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CA Applegate, JS Sunness, DA Perry; Contrast Sensitivity in Patients with Geographic Atrophy from AMD . Invest. Ophthalmol. Vis. Sci. 2002;43(13):1231.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To study the long-term natural history of contrast sensitivity in eyes with geographic atrophy (GA) from AMD. Methods: A prospective natural history study enrolled 157 subjects with GA in one or both eyes. The average age at baseline was 78. Ninety five subjects had bilateral GA and no CNV, 45 had GA without CNV in the study eye and CNV in the fellow eye, 15 had GA in the study eye and drusen in the fellow eye, and 2 subjects had fellow eyes that could not be evaluated. Annual follow-up data is available for 112 at one year, 100 at two, 87 at three, 76 at four, and for 63 subjects at five years. At each visit, best-corrected ETDRS visual acuity and Pelli-Robson contrast sensitivity were measured after a protocol refraction. Kaplan-Meier survival analysis was performed to determine the rate of contrast sensitivity loss. Results: Pelli-Robson contrast sensitivity (expressed here as log contrast sensitivity, and called PCS) is reduced from the elderly normal of 1.65 at all stages of geographic atrophy, with a median baseline PCS of 1.08. There was no significant difference in PCS between subjects with visual acuity (VA) better than 20/50 (median PCS 1.20) and those with VA of 20/50 or worse but better than 20/200 (median PCS 1.15), while those subjects with VA of 20/200 or worse had more reduced contrast sensitivity (median PCS 0.7). Over the course of the prospective study, PCS worsened over time. A six letter loss (doubling of the contrast, 0.3 log unit loss) from baseline was seen in 11% of subjects by one year, 23% by two, 33% by three, 43% by four, and 66% by five years for all subjects, with similar rates across visual acuities better than 20/200. A twelve letter loss (quadrupling of the contrast, 0.6 log unit loss) was seen in 8% of subjects by year five. The level of contrast sensitivity at baseline does not help to predict the rate of visual acuity loss by 2 years within each visual acuity group. Conclusion: Loss of contrast sensitivity adds to the visual impairment associated with decreased visual acuity and presence of scotomas in the central visual field in subjects with geographic atrophy from AMD.
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