Percentage of Foveal versus Total Macular Geographic Atrophy as a Predictor of Visual Acuity in Age-related Macular Degeneration

Abstract

35Objectives: To investigate the relationship between visual acuity (VA), total area of geographic 36 atrophy (GA) and percentage of foveal GA. 37Methods: Multicenter, retrospective cross-sectional study of patients with GA due to age-related 38 macular degeneration. Demographics, VA, fundus autofluorescence (FAF) and optical coherence 39 tomography (OCT) images were collected. Using FAF images aided by OCT, foveal sparing status, 40GA pattern, total GA size, and percentage of GA covering the foveal area -area within a 1.5 mm 41 diameter circle centered on the fovea centralis -were assessed. Univariable and multiple linear 42 regression analyses were performed. 43Results: 54 eyes (mean age 78.7 ±7.7 (SD), 60.0% female) were studied. Mean VA was 0.8 ± 0.6 44 logMAR, mean total GA 8.8 ± 6.7 mm 2 and mean percentage of foveal GA was 71.5 ± 30.9%. Of all 45 assessed eyes, 48.2% (n = 26) presented with multifocal GA, and 18.5% (n = 10) had foveal sparing. 46Multiple regression analysis revealed that, controlling for age and GA pattern, the percentage of 47 foveal GA presented a statistically significant association with VA (ß = 0.41, P = 0.004). No 48 significant associations were observed with mean total GA size, while controlling for the same 49 variables (ß = 0.010, P = 0.440). 50Conclusion: Percentage of foveal GA was significantly associated with VA impairment, while the 51 same was not verified for total GA area. These findings suggest that percentage of foveal GA may 52 represent a more useful tool for assessing the impact of GA on VA. Further validation is needed in 53 larger cohorts. 54 55 56 industrialized countries. 1 Geographic Atrophy (GA) represents the late stage of dry AMD, and it is 59 characterized by the irreversible loss of macular retinal tissue, retinal pigment epithelium (RPE), and 60 choriocapillaris. 2 Although this process occurs in a slowly progressive way, it causes decreases in 61 central vision over time 3 , which rapidly accelerates when GA covers the foveal center. GA is 62 responsible for severe vision loss in approximately 20% of all patients with AMD, may affect up to 63 22% of the population in 90-year-old people 2-4 , and more than 8 million people are affected 64 worldwide 2, 4 . For not well understood reasons, atrophic macular diseases such as GA due to dry 65 AMD can spare the foveal center until late in the disease course and the so called foveal sparing has 66 been reported in about 20% of representative GA populations enrolled in clinical trials 5 . 67 68 Color fundus photography, fundus autofluorescence (FAF) and optical coherence tomography (OCT) 69 imaging can be used to identify and follow GA lesions. However, FAF is considered by most to be 70 the imaging of choice that allows for a sharp discrimination of a lesion's boundaries. This is primarily 71 because FAF provides a good visualization of the high contrast between atrophic (hypofluorescent) 72 and normal areas 4, 6 . On OCT, GA is typically characterized by the presence of thinning of the 73 hyperreflective externa...