ABSTRACTPurpose To determine the functional characteristics of color fundus photograph (CFP)- and fundus autofluorescence (FAF)-defined geographic atrophy (GA) lesions by evaluating the prevalence of repeatable deep visual sensitivity defects. Design Reader study. Participants One hundred seventy-one pairs of CFP and FAF images from 60 eyes of 53 individuals. Methods High-density, targeted microperimetry testing (with Goldmann Size III stimuli) was performed twice per visit in a 3.5° (approximately 1,000 μm) diameter region-of-interest with retinal pigment epithelium and outer retinal atrophy (RORA) on OCT imaging. Twelve readers from six established reading centers assessed CFP and FAF images within these regions sampled on microperimetry for GA, and performed annotations where GA was deemed to be present. GA on CFP was defined as a well-demarcated, roughly round or oval region of hypopigmentation, and separately with and without requiring increased visibility of the underlying choroidal vessels (referred to as CFP-defined GA1 and GA2 respectively). GA on FAF was defined as a region of definite decreased autofluorescence. Main Outcome Measures Prevalence of a repeatable ≤10 dB defect for CFP- and FAF-defined GA ≥175 μm, and the minimum lesion size showing a ≥90% prevalence of a repeatable ≤10 dB defect (deemed characteristic of regions with a truly non-responding test location on microperimetry). Results CFP-defined GA1 and GA2, and FAF-defined GA, ≥175 μm were graded as present in 13%, 31% and 41% of images respectively, and 77%, 67% and 62% lesions respectively had a repeatable ≤10 dB defect. Only CFP-defined GA1 ≥625 μm, CFP-defined GA2 ≥650 μm, and FAF-defined ≥675μm had a ≥90% prevalence of a repeatable ≤10 dB defect. Conclusions CFP- and FAF-defined GA lesions ≥175 μm do not show the same functional characteristics as regions with a truly non-responding test location, and only much larger lesions (approximately ≥650 μm) showed such similar functional characteristics. These findings provide crucial insights when considering CFP- and FAF-defined atrophic endpoints for clinical studies.
Gee et al. (Mon,) studied this question.