired, two patients had the lens removed and two globes retained vision (one aphakic and one phakic). Even the presence of large amounts of lens material in the anterior chamber did not inevitably result in secondary glaucoma and/or blindness without lens removal. Three patients presented with this condition, and two were successfully managed medically.

Time interval from injury to referral examination

The injured lens healed rapidly (2–4 weeks) with medical therapy, in 17 of the 23 patients, and late complications associated with progressive uveitis/secondary glaucoma or delayed septic endophthalmitis were uncommon in all patients referred within 72 h of injury and followed closely after referral. Dogs with cat claw trauma suffered a significant increase in the rate of vision loss as the time interval from injury to referral increased (P = 0.040). Early recognition of the presence of lens capsule disruption and referral to an ophthalmologist for appropriate medical therapy and/or surgery were crucially important in preventing vision-threatening complications during this critical 2- to 4-week period following injury. Of the 38 patients presented for examination and treatment in the first 72 h following eye injury, only 3 (7.9%) were considered to have a poor prognosis for vision (retinal detachment, endophthalmitis, and glaucoma). The average time between injury and referral in the 20 patients presented initially and deemed to have a poor prognosis was 75 days (range 1 day–1 year). It can be conjectured that these patients give a false impression that all patients with lens capsule tears 1.5 mm or greater will certainly develop vision-threatening complications unless early lens removal is performed.

Age as a prognostic factor

This type of eye injury has been previously reported to be common in adolescent patients,1,4 and similarly in this study, 35 of the 77 patients (45.5%) were adolescent (<1 year of age), while 26 of the 77 (34%) were 5 months of age or younger at the time of injury. However, cats were generally much older than dogs and only two of the 10 were adolescents. The canine globe is considered adult-like in function by 2–3 months of age with continued growth for the first year, but most of the increase in axial globe length occurs during the first 5-month postnatal period.7–10 Several animal studies suggest that the lens may be a source of essential growth factors for the eye, and lens removal in young rabbits, chicks, and monkeys has been theorized to result in the retardation of eye growth as a consequence.11–14 The loss of these trophic factors may have contributed to decreased globe growth observed at 6 months postinjury in all three patients <5 months of age at the time of lens removal, although regression analysis of the three treatment groups did not show patient age to be a significant factor.

Population characteristics

Exophthalmic, brachycephalic, and Terrier breeds were well represented in the canine population, as were small breed dogs. Female patients (sexually intact and spayed) outnumbered male patients (sexually intact and neutered) by over a 2 to 1 margin overall and among the cat claw injury patients. This significant sexual predilection for this type of injury among the females was unexpected and not previously reported.

Previous clinical studies

Clinical studies are lacking prior to 2005 of patients presented acutely following corneal laceration with lens capsule tears 2 mm or greater in length and treated without lens removal.1,4,5 In the first clinical case study of 13 dogs and cats suffering traumatic lens capsule disruption by Davidson et al., early prophylactic lens removal was recommended if the lens capsule tear was 1.5 mm or greater and/or was accompanied by substantial disruption of underlying lens cortex. This conclusion was based on the observations regarding one patient in this study, followed for 5 years, with a lead pellet embedded in the lens cortex through a 1.5-mm lens capsule entry wound.4 The recommendation to remove those lenses with traumatic capsule tears 1.5 mm or greater is frequently referenced15–18 and was corroborated by a subsequent study involving 17 dogs with cat claw eye injuries.5 Retrospective studies of human lens capsule injuries have documented high morbidity with late lens removal or medical management,19–21 and lens removal remains a common treatment following this type of injury in people.22

In the retrospective review by Davidson et al.,4 early referral was considered integral to successful management and preservation of vision, but the assessment of long-term outcome of lens removal patients was not possible as the follow-up period was brief (1–2 months). Davidson et al. reported that six of the 7 (86%) patients were successfully managed during short-term follow-up with elective lens removal as did this study with 13 of the 15 (87%) lens removal patients successful at 1-month follow-up. Furthermore, previous case studies of dogs and cats do not allow for definitive statements regarding acute medical therapy as those patients with a good prognosis for vision were routinely subjected to prophylactic lens removal.4,5 A previous histopathology study of 20 eyes examined for intractable inflammation and/or secondary glaucoma because of lens capsule rupture supported the hypothesis that early lens removal may be the best and only successful treatment for an injured lens.1 Severe uveitis and/or secondary glaucoma, nonresponsive to intensive medical therapy, are often cited as the cause of blindness in animals treated without lens removal.1,4,23,24

The preliminary data presented by this author of the first 38 clinical cases showed that young patients (6 months of age or less) had a much higher success rate when treated without lens removal compared with those treated with lens removal (100% vs. 25%, respectively).25 The preliminary data suggested that older patients may require lens removal more frequently for successful results, but was disproven by the completed study. In fact, five of the 12 patients in Treatment Group C with long-term follow-up (>12 months) were older than 6 months of age (average age 5.4 years; range 0.8–11 years). The current study provides evidence that patients of all ages may be managed without prophylactic lens removal.

