Posters

Retrospective comparison of different preoperative tools for evaluating the risk of ectasia in a series of post-LASIK ectasia

Poster Details

First Author: D.Smadja FRANCE

Co Author(s):    M. Santhiago   G. Mello   S. Srinivasan   R. Krueger     

Abstract Details

Purpose:

To compare the ability of different preoperative evaluation tools to predict the risk of ectasia to occur.

Setting:

Refractive Surgery Department, Bordeaux Hospital University, France; Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio, United States

Methods:

Six cases of post LASIK ectasia (PLE) were retrospectively reviewed. Four different evaluation tools were applied to the preoperative data of the patients in order to assess the risk of PLE and/or to detect a cornea at risk: The Randleman Ectasia Risk Score System (ERSS), 2 artificial intelligence-based Keratoconus detection programs; the Classification Tree for Suspect Cornea (CTSC) based on tomographic analysis and the Keratoconus Probability Index (KPI) based on topographic analysis, and the intended percentage of tissue ablated (PTA) by the surgery. The ability to predict the high risk of ectasia was compared between the different methods.

Results:

The mean onset of PLE occurred at 14.3 +/- 2.1 months after the surgery and the mean achieved PTA was calculated at 37,7% +/- 5.1. The CTSC performed significantly better than the other methods for identifying the risk of PLE preoperatively (p < 0.01), with 83.3% of the corneas (5/6) identified as subclinical keratoconus, whereas the KPI labeled only 33.3% (2/6) of the corneas at risk. The ERSS classified one cornea at high risk, one with moderate risk and 4 with low risk of PLE. However, the cornea with the highest percentage of tissue ablated (41.3%), was the only cornea classified as normal by the CTSC detection program, therefore, its combination with the PTA value would have helped to identify the high risk of ectasia in 100% of the cases.

Conclusions:

The Classification Tree for Suspect Cornea showed the best ability to detect ectasia-susceptible corneas. However, its combination with the ERSS and the intended percentage of tissue ablated (PTA) remains crucial to improve the ectasia risk evaluation, particularly in cases where no cornea at risk is detected. FINANCIAL INTEREST: NONE