Front of Eye

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The future for cataract surgery. How and by whom?

The prevalence of cataract is strongly age-related and cataract surgery is one of the most commonly performed surgical procedures in developed countries. With life expectancy in these countries increasing, there is a resultant increase in the pool of people needing cataract surgery. For example, life expectance in Australia by the beginning of the next century is expected to increase to between 88 and 96 years for females and between 85 and 93 and for males.[1] A Canadian report [2] suggests that the need for cataract surgery in Canada, the United States, United Kingdom and Australia will more than double in the next 25 years. Because of the long training time needed to graduate ophthalmologists, the logistics of providing sufficient cataract surgeons should be faced now. This raises interesting questions. Will cataract surgery be performed in much the same manner in 25 years time and only by full-spectrum ophthalmologists or will there be technical advances that make the procedure simple enough to be performed by ophthalmic clinicians or even by robotic surgery or perhaps purely medical means?

  • 1
    Australian Bureau of Statistics. 322.0 Population Projections, Australia, 2006 to 2101. 04/09/2008.
  • 2
    Hatch WV, Campbell Ede L, Bell CM, El-Defrawy SR, Campbell RJ. Projecting the growth of cataract surgery during the next 25 years. Arch Ophthalmol 2012; 130: 14791481.

Corneal hairs and spiders

Arachnophobia or the fear of spiders is not uncommon and although the Oxford Shorter Dictionary has no entry ‘arachnophile’, there are people who keep spiders as pets and clubs that organise exhibitions of their more exotic species. A case is reported of a child, who developed corneal irritation after handling a Chilean Rose tarantula at such an exhibition. Examination revealed microscopic hairs embedded at all levels of the cornea. Other reports have noted ocular complications including conjunctivitis, kerato-uveitis, pan-uveitis with chorioretinitis and general symptoms of dermatological and respiratory involvement. Tarantulas have a defence that involves the spider rearing up to allow rubbing of urticating (sharp stinging) abdominal hairs that are then flicked toward the attacker. These hairs are barbed, sharp and prolific: a spider typically having 10,000 per mm2 urticating hairs.

  • McAnena L, Murphy C, O'Connor J. ‘Tarantula Keratitis’ a case report. J Med Sci 2012 Dec 5. [Epub ahead of print].

Blood and tears defeat the bugs

The external anterior eye is a warm, moist and largely exposed region subject to an environment containing bacteria. Although an ideal bacterial host tissue, the relative rarity of serious infection of the cornea and conjunctiva has been found to be partly due to keratin containing anti-microbial proteins expressed by corneal epithelial cells. The authors of this study[3] suggest that these keratin-derived anti-microbial cytokeratins may have promise as therapeutic agents at other sites. Moll's glands, the secretory glands of the eyelids are modified aporcrine sweat glands that are present in limited areas of the human body, such as armpits, nipples and the genito-anal region. They are believed to have a role in repair of skin wounds and corneal epithelium disruption. Eccrine sweat glands are more widely distributed than the aporcrine form and are more numerous in humans. They continuously secrete the epithelial basal cells of the normal epidermis. Following skin wounding, there is a marked increase in the production of these basal cells that migrate outward, changing to form the healed skin. The function of eccrine sweat glands may provide insight to the general process of healing.[4]

  • 3
    Tam C, Mun JJ, Evans DJ, Fleiszig SMJ. Cytokeratins mediate epithelial innate defense through their antimicrobial properties. J Clin Invest 2012; 122: 113.
  • 4
    Rittié L, Sachs DL, Orringer JS, Voorhees JJ, Fisher GJ. Eccrine sweat glands are major contributors to reepithelialization of human wounds. Am J Path 2013; 182: 163171.

Mind your IOPs after LASIK

Laser in situ keratomileusis (LASIK) changes the shape of the cornea with thinning of the cornea and of course, the intended change in refraction. What else does it change? A study compared pre-operative intraocular pressure (IOP) with post-operative findings at two months post-operative that are believed to be due to the thinning of the cornea rather than a true increase in IOP. This finding should alert the practitioner to possible masking of a true rise in IOP after LASIK surgery.

  • Shousha SM, Abo Steit MA, Hosny MH, Ewais WA, Shalaby AM. Comparison of different intraocular pressure measurement techniques in normal eyes, post surface and post lamellar refractive surgery. Clin Ophthalmol 2013; 7: 7179.

A pox on your front chamber

Approximately one in four people will experience a re-activation of varicellar herpes virus (the cause of childhood chicken pox) to cause herpes zoster, usually after age 50 with increasing prevalence with advancing age. Uveitis is significantly more common in the 12 months following herpes zoster than in age-matched controls, suggesting that people having this painful condition should be monitored for uveitis during this period.

  • Wang T-J, Hu C-C, Lin H-C. Increased risk of anterior uveitis following herpes zoster. Arch Ophthalmol 2012; 130: 451455.

Dominance and the odd raised eyebrow

Blepharoplasty involves surgery to reshape the eyelids to alter the appearance for cosmetic reasons or to improve tear flow. A study involving patients, who had bilateral upper eyelid blepharoplasty and asymmetric eyebrow elevation tested for ocular dominance. It was found that involuntary asymmetric elevation of the eyebrows is strongly associated with ocular dominance.

