High-risk characteristics of fellow eyes of patients with unilateral neovascular age-related macular degeneration.

OBJECTIVE

This study aimed to determine whether clinical tests of ocular function and macular appearance independently can help to predict which patients with unilateral neovascular age-related macular degeneration (AMD) will have a choroidal neovascular membrane (CNVM) develop in their fellow eye.

DESIGN

The study design was a prospective cohort study.

PARTICIPANTS

One hundred twenty-seven patients with unilateral neovascular AMD observed for up to 4.5 years participated.

INTERVENTION

Functional measurements included visual acuity, macular visual field, glare recovery time, and foveal electroretinogram amplitude and implicit time.

MAIN OUTCOME MEASURE

The age-adjusted proportion of patients having a CNVM develop over follow-up assessed by the Cox proportional hazards model with stepwise selection was measured.

RESULTS

On average, 8.8% of patients had a CNVM develop each year. Independent risk factors for the fellow eye were its glare recovery time in minutes (relative risk = 1.30, confidence interval = 1.10-1.54, P = 0.003) and its extent of visible macular abnormalities on a four-point scale (relative risk = 1.62, confidence interval = 1.06-2.59, P = 0.03). Of the fellow eyes that converted, the interval to have a CNVM develop was inversely related to the foveal electroretinogram implicit time.

CONCLUSIONS

A slower recovery from glare and more extensive funduscopic changes appear to be independent risk factors for the development of a CNVM in the fellow eyes of patients with unilateral neovascular AMD. A slower foveal electroretinogram implicit time may be a sign of early stage CNVM development, perhaps because of outer retinal ischemia. These results have clinical management implications, particularly for those patients at high risk of having a potentially treatable form of AMD develop.