Changes in Corneal Refractive Power for Patients With Fuchs Endothelial Dystrophy After DMEK

PURPOSE:To quantify changes in the refractive power of the anterior and posterior corneal surfaces after Descemet membrane endothelial keratoplasty (DMEK) so as to optimize the accuracy of intraocular lens (IOL) power calculations. METHODS:This study included 28 eyes of 21 patients (age 66.6 ± 9.4 years, 11 female, 10 male). Scheimpflug-based Oculus Pentacam imaging was performed before and after DMEK surgery for Fuchs endothelial dystrophy. Corneal power was measured using the K-value of simulated keratometry (SimK) of Pentacam and total corneal refractive power (TCRP) in corneal zones from 1 to 8 mm (SimK 1-8, TCRP1-8). We also analyzed changes in the keratometric power deviation (KPD) and pachymetry. RESULTS:Changes in the SimK in the central cornea were minimal and not significant (SimK 3before = 43.24 ± 1.33 D; after = 43.01 ± 1.37 D; P = 0.101) but they decreased significantly in the corneal periphery (SimK 4P = 0.021; SimK 5P = 0.004; SimK 6P = 0.002; SimK 7P = 0.002; SimK 8P = 0.008). Postoperative TCRP in the central cornea decreased significantly compared with preoperative values (TCRP 3before = 43.05 ± 1.44 D; after = 41.94 ± 1.34 D; P < 0.001); [TCRP 4before = 43.16 ± 1.40 (D); after = 41.99 ± 1.27 (D); P < 0.001]. The keratometric power deviation increased significantly after DMEK (before = 0.74 ± 0.45 D; after = 1.40 ± 0.26 D; P < 0.001). CONCLUSIONS:DMEK surgery induced a significant change in the refractive power of the posterior surface of the cornea and thus a decrease in the TCRP of about 1 D, whereas the SimK, which measures only the anterior cornea, remained nearly unchanged. To avoid a hyperopic surprise, it is essential that this TCRP decrease is not overlooked in intraocular lens power calculations.