Purpose:
To determine the topographic distribution of geographic atrophy (GA) patches in patients with advanced dry age-related macular degeneration (AMD)
Methods:
Confocal scanning laser ophthalmoscopy fundus autofluorescence images (FAF, exc = 488, em 500 - 700 nm) from 348 right eyes of 348 patients from the Geographic Atrophy Progression (GAP)-Study were retrospectively analyzed. Using a modified Early Treatment Diabetic Retinopathy Study (ETDRS) grid to divide the posterior pole into 10 different sectors, the localization of atrophic patches for each sector was determined at baseline. Quantification of GA areas was performed by semi-automated image analysis software.
Results:
The mean total size of GA area was 7.29 mm2 (range 1.25 to 17.48). Clear foveal sparing was present in 119 eyes (34%), while subfoveal lesions were seen in 70 eyes (20%). In 159 eyes (46%), the involvement of the fovea was not gradable with certainty. Sector analysis showed atrophy involvement within 500 microns from the foveal center to be present in 96% of all eyes. The parafoveal macula (circle of 3000 microns centered on the fovea) showed GA more frequently (98%) when compared to more eccentric areas (circle of 6000 microns; 63%). In 32 (9%) eyes, atrophy was found beyond 6000 microns from the foveal center. Both in the sectors from the middle circle and the outer circle, atrophy was recorded more frequently in the temporal (97% and 64%) as opposed to the nasal macula (91% and 60%). Superior involvement from the foveal center (95% and 63%) was similar compared to inferior involvement (98% and 62%).
Conclusions:
The results indicate an eccentricity-dependent development and an asymmetric topographic distribution of GA in relation to the foveal center. The RPE and outer neurosensory retina temporal to the center appears more susceptible than the nasal area for occurrence and expansion of GA. Refined analyses of topographic distribution and directional spread of GA is important both for the understanding of the natural history of the disease as well as for the design and outcome measures for interventional clinical trials.
Clinical Trial:
http://www.clinicaltrials.gov NCT00599846
Keywords: age-related macular degeneration • clinical (human) or epidemiologic studies: prevalence/incidence • imaging/image analysis: clinical