Keratometric measurements and IOL calculations in pseudophakic post-DSAEK patients

BACKGROUND: To compare different K readings in pseudophakic patients post-Descemet’s stripping automated endothelial keratoplasty (DSAEK) and evaluate corresponding prediction errors in intraocular lens (IOL) power calculations. METHODS: Subjects that underwent cataract surgery and DSAEK surgery at least 3 and 6 months prior, respectively, and IOL implantation in the capsular bag were included in this study. Manifest refraction and IOL information were recorded. A Scheimpflug keratometer (Pentacam) was used for corneal measurements, including the mean anterior and posterior radii of curvature, simulated keratometer (SimK), true net power (TNP), and equivalent K reading (EKR) at the 4.0-mm zone. Conventional keratometry was acquired using the IOLMaster (K(Master)). The four K measurements were evaluated for calculating the predicted refraction. RESULTS: The study included 20 eyes from 19 subjects. The ratio of the posterior to the anterior corneal radius was 74.1 ± 3.24%. Comparison of the four keratometric methods (K(Master), SimK, EKR, and TNP) revealed statistically significant differences among all the methods besides K(Master) and SimK. Of the four IOL calculation methods(K(Master), SimK, EKR and TNP method),the arithmetic prediction error of the K(Master), SimK, and EKR methods featured nonsignificant differences from zero(p = 0.07, 0.19 and 0.84 respectively); the EKR method calculated the highest percentage of eyes with IOLs within the prediction error. CONCLUSIONS: IOL calculations in post-DSAEK eyes using K(Master), SimK, and EKR can yield small refractive errors after surgery. The EKR (4.0-mm diameter) method was found to be the most accurate.