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Praveen J. Patel, Fred K. Chen, Gary S. Rubin, Adnan Tufail; Intersession Repeatability of Contrast Sensitivity Scores in Age-Related Macular Degeneration. Invest. Ophthalmol. Vis. Sci. 2009;50(6):2621-2625. doi: 10.1167/iovs.08-2407.
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purpose. To describe the intersession repeatability of contrast sensitivity (CS) measurement using Pelli-Robson charts in patients with age-related macular degeneration.
methods. Repeatability was calculated from three measurements of CS over a 12-week period using a standardized protocol in 107 nontreated eyes of 107 patients with age-related macular degeneration who were enrolled in an ongoing clinical trial.
results. Data from 91 patients were included in the analysis, with a 95% coefficient of repeatability of 7 letters (0.35 log CS), ranging from 6 letters for 32 eyes with drusen only to 8 letters for patients with late AMD (macular scars or geographic atrophy). Three (3%) of these stable patients had an apparent six or more letter reduction in contrast sensitivity at the week 1 visit compared with baseline.
conclusions. There is a high intersession test–retest variability of Pelli-Robson CS scores in patients with AMD, with implications for AMD clinical trial design. Although a change criterion of six or more letters may be an adequate end point in clinical trials for patients with early AMD, a larger change criterion may be necessary for clinical trials of patients with late AMD.
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