December 2002
Volume 43, Issue 13
ARVO Annual Meeting Abstract  |   December 2002
Corneal Topographic Convextiy Mapping for Keratoconus Screening
Author Affiliations & Notes
  • D Huang
    Cole Eye Institute Cleveland Clinic Foundation Cleveland OH
  • M Tang
    Biomedical Engineering Ohio State University Columbus OH
  • Footnotes
    Commercial Relationships   D. Huang, None; M. Tang, None. Grant Identification: Whitaker Foundation grant RG 99-0302
Investigative Ophthalmology & Visual Science December 2002, Vol.43, 155. doi:
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      D Huang, M Tang; Corneal Topographic Convextiy Mapping for Keratoconus Screening . Invest. Ophthalmol. Vis. Sci. 2002;43(13):155.

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

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Abstract: : Purpose: Keratoconus is a frequent contraindication for corneal refractive surgery. Corneal topography is routinely performed to rule out keratoconus and forme fruste keratoconus before surgery. Diagnosis of keratoconus on the widely used axial map is complicated because cone appearance is heavily influence by location and coexisting astigmatism. The purpose of this study is to develop a new type of corneal topographic map that improves cone detection. Methods: We map the convexity of the cornea by applying the Laplacian operator on corneal height. The convexity map is computed for simulated normal, astigmatic, and variants of keratoconic topographies. Diagnostic screening using convexity map and indices are tested in 12 keratoconus eyes and 12 normal eyes. The axial power-based Rabinowitz indices are used for comparison. Results: The convexity map shows the same cone appearance regardless of location on the cornea or coexisting astigmatism. Both convexity indices and the combined Robinowitz index (KISA) have 100% sensitivity and specificity. Conclusion: Convexity indices performs as well as Rabinowitz indices in this small sample. Keratoconus pattern is simple and easy to recognize on convexity maps. The theoretical advantages of convexity mapping in keratoconus screening need to be explored in larger trials.

Keywords: 450 keratoconus • 599 topography 

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