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

PURPOSE: 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 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.

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 nonresponding test location on microperimetry).

RESULTS

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.

CONCLUSIONS

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.

FINANCIAL DISCLOSURES: Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.