Journal, June 2002

From the July Issue of Ophthalmology

By Lori Baker Schena, Contributing Writer

Edited By Brian A. Francis, MD

Early Age-Related Maculopathy Puts the Brakes on Night Driving

Patients in the early stages of age-related maculopathy—even when the fellow eye has relatively good acuity (20/60 or better)—are more likely to experience difficulty in night driving, problems with near vision activities and glare disability than are similarly aged adults who enjoy normal retinal health, report Scilley et al.

And for those individuals with early ARM whose vision in the fellow eye is worse than 20/60, these effects are greater and more widespread, involving other visual tasks including day driving.

In this study, the investigators conducted tests of visual acuity and scotopic sensitivity on 92 adults with early ARM and a reference group of 55 older adults in the same age range with normal eyesight. The subjects were also given a general health questionnaire.

Results indicated that night driving—a low luminance activity—appears to be among the most seriously hampered tasks in early ARM from the patients’ perspective. Interestingly, these reports of night driving difficulty were linked to scotopic sensitivity impairment.

The researchers note that the emergence of night driving problems in these patients, even when acuity is relatively good, may be an early functional manifestation of the ARM disease process.

They conclude that health-related quality of life instruments designed to evaluate treatments for early ARM should address not only near and far tasks that rely on good acuity but also activities performed under low luminance conditions.

Long-Term Effects of Primary Mitomycin C Trabeculectomy

Bindlish et al. report some “good news/bad news” findings in their five-year follow-up study of primary trabeculectomy with mitomycin C.

The good news: Even after five years, MMC significantly lowers IOP and reduces the number of prescribed antiglaucoma medications.

The bad news: Their results suggest a higher cumulative incidence of late-term hypotony.

In this retrospective, noncomparative interventional case series, 123 eyes underwent standard primary trabeculectomy performed by one of two surgeons using a Weck cell pledget soaked in MMC at a concentration of 0.25, 0.33 or 0.5 milligrams per milliliter for 30 seconds to five minutes. Laser suture lysis was performed postoperatively for IOP control. Mean preoperative IOP was 25.79 mmHg, and year five postoperative IOP was 9.91 mmHg. Hypotony occurred in 42.2 percent of eyes 26.1 months postoperatively.

One predictor for late term hypotony was IOP at first postoperative month—the lower it was, the higher the risk for delayed hypotony. Race also proved a predictor for the development of hypotony with the condition five times more prevalent in whites than in blacks.

The investigators conclude that MMC must be used with caution in primary trabeculectomy, particularly in young white patients.

Guidelines Proposed for Repair of Isolated Orbital Floor Fractures

Based on his meta-analysis of a literature review, Michael A. Burnstine suggests guidelines for repair of isolated orbital floor fractures.

Although no randomized prospective reports or case series were found, his Medline search of articles published since 1983 identified 64 relevant papers.

The evaluation and subsequent management of such patients includes the following integral components:

a careful history,
a thorough physical examination and
coronal computed tomography scans.

Immediate surgical repair is indicated by:

nonresolving oculocardiac reflex due to pulling on a rectus muscle (a life-threatening bradycardia, heartblock, nausea, vomiting, syncope),
the “white-eyed” blowout fracture(a trap-door fracture with herniating orbital tissue into the fracture causing pain and diplopia with a quiet globe)
and
early enophthalmos or hypoglobus.

Surgery within two weeks is recommended in cases of symptomatic diplopia with positive forced ductions and evidence of an entrapped muscle or perimuscular soft tissue on CT examination and may also be required within this period for large orbital floor fractures that may cause latent enophthalmos or hypo-ophthalmos.

Transplantation of Cultivated Corneal Epithelium Queried

In the treatment of severe limbal stem cell dysfunction, the success rate of transplantation of human limbal epithelium cultivated on amniotic membrane is no different from conventional limbal and AM transplantation, according to Shimazaki et al.

In this study, 13 eyes of 13 patients with severe limbal deficiency (Stevens-Johnson syndrome in eight eyes, ocular cicatricial pemphigoid in three eyes and chemical burns in two eyes) underwent transplantation of cultivated allo-limbal epithelium on their ocular surface. The corneal epithelium cultivated on AM formed two to three layers, as well as basement membrane-like structures.

Postoperatively, the epithelium regenerated and covered the ocular surface in eight eyes. However, three of the eight eyes developed partial conjunctival invasion, and two other eyes later developed epithelial defects. Ultimately, six eyes achieved corneal epithelialization, five eyes had conjunctivalization, one eye had dermal epithelialization and one eye was not epithelialized.

