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Driving Performance of Patients With Bilateral Glaucoma
June 2016
To assess the effect of glaucoma on driving performance, Bhorade et al. conducted a case-control study comparing patients with glaucoma against normal controls. They found that glaucoma patients had a significantly higher rate of unsafe on-road driving and required more interventions from the accompanying driving instructor.
This study included 21 patients with bilateral moderate or advanced glaucoma and 38 controls with no ocular disease; all participants were between ages 55 and 90. Participants underwent a variety of baseline assessments, including visual acuity (VA) and visual field (VF), tests of psychological and cognitive status, hand grip strength, neck range of motion, and ability to read and understand road signs. Each participant then took a driving test on a defined 13-mile course on city streets, accompanied by a driving instructor in the front passenger seat and a driving evaluator in the backseat. The evaluator did not know the driver’s visual status, although—for safety reasons—the instructor did. The same instructor and evaluator accompanied all participants, and the same car (with dual brake controls) was used in all tests. Overall driving performance of pass versus marginal/fail and the number of wheel or brake interventions were recorded.
The researchers found that the glaucoma group had a significantly higher percentage of marginal/fail performance than the controls (52% vs. 21%, respectively; odds ratio [OR] 4.1) as well as a higher risk of wheel interventions (OR, 4.67). Paradoxically, among the glaucoma patients, there were no significant differences in VA, VF, contrast sensitivity, or glare testing between those who passed and those who scored marginal/fail. However, the glaucoma patients in the marginal/fail group had worse scores on several psychometric and physical measures such as Trail Making Tests A and B, sign reading, grip strength, rapid walking, and brake response time.
The authors commented that the 48% of glaucoma patients who passed the driving test were most likely using strategies such as saccadic eye movements and head movements to compensate for their visual impairment. The researchers concluded that approximately half of patients with moderate or advanced glaucoma are at risk for unsafe driving—particularly those with worse performance on psychometric and mobility tests—while the other half may be safe drivers.
Photodynamic Therapy to Inhibit MRSA Keratitis Isolates
June 2016
In this in vitro study, Halil et al. examined the effect of photodynamic therapy (PDT) using 2 different photosensitizers—riboflavin or rose bengal—on multidrug-resistant isolates of methicillin-resistant Staphylococcus aureus (MRSA). Although both PDT regimens inhibited MRSA, the researchers found that rose bengal was more effective.
Bacterial inocula were obtained from the corneas of 2 patients with chronic exposure keratitis that did not respond adequately to treatment with multiple antibiotics. The inocula were cultured on agar plates and exposed for 30 minutes to different regimens of PDT: UV-A light with 0.1% riboflavin photosensitizer (as used in corneal cross-linking) or green light with 0.03% or 0.1% rose bengal photosensitizer. All 3 preparations were also tested in darkness and ambient light conditions; in addition, irradiation with UV-A or green light alone (no photosensitizer) was evaluated. The agar plates were photographed 72 hours after exposure, and custom software was used to measure bacterial inhibition.
Complete growth inhibition of both MRSA strains was demonstrated (1) for both rose bengal concentrations under ambient and green LED irradiation, and (2) for the 0.1% rose bengal in the dark. The 0.03% rose bengal in dark conditions showed complete inhibition of strain 2 but incomplete inhibition of strain 1. Riboflavin showed almost complete inhibition with UV-A irradiation, but it had minimal effect in dark and ambient light conditions. In irradiation-only exposure, UV-A achieved 79% inhibition for MRSA-1 and 81% inhibition for MRSA-2. For green light, the inhibition percentages were 50% and 28%, respectively.
The researchers concluded that, compared with topical antibiotics, PDT could prove advantageous in treating bacterial keratitis; moreover, rose bengal—approved for use on the ocular surface as a staining agent—was effective across a wide range of light conditions.
Refusal of Surgical Treatment for the Fellow Eye in CIGTS
June 2016
Gupta et al. examined the factors associated with refusal of second-eye trabeculectomy among patients in the Collaborative Initial Glaucoma Treatment Study (CIGTS). They found that lower intraocular pressure (IOP) in the second eye and hypotony after surgery in the first eye were most strongly linked with refusal.
This study was a post hoc analysis of data collected in the CIGTS, a trial initiated in 1989 to compare outcomes in patients initially treated with medication versus trabeculectomy. Of the group randomized to surgical treatment in the study eye, 159 were eligible for fellow-eye surgery, either at baseline or later. Of those 159 patients, 30 (18.9%) refused trabeculectomy on the second eye, although some did receive treatment with trabeculoplasty or medication.
To understand the reasons for refusal, the investigators considered a wide range of baseline demographic factors, intraoperative issues (e.g., type of anesthesia or occurrence of complications), and postoperative complications (e.g., inflammation or corneal problems). Although several of these factors, especially those relating to intraoperative or postoperative complication, occurred at a higher rate among patients who refused surgery, the only factors that remained statistically significant after multivariable analysis were a lower IOP in the fellow eye and hypotony in the eye that had received trabeculectomy.
The authors acknowledged several potential weaknesses of the study. Most notably, the treatment regimens used in the CIGTS do not reflect current practice, and the number of patients refusing surgery was too small to attain statistical power in assessing many of the factors.
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American Journal of Ophthalmology summaries are written by Peggy Denny and edited by Richard K. Parrish II, MD.
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