Abstract
Purpose:To evaluate and modify the Randleman Ectasia Risk Score System for predicting post-laser in situ keratomileusis (LASIK) ectasia in patients with normal preoperative corneal topography.Methods:In this retrospective study we reviewed data from 136 eyes which had undergone LASIK including 34 ectatic and 102 normal eyes between 1999 and 2009. After determining the sensitivity and specificity of the Randleman system, a modified model was designed to predict the risk of post-LASIK corneal ectasia more accurately. Next, the sensitivity and specificity of this modified scoring system was determined and compared to that of the original scoring system.Results:In our sample, the sensitivity and specificity of the Randleman system was 70.1% and 50.5%, respectively. Our modified model included the following parameters: preoperative central corneal thickness, manifest refraction spherical equivalent, and maximum keratometry, as well as the number of months elapsed from surgery. Sensitivity and specificity rates of the modified system were 74.2% and 76.2%, respectively. The difference in receiver operating characteristic curves between the Randleman and modified scoring systems was statistically significant (P<0.001). The best sensitivity and specificity for our model occurred with a cumulative cutoff score of 4.00; a low risk was considered if the score was ≤4.00, and high risk was defined with a score > 4.00.Conclusion:Our modified ectasia risk scoring system for patients with normal corneal topography can predict post LASIK ectasia risk with acceptable sensitivity and specificity. However, there are still unidentified risk factors for which further studies are required.
Highlights
Laser in situ keratomileusis (LASIK) is a type of refractive surgery with proven safety and efficacy;[1] it entails complications just like any other kind of surgical procedure
A rare, but serious complication is post LASIK ectasia,[2,3,4,5,6,7,8] which is characterized by progressive thinning and steepening
According to the Randleman scoring system and based on preoperative data, in the control group 50.5% and 11.9% of eyes were at low and moderate risk, respectively while 37.6% were predicted to be at high risk of developing post-LASIK ectasia
Summary
Laser in situ keratomileusis (LASIK) is a type of refractive surgery with proven safety and efficacy;[1] it entails complications just like any other kind of surgical procedure. A rare, but serious complication is post LASIK ectasia,[2,3,4,5,6,7,8] which is characterized by progressive thinning and steepening. Randleman System for Topographically Normal Corneas; Miraftab et al Several studies have been conducted to determine risk factors for corneal ectasia[3,7,9,10] and devise corneal ectasia risk predicting scoring systems.[5,7] The Randleman Ectasia Risk Score System which was introduced[5] and validated[11] in 2008 considers five parameters including corneal topographic patterns, residual stromal bed thickness (RSB), age, central corneal thickness (CCT) and manifest refraction spherical equivalent (MRSE).[5]
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