Advances in pharmacology

The success of medical management of patients with traumatic lens capsule disruption in this study may be attributable to improved drug therapy in recent years. Two previous case studies have shown that complications developing from latent infections may occur months to years after this type of ocular injury, resulting in enucleation.2,3 Septic implantation syndrome is the nomenclature proposed to describe the delayed endophthalmitis that may result and is typified by the presence of intralenticular bacterial colonies, usually Gram-positive cocci, in the histopathology specimens.2,3 Similar findings have recently been reported in people with similar ocular injuries.26 Bacterial endophthalmitis has also been reported to occur quickly following penetrating lens injuries.15

Fluoroquinolone antibiotics have been shown to have broad spectrum of efficacy against a wide variety of bacterial ocular pathogens. Ofloxacin administered topically penetrates through an intact corneal epithelium and has been shown to achieve aqueous humor concentrations that exceed the MIC90 of most common ocular pathogens in the dog.27 This may explain the low incidence of delayed bacterial endophthalmitis or septic implantation syndrome in this study. Bacterial endophthalmitis was suspected in one of the 32 patients managed without lens removal, but could not be confirmed as the referring practitioner performed the enucleation and histopathology was not performed. The topical administration of ofloxacin 0.3% (Ofloxacin Ophthalmic Solution 0.3% USP; Ethicon) was the antibiotic of choice in most patients and prescribed in 25 of the 32 patients treated without lens removal (Treatment Groups B and C). Septic implantation syndrome was suspected in eight patients (six dogs and two cats) in this study, but six of the eight patients (five dogs and one cat) were in the group of 20 patients given a poor prognosis at the initial examination.

Experimental studies utilizing the laser anterior capsulotomy model of ocular inflammation have demonstrated the efficacy of nonsteroidal anti-inflammatory drugs in the dog. Flurbiprofen dramatically decreased intraocular inflammation and prevented miotic response compared with prednisolone acetate 1% ophthalmic suspension and systemically administered prednisolone, which were ineffective in comparison.28 Diclofenac was more effective, experimentally, in stabilizing the blood–aqueous barrier of the canine eye when compared with flurbiprofen, tolmetin, and suprofen29 and was used preferentially in the first 4 years of this study. Ketorolac tromethamine ophthalmic solution significantly reduced the intraocular inflammation in humans following cataract surgery and was considered comparable in ocular anti-inflammatory capability to diclofenac.30 Ketorolac 0.5% (Ketorolac Tromethamine Ophthalmic Solution 0.5%; Falcon Pharmaceuticals) or diclofenac 0.1% (Diclofenac Sodium Ophthalmic Solution 0.1%; Falcon Pharmaceuticals) were the only two nonsteroidal anti-inflammatory ophthalmic medications prescribed routinely in all patients in this study, with or without lens removal, and were considered indispensable in preventing sequelae associated with progressive miosis, pupillary seclusion, and secondary glaucoma.

Study limitations

The lack of randomization of the patients into various treatment groups is a limitation of the current study owing to its retrospective nature. The spectrum of ocular injury, from minor to more serious, did not change over the course of this study. However, the great variability in the ocular injuries as well as the wide variation in time from injury to initial presentation dictated that not all patients were treated the same. Standardized therapeutic regimens prescribed in patients undergoing elective lens removal are not suitable in the clinical management of ocular injuries of this type and spectrum. Recommended recheck intervals were similar, and the clinical management was often adjusted empirically according to the patient’s response. The inability to accurately determine the length of the lens capsule tear in some patients prevented statistical analysis of this important variable. Aftercare of patients during the first 3 months following injury was considered critically important regardless of the type of therapy received. Poor owner compliance with medical therapy and/or failure to return at recommended follow-up times during this time period was relevant and may have been a factor in three of the four patients that failed in Group C (medical management) as well as one of the three failures in Group B. None of the nine failures in Group A was attributed to poor owner compliance, although two of these failures were the result of glaucoma that developed 6 and 7.5 year’s postinjury.

Conclusion

  1. Top of page
  2. Abstract
  3. Introduction
  4. Material and Methods
  5. Results
  6. Discussion
  7. Conclusion
  8. References

Lens removal remains an accepted, necessary procedure for patients with lens injury in certain circumstances; however, emergent, prophylactic lens removal is not required, in most patients, to avoid complications associated with the intraocular release of lens protein. The results of this study demonstrate that medical management is an appropriate therapy for patients of all ages suffering perforating corneal injuries with associated lens capsule disruption. Patients with corneal injuries requiring surgical repair or managed by lens removal following corneal repair suffered vision-threatening complications approximately 3–4.5 times the rate of patients treated by medical management, respectively. The length of the corneal laceration and time interval from injury to referral were relevant prognostic factors. Among the dogs with cat claw injury, a significantly higher rate of vision loss was noted as the length of the corneal laceration decreased and/or as the time interval between injury and referral increased. Favorable prognostic signs for treatment by medical management include good corneal wound apposition and a formed anterior chamber without uveal prolapse or continued aqueous leakage.

References

  1. Top of page
  2. Abstract
  3. Introduction
  4. Material and Methods
  5. Results
  6. Discussion
  7. Conclusion
  8. References
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