Mediators of Visual Acuity in Descemet Membrane Endothelial Keratoplasty and Ultrathin Descemet Stripping Automated Endothelial Keratoplasty

Abstract

Purpose: The aim of this study was to investigate mediators of visual acuity in ultrathin Descemet stripping automated endothelial keratoplasty (UT-DSAEK) compared with Descemet membrane endothelial keratoplasty (DMEK). Methods: This was a prespecified secondary analysis of the Descemet Endothelial Thickness Comparison Trial, a prospective, randomized controlled trial comparing UT-DSAEK with DMEK. Subjects with Fuchs endothelial dystrophy or pseudophakic bullous keratopathy presenting to 2 academic centers were enrolled and randomized to either UT-DSAEK (n = 25 eyes) or DMEK (n = 25 eyes). Higher order aberrations (HOAs) and corneal densitometry were measured with Pentacam Scheimpflug imaging at 3, 6, 12, and 24 months. Results: The posterior corneal surface at the 6.0-mm optical zone had significantly less total HOAs (P <0.001) in the DMEK group compared with UT-DSAEK at 24 months. Anterior and posterior corneal densitometry improved from baseline to 24 months for both UT-DSAEK and DMEK, but there was no significant difference between the 2 groups. Corneal densitometry and posterior HOAs were both associated with best-corrected visual acuity (P <0.05). DMEK had 1.3 logarithm of the minimum angle of resolution better visual acuity compared with UT-DSAEK at 24 months. Approximately 64% of this effect was mediated through posterior HOAs, whereas none was mediated through anterior HOAs or densitometry. Conclusions: Decreased posterior HOAs mediate better visual acuity and account for improved vision after DMEK compared with UT-DSAEK. Corneal light scatter as measured by densitometry is similar between UT-DSAEK and DMEK, indicating that the increased thickness and stromal–stromal interface in UT-DSAEK do not significantly affect visual acuity.