Author Affiliations: Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida (Mr Feuer and Drs Yehoshua, Gregori, Penha, and Rosenfeld); and National Eye Institute, Bethesda (Drs Chew and Ferris), and EMMES Corporation, Rockville (Drs Clemons and Lindblad), Maryland.
The growth of geographic atrophy (GA) over 4 years in the Age-Related Eye Disease Study (AREDS) was shown to be dependent on the baseline area of GA.1 However, 3 articles have demonstrated that the square root transformation of lesion area measurements eliminates the dependence on baseline lesion size for both the test-retest variability and the growth rates.2- 4 This square root transformation strategy was applied to the AREDS data.
Feuer WJ, Yehoshua Z, Gregori G, Penha FM, Chew EY, Ferris FL, Clemons TE, Lindblad AS, Rosenfeld PJ. Square Root Transformation of Geographic Atrophy Area Measurements to Eliminate Dependence of Growth Rates on Baseline Lesion Measurements: A Reanalysis of Age-Related Eye Disease Study Report No. 26. JAMA Ophthalmol. 2013;131(1):110-111. doi:10.1001/jamaophthalmol.2013.572