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A. S. Lindblad, P. Lloyd, G. Gensler, T. Clemons, F. L. Ferris, III, Age-Related Eye Disease Study Research Group; Progression of Geographic Atrophy as Measured by Digital Area; Results From the Age-Related Eye Disease Study (AREDS). Invest. Ophthalmol. Vis. Sci. 2007;48(13):2162.
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To evaluate digital measurement of geographic atrophy (GA) area as an outcome for the study of age-related macular degeneration.
112 participants (140 eyes) with at least 0.5 disc areas of GA at the baseline visit of the Age-Related Eye Disease Study were evaluated. All available fundus photographs from the baseline visit and each follow-up visit were digitized and then graded for area of GA. Eleven participants with bilateral GA were graded independently by two reading centers and the results compared. Sixty-seven participants with at least 6 years of follow-up were stratified by quartile of baseline area of atrophy and median change in growth was calculated. Twenty-two participants included in this cohort had bilateral GA. The correlation between the eyes for change in area was calculated for this subset.
A comparison of the digital area grades from the two reading centers found high correlation (0.98 OD and 0.95 OS) between the centers with a mean difference in grades of 0.13 and 0.11 mm2 OD and OS respectively. Linear growth of digital area over annual visits was observed in each of the first three quartiles with a potential ceiling effect observed for the 4th quartile. For right eyes and left eyes combined, in the first quartile (median baseline: DA=0.66 and digital area=1.66 mm2) the change in digital area by 6 years was 3.14 mm2; for quartile 2 (median baseline: DA=1.17 and digital area=2.96 mm2) it was 9.67 mm2; for quartile 3 (median baseline: DA=2.25 and digital area=5.71 mm2) it was 11.96 mm2; and for quartile 4 (median baseline: DA=4.19 and digital area=10.67 mm2) it was 18.77 mm2. The correlation between eyes of change in area in 22 participants with bilateral GA was 0.89 over all follow-up visits.
Digital grading of geographic atrophy appears to be a reproducible method of evaluating morphologic progression. A strong correlation between eyes of change in area was observed for eyes presenting with bilateral disease.
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