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TT McMahon, RJ Anderson, LB Szczotka, C Roberts, A Mahmoud, NE Friedman, LJ Davis, TW RaaschCLEK Study Group; The Relation Between Visual Acuity and Topographic Indices in Keratoconus . Invest. Ophthalmol. Vis. Sci. 2002;43(13):142.
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Purpose:To describe corneal topographic correlates to measures of visual acuity in keratoconus subjects. Methods:Two Keratron topography maps from 733 randomly selected non-grafted right or left eyes of Collaborative Longitudinal Evaluation of Keratoconus (CLEK) Study subjects were averaged and analyzed using simulations of published topographic indices. Indices were put into four groupings, "Curvature" (SKVAL, SimkS, SimkF, ACP, BFS, MAG), "Asymmetry" (SAI, DSI, OSI, ISVAL, CSI), "Irregularity" (TI, SRI, IAI, SDP), and "Regular astigmatism" (CYL, BFC). Clinical measures studied were best-corrected high (BCAH) and low (BCAL) contrast acuity, and manifest refraction acuity (MRHC). Results:The table demonstrates curvature, asymmetry, irregularity and astigmatism were individually associated with each of the visual acuity measures (p<.001). Partial F-tests demonstrate that asymmetry, regularity, and curvature were highly statistically significant (p<.0001) when regular corneal astigmatism was partialled out, indicating that astigmatism does not explain much of the variability in acuity. Conclusion:The results suggest that corneal curvature, asymmetry, and corneal irregularity had the strongest power in explaining visual acuities under both manifest refraction and best-corrected (rigid contact lens) conditions. Support: NIH Grants EY12656, EY10419, EY10069, EY 10077, NEI Core Grant EY1792 (UIC), and an unrestricted grant from Research to Prevent Blindness. R-Square values View OriginalDownload SlideView OriginalDownload Slide
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