  • Shah CT, Nguyen EV, Hassan AS. Asymmetric eyebrow elevation and its association with ocular dominance. Ophthal Plast Reconstr Surg 2011; 28; 5053.

Back of the Eye

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Is sunlight really a risk for AMD?

Sunlight exposure has been linked with development of age-related macular degeneration (AMD) and although the evidence is somewhat tenuous, the belief has been a boon to manufacturers and suppliers of sunglasses and other protective eyewear. A systematic review of fourteen studies testing this causal association found that the pooled data provided a protective odds ratio of 1.397 but with wide confidence intervals, suggesting that more evidence is required to reliably confirm the association. Maybe this is something people with an interest in selling sunglasses do not want to know.

  • Sui GY, Liu GC, Liu GY, Gao YY, Deng Y, Wang WY, Tong SH et al. Is sunlight exposure a risk factor for age-related macular degeneration? A systematic review and meta-analysis. Br J Ophthalmol 2012 Nov 10. [Epub ahead of print].

Radiotherapy for AMD out of favour

A Cochrane review of fourteen trials reported the outcome of external beam radiotherapy for neovascular age-related maculopathy (ARM). The reviewers found inconsistency between trial results and identified risk of bias because of difficulty in masking the treatment and control groups. Although most studies found small positive treatment effects, some were not statistically significant. One study found a (non-significant) favourable outcome in the control group. The review authors conclude that the evidence does not support the use of radiotherapy as an effective treatment for neovascular ARM.

  • Sivagnanavel V, Evans JR, Ockrim Z, Chong V. Radiotherapy for neovascular age-related macular degeneration. Cochrane Database Syst Rev 2010: CD004004.

Retinopathy takes hold in US

The four leading causes of non-refractive visual impairment (NRVI) in the United States are age-related macular degeneration, glaucoma, cataract and diabetic retinopathy with diabetic retinopathy being a major cause in all age groups. A recent US study reported the relative prevalence of non-refractive visual impairment association with systemic disease and socio-economic conditions. The identified risk factors were age, poverty and diabetes, especially diabetes of long duration, lower education achievement and lack of medical insurance. It might be expected that visual complications associated with diabetes would have decreased with improved systemic and ocular treatment. This was not confirmed by the results of the study, suggesting that there is a deficiency in the overall management of diabetes or that any improvement in management is overshadowed by an increase in prevalence and longer duration of diabetes due to earlier diagnosis and longer life expectancy.

  • Ko F, Vitale S, Chou C-F, Cotch MF, Saaddine J, Friedman DS. Prevalence of non-refractive visual impairment in US adults and associated risk factors, 1999-2002 and 2005-2008. JAMA 2012; 308: 23612368.

Odds and Ends

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  2. Front of Eye
  3. Back of the Eye
  4. Odds and Ends

Women contributing to ophthalmic science

Women have long practised as ophthalmologists, (vide ophthalmologist Ida Mann 1893-1983) but with a few notable exceptions, do not contribute as principal authors to the ophthalmological literature or until recent years, serve on editorial boards of ophthalmic journals. A historical survey of three leading American ophthalmological journals showed that no female has ever served as Editor-in-Chief of these journals but there has been an increase in Editorial Board members from 3.3 per cent in 1969 to 18.8 per cent in 2009. Women listed as lead author in research papers increased from eight per cent in 1969 to 56 per cent in 1999. The increase in female first authorship has paralleled the increase in the number of female ophthalmologists. The means of determining the sex of authors is outlined in the methods section of the report. The authors note that women tend not to practise medicine in the same manner as men by selecting specialities that favour family friendly hours. This trend appears to be changing, as more women physicians than their male counterparts have never married or are divorced. The equilibrium between numbers of male and female ophthalmologists is closing, as is their representation in ophthalmic research and publishing.

  • Mansour AM, Shields CL, Maalouf FC, Massoud VA, Jurdy L, Mathysen DGP, Jaafar D et al. Five-decade profile of women in leadership positions at ophthalmic publications. Arch Ophthalmol 2012; 130: 14411446.

I do not do as I say. Are we honest with ourselves?

The validity of results of a questionnaire-based survey depends on a number of factors including that of self-reporting bias. Respondents tend to provide answers that are influenced by perceived conformity to expected values. A UK study measured the validity of self-reporting of glaucoma case management by optometrists. Incognito investigators, trained to identify aspects of a standard eye examination, visited a sample of thirty-four optometrists and recorded the test procedures used. Unaware of the earlier investigation, the optometrists were interviewed face-to-face as to their case management of glaucoma suspects. There was considerable failure of agreement between the questionnaire results and the pseudo-patient reports in clinical areas of history taking including symptoms, intraocular pressure recording and visual field studies.

  • Khan S, Clarke J, Kotecha A. Comparison of optometrist glaucoma referrals against published guidelines. Ophthalmic Physiol Optics 2012; 32; 472477.

Exophoria equals extravert?

Folk law in optometry and fiction have long associated a person's personality with the refraction and/or phoria. A questionnaire-based study involving 54 student optometrists sought refractive and heterophoric measurements and used a Myers-Briggs personality survey to seek an association. No significant relationship between personality and refractive error or phoria was found. Surprise!

  • Godtland R. Investigation into the relationship between vision and personality. J Behav Optom 2012; 23: 5962.