Progression Of Primary Geographic Atrophy (GA) In Areas Of Reticular Macular Disease (RMD) In Age-related Macular Degeneration (AMD)

Abstract

Purpose: : To examine the progression of primary GA and its relation to RMD using autofluorescence (AF) and infrared (IR) images.

Methods: : We retrospectively identified 30 subjects (42 eyes) with a diagnosis of primary GA who had >=2 examinations with AF or IR imaging and were followed for >= 6 months, excluding patients with GA secondary to neovascularizaton or other retinal diseases. We classified baseline GA into three patterns: unilobular, multilobular, and merged-multilobular¹. We calculated areas of GA and progression rates using custom interactive software² and recorded the initial location of GA (extrafoveal vs foveal), the presence of peripapillary atrophy, and the presence of RMD³.

Results: : The mean duration of follow up was 26.1 months (range 6 - 51 months). At baseline, 4 eyes (9.5%) had unilobular GA, 32 eyes (76.2%) had multilobular GA, and 6 eyes (14.3%) had merged-multilobular GA. The mean GA size at baseline was 3.16 mm². The mean GA growth rate was 1.13 mm²/yr overall and was statistically significantly different between the unilobular (0.32 mm²/yr) and multilobular groups (1.16 mm²/yr, p<0.001), but not between the multilobular and merged-multilobular groups (1.53 mm²/yr). With respect to initial GA size, the lower 50th percentile had a lower progression rate than the upper 50th percentile (0.96 mm²/yr vs 1.41 mm²/yr, p=0.031). Age and gender did not influence GA progression.Among all eyes, 33 (78.6%) had peripapillary atrophy and 29 (69%) had extrafoveal GA at baseline. 4 eyes (9.52%) progressed from extrafoveal to foveal GA, 3 of which belonged to the multilobular group. Among eyes with multilobular GA, 71.4% progressed to merged-multilobular. 100% of eyes had RMD, and 40 eyes (95.2%) showed GA progressing in areas previously involved by RMD.

Conclusions: : Serial imaging suggests that the progression rate of primary GA is influenced by the initial lesion size and pattern. Eyes with the highest progression rates were those with the largest initial lesions and the multilobular or merged-multilobular pattern. The nearly universal occurrence of RMD with primary GA and the frequent observation of lobules of GA developing in areas of RMD suggest progression of a single underlying disease process. 1. Klein et al.(2008)AJO;146:692-9.2. Lee et al.(2008) IEEE Conf Proc Signal Process; pp 655-58.3. Smith et al.(2009)AJO;148:733-43.

Keywords: age-related macular degeneration • clinical (human) or epidemiologic studies: natural history • image processing