July 2018
Volume 59, Issue 9
Open Access
ARVO Annual Meeting Abstract  |   July 2018
Identifying Optimal Scheimpflug Parameters to Predict Ectasia Risk after LASIK
Author Affiliations & Notes
  • James Bradley Randleman
    Ophthalmology, USC Roski Eye Institute, Los Angeles, California, United States
  • Eric Hwang
    Ophthalmology, USC Roski Eye Institute, Los Angeles, California, United States
  • Julie M. Schallhorn
    Ophthalmology, UCSF, San Francisco, California, United States
  • Footnotes
    Commercial Relationships   James Randleman, None; Eric Hwang, None; Julie Schallhorn, None
  • Footnotes
    Support  Supported by an unrestricted grant from Research to Prevent Blindness to the University of Southern California Roski Eye Institute and the University of California San Francisco Department of Ophthalmology
Investigative Ophthalmology & Visual Science July 2018, Vol.59, 5774. doi:
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    • Get Citation

      James Bradley Randleman, Eric Hwang, Julie M. Schallhorn; Identifying Optimal Scheimpflug Parameters to Predict Ectasia Risk after LASIK. Invest. Ophthalmol. Vis. Sci. 2018;59(9):5774.

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

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Abstract

Purpose : To evaluate Scheimpflug parameters in distinguishing eyes that developed ectasia after LASIK from eyes with uneventful follow-up after LASIK

Methods : Measurements from 33 eyes of 33 patients who developed ectasia after LASIK and 925 eyes of 925 patients with at least 2 years of uneventful follow-up after LASIK were evaluated with the Pentacam HR (Oculus, Inc.), including anterior curvature metrics, astigmatism, pachymetry, and keratoconus screening indices (30 variables). Results were adjusted with a Bonferroni correction and statistically significant variables were evaluated with receiver operating characteristic (ROC) curves.

Results : The following measurements were statistically significant between groups (p<0.001): astigmatism, pachymetry values (apex, pupil, minimum, min y), index of surface variance (ISV), index of vertical asymmetry (IVA), keratoconus index (KI), central keratoconus index (CKI), index of height decentration (IHD) and Inferior Superior-Value (IS-Value) (p-value <.001). Eyes that developed ectasia had thinner corneas and higher screening values across all variables compared to control eyes. Highest AUC values were found for IS-value (0.750), KI (0.745) and PachyMin (0.709 ). No other metric achieved an AUC >0.7.

Conclusions : Eyes that developed ectasia post-LASIK had significantly greater surface asymmetry and thinner corneas compared to control eyes. While IS-value and KI were best, no individual Scheimpflug metric distinguished the two populations well.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.

 

Example topometric map from a patient who developed ectasia after LASIK

Example topometric map from a patient who developed ectasia after LASIK

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