Geographic Atrophy on Fundus Autofluorescence and Color Fundus Photographs: Association with Deep Visual Sensitivity...

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.

Reader study.

One hundred seventy-one pairs of CFP and FAF images from 60 eyes of 53 individuals.

High-density, targeted microperimetry testing (with Goldmann Size III stimuli) was performed twice per visit in a 3.5° (approximately 1000 μm) diameter region of interest with retinal pigment epithelium and outer retinal atrophy on OCT imaging. Twelve readers from 6 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. Geographic atrophy on CFP was defined as a well-demarcated, roughly round or oval region of hypopigmentation, 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.

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 nonresponding test location on microperimetry).

Color fundus photograph-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 ≥675 μm had a ≥90% prevalence of a repeatable ≤10 dB defect.

Color fundus photograph and FAF-defined GA lesions ≥175 μm do not show the same functional characteristics as regions with a truly nonresponding 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.

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