December 2002
Volume 43, Issue 13
ARVO Annual Meeting Abstract  |   December 2002
The Relation Between Visual Acuity and Topographic Indices in Keratoconus
Author Affiliations & Notes
  • TT McMahon
    Ophthalmology Univ of Illinois Chicago Chicago IL
  • RJ Anderson
    Epidemiology and Biostatistics University of Illinois at Chicago/School of Public Health Chicago IL
  • LB Szczotka
    Ophthalmology University Hospitals of Cleveland/Case Western Reserve University Cleveland OH
  • C Roberts
    The Ohio State University Columbus OH
  • A Mahmoud
    The Ohio State University Columbus OH
  • NE Friedman
    University of California School of Opometry Berkeley CA
  • LJ Davis
    University of Missouri-St Louis School of Optometry St Louis MO
  • TW RaaschCLEK Study Group
    The Ohio State University College of Optometry Columbus OH
  • Footnotes
    Commercial Relationships   T.T. McMahon, None; R.J. Anderson, None; L.B. Szczotka, None; C. Roberts, None; A. Mahmoud, None; N.E. Friedman, None; L.J. Davis, None; T.W. Raasch, None. Grant Identification: Support NIH Grant EY12656
Investigative Ophthalmology & Visual Science December 2002, Vol.43, 142. doi:
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    • Get Citation

      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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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract: : 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  

Keywords: 450 keratoconus 

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