Using the posterior to anterior corneal curvature radii ratio to minimize the risk of a postoperative hyperopic shift after Descemet membrane endothelial keratoplasty

Purpose To evaluate different corneal parameters in identifying patients at risk of a hyperopic shift after (DMEK). Methods This retrospective study included 92 eyes of patients with FECD after DMEK surgery. Pachymetry parameters, various tomographic parameters and densitometry values before and after DMEK were determined using a rotating Scheimpflug system (Pentacam HR, Oculus). For assessing the posterior to anterior corneal curvature relationship, we calculated the R-PA (posterior to anterior corneal curvature radii ratio). Results The average keratometry reading of the posterior corneal surface (Km(B)) increased and the total corneal refractive power (TCRP) decreased significantly after surgery (P < .001). There was a significant difference between the preoperative and postoperative R-PA (P < .001) and the posterior Q value (P < .001). The strongest correlation was found between the change in the Km(B) and the preoperative R-PA (Spearman's correlation coefficient = 0.872, P < .001). In the receiver operating characteristic (ROC) analysis, the highest AUC values (for increment Km(B)) among the different preoperative parameters tested were obtained for R-PA and posterior Q value (Asph. Q(B)) with AUROC (area under the ROC) values of 0.95 and 0.89, respectively. Conclusions The Q value and the R-PA showed the highest correlation with the change in corneal refractive power and the greatest AUC. These parameters could be used as surrogate markers to identify eyes that might be at risk of a greater postoperative hyperopic shift, which would allow more accurate setting of refractive goals.