Enlargement of atrophy and visual acuity loss in the geographic atrophy form of age-related macular degeneration

Objective: To describe the progression of geographic atrophy (GA) from age-related macular degeneration (AMD) with respect to visual acuity (VA) loss and enlargement of atrophy. Design: A prospectively observed case series. Setting: Tertiary retinal referral center. Participants: One hundred twenty-three patients with GA due to AMD who completed at least 1 year of follow-up (median follow-up, 3 years) were examined annually. Methods: At each examination, a protocol best-corrected VA of each eye was measured, a clinical examination was performed, and color fundus photographs were taken. The areas of atrophy were drawn and measured. Main Outcome Measures: Visual acuity loss and enlargement of total and central atrophy. Results: At baseline, median VA was poorer with larger areas of atrophy, but there was wide variation related to sparing of the fovea. Thirty-one percent of all study eyes suffered a three-line VA loss from baseline by 2 years, and 53% had a three-line loss by 4 years. Those eyes with VA better than 20/50 had the highest rate of acuity loss; 27% of these eyes had acuities of 20/200 or worse at 4 years. Visual acuity loss in the GA study eye was similar in patients with bilateral GA and in those with choroidal neovascularization in the fellow eye. Total atrophy enlarged a median of 1.8 Macular Photocoagulation Study disc areas (DA) at 2 years; atrophy within a 4-DA circle centered on the fovea enlarged a median of 0.9 DA. Two (22%) of nine patients with GA in one eye and only drusen without advanced AMD in the fellow eye developed GA in the fellow eye at 2 years. Conclusions: Geographic atrophy is associated with a significant decline in VA over time in many eyes. Areas of atrophy continue to enlarge over time, even when already large at baseline. The combination of reduced VA with enlargement of atrophy, occurring bilaterally in most patients, can lead to significant impairment of visual function.