Comparable Growth Rates of Bilateral Geographic Atrophy due to Age-related Macular Degeneration

Abstract

Purpose : To evaluate growth rate and characteristics of bilateral geographic atrophy (GA) associated with age-related macular degeneration (AMD) from fundus color and autofluorescence images

Methods : We evaluated fundus photographs (FP) and autofluorescence images (AF) in AMD patients with bilateral GA at baseline and 1 year of follow-up. Presence of GA was identified on FP and confirmed on corresponding AF images. Absence of neovascular AMD was confirmed using fluorescein angiography at both visits. All images were evaluated by the University of Wisconsin Fundus Photograph Reading Center. The GA area was measured using planimetry. The GA area and growth rate were compared between the eyes of each participant from FP (n=352 eyes of 176 participants) and corresponding AF (n=266 eyes of 133 participants) images. Other characteristics compared between the two eyes include foveal involvement, focality (uni or multifocal) and configuration (small, multifocal, solid, ring and horseshoe).

Results : Mean baseline GA area with FP for right eye (OD) was 9.14 mm² (±5.83) and left eye (OS) was 8.56 mm² (±5.84); with AF for OD was 10.06 mm² (±5.56) and OS was 9.82 mm² (±5.60). The mean difference of GA area between both eyes with FP was 0.58 mm² (95% confidence limits (95%CL) -8.67, 9.83, p=0.1064) and AF was 0.18 mm² (95% CL -8.58, 8.94, p=0.6387). Agreement in baseline area within 1 mm² between the two eyes was seen in 25% with FP and 19.3% with AF. Mean GA growth rate with FP for OD was 1.69 mm²/Yr (±1.67) and OS was 1.67 mm²/Yr (±1.81); and with AF for OD was 1.65 mm²/Yr (±1.48) and OS was 1.63 mm²/Yr (±1.62). The mean difference of GA growth rate between both eyes with FP was 0.02 mm²/Yr (CL: -3.68 to 3.67, p=0.8848) and AF was 0.01 mm²/Yr (CL -2.30 to 2.32, p=0.9451). The agreement between both eyes for foveal involvement, focality and configuration with FP/AF showed 73%/71%, 78%/80% and 47%/54%, respectively.

Conclusions : There is a high degree of concordance between the two eyes among participants with bilateral GA in terms of growth rate, center involvement and focality, despite a variability in the baseline GA area. Furthermore, about half the participants in this dataset had identical GA configuration between the two eyes. Our results could be helpful in designing clinical trials for potential GA treatment.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.

 

An example of GA presence and enlargement in bilateral GA