Color light-emitting diode reflection topography: Validation of Equivalent K Reading for IOL power calculation in eyes with previous corneal myopic refractive surgery.

PURPOSE To compare the accuracy of the Equivalent K reading (EKR) from Color Light-Emitting Diode Corneal Topographer (Cassini, iOptics) to that of other no-history formulas for intraocular lens (IOL) power calculation in eyes with previous myopic excimer laser surgery. SETTING Centro de Oftalmologia Barraquer, Barcelona, Spain. DESIGN Retrospective case series. PATIENTS AND METHODS In 37 eyes, the refractive outcomes of the Cassini EKR entered into the Haigis formula were compared to those of the Barrett-True K, Haigis-L, Shammas-PL formulas and the Triple-S method combined with the Haigis formula. Optimized lens constants for virgin eyes were used. The mean prediction error (PE), median absolute error (MedAE) and the percentage of eyes with a PE within ±0.25 D, ±0.50 D, ±0.75 D and ±1.00 D were calculated. RESULTS The Haigis-L, Shammas-PL and Barrett True-K no-history methods produced a myopic mean PE that was significantly different from zero (p<0.01, p<0.01 and p=0.01, respectively), whereas the mean PEs of Cassini EKR and the Triple-S combined with the Haigis formula were not different from zero. Repeated measures ANOVA disclosed a significant difference among all methods (p<0.0001). The MedAE of the Cassini EKR, Barrett True-K, Haigis-L, Shammas-PL and Triple-S were, respectively, 0.34D, 0.34D, 0.49 D, 0.48 D and 0.31D (p=0.0026). CONCLUSIONS The performance of the combination of standard Haigis formula with Cassini EKR was comparable to other no-history formulas in eyes with previous myopic excimer laser surgery.