As for complications, corneal perforation developed in four eyes, and infectious keratitis in two.

The authors conclude that this treatment approach does not improve the surgical prognosis for patients with severe limbal stem cell dysfunction and that further refinements in the technique may be necessary.

Round-up Peer-reviewed Literature

By Lori Baker Schena, Contributing Writer

Edited By Jose S. Pulido, MD, MS, MBA

Gender, Retinal Arteriolar Narrowing Are Linked to Coronary Heart Disease

Journal of the American Medical Association 2002;287:1153–1159

Retinal arteriolar narrowing is related to risk of coronary heart disease in women but not in men, report Wong et al.

As part of the Atherosclerosis Risk in Communities Study, an ongoing prospective population-based cohort study, retinal photographs were taken in 9,648 women and men between the ages of 51 and 72 who didn’t have CHD.

During a 3.5-year follow-up period, 84 of the women and 187 of the men experienced CHD events.

In women, decreasing retinal arteriolar diameters were associated with increasing risk of CHD, even after adjusting for other risk factors.

In men, however, the arteriolar narrowing wasn’t associated with risk of any incident CHD.

The researchers conclude that this study offers key information into differences in the epidemiology and pathogenesis of CHD between women and men—suggesting that microvascular processes may play a greater role in the risk of CHD in women. Future work is needed to confirm these findings.

The Pharmaceutical Industry and Clinical Practice Guidelines

Journal of the American Medical Association 2002;287:612–617

Choudhry et al. tackled the task of quantifying the extent and nature of interactions between authors of clinical practice guidelines and the pharmaceutical industry.

Approximately half of the 192 authors identified by the researchers responded to a cross-sectional survey. These authors published CPGs between 1991 and 1999 that were endorsed by North American and European societies.

The investigators found that:

87 percent of the authors had some form of interaction with the pharmaceutical industry,
58 percent had received financial support to perform research,
38 percent had served as employees or consultants of a pharmaceutical company and
59 percent had relationships with companies whose drugs were considered in the CPGs they authored. Of those, 96 percent had relationships that predated the guideline creation process.

While the majority of responding authors believed that their relationships had no influence on the recommendations included in the CPGs, the investigators conclude that their findings raise several issues.

They provide recommendations for the management of potential financial conflicts of interest for these authors—calling for appropriate disclosure and a formal process for discussing these conflicts prior to the development of CPGs.

Dry Eye Significant in LASIK for Hyperopia

Journal of Refractive Surgery 2002;18:113–123

Dry eye is a significant side effect of hyperopic LASIK, and women are at greater risk of developing chronic dry eye symptoms and refractive regression after this procedure, report Albietz et al.

Dry eye symptoms occur despite extensive measures to protect and restore the tear film and ocular surface before, during and after surgery with abundant use of nonpreserved lubricants, minimal use of preserved medications and supplementary use of punctal plugs and lid hygiene procedures.

The investigators conducted a 12-month analysis of 88 eyes of 88 participants who had LASIK for hyperopia, following up at two weeks and at one, three, six and 12 months. Results showed that 32 percent of participants experienced chronic dry eye symptoms that lasted six months or more.

The authors conclude that additional strategies must be developed to restore tear film and ocular surface integrity following LASIK. This would go a long way in helping prevent chronic dry eye symptoms, tear film insufficiency and instability, ocular surface disruption and refractive regression.

Understanding of Visual Development Improves Outcomes

Journal of Pediatric Ophthalmology & Strabismus 2002;39:69–72

A CME review article by Olitsky et al. highlights how a greater understanding of visual development in humans has led to a shift in amblyopia treatment approaches, specifically concerning the removal of a monocular cataract during infancy.

Before data were gathered concerning the sensitive period of visual development in humans, monocular cataracts generally were not removed until the child was 6 months or older.

However, a new understanding about this sensitive period—which comes from basic neuroscience laboratory research—has prompted surgeons to remove cataracts in the first few weeks of life with significantly improved outcomes.

Unfortunately, neither the start of this critical period of visual development nor its ending point has been precisely defined. Some data indicate that the critical period may not begin until at least 6 weeks of age, and this period may not be uniform for all visual functions. Most ophthalmologists agree the critical period ends around the time a child is 9 years old, although it may be later than that.

The authors call for further research to pinpoint this time period, which would enhance treatment alternatives for amblyopia.