Optical Quality and Vision After Descemet’s Stripping With Endothelial Keratoplasty, and in Healthy Pseudophakic Eyes and Phakic Eyes

Abstract

Purpose: : To compare the optical quality and vision of pseudophakic eyes after Descemet’s stripping with endothelial keratoplasty (DSEK) to the optical quality of otherwise healthy pseudophakic eyes and normal eyes.

Methods: : Seventy-four eyes of 47 subjects, including 13 pseudophakic eyes at 6 months after DSEK (with the donor prepared by a microkeratome), 27 pseudophakic but otherwise healthy eyes, and 34 normal eyes, were examined with the OQAS^TM (Optical Quality Analysis System, Visiometrics, Terrassa, Spain), which objectively determines the retinal point-spread function by using a double-pass of the ocular media. Optical quality was assessed by measuring the Strehl ratio, which is higher in eyes with better optical quality, and the objective scatter index (OSI), an objective variable calculated from the brightness of the point-spread function in a defined band from the center and presumed to indicate forward scatter. Low-contrast visual acuity (LCVA) was measured as the logarithm of the minimum angle of resolution (logMAR) by using a 10% contrast ETDRS chart. Variables were compared between groups by using generalized estimating equation models, which account for possible correlation between fellow eyes of the same subject

Results: : The Strehl ratio was lower after DSEK (0.08 ± 0.02, mean ± standard deviation) than in pseudophakic eyes (0.13 ± 0.04, p<0.001), and lower in pseudophakic eyes than in normal eyes (0.19 ± 0.06, p<0.001). The OSI was higher after DSEK (5.72 ± 2.73) than in pseudophakic eyes (2.07 ± 1.16 p<0.001), and higher in pseudophakic eyes than in normal eyes (0.84 ± 0.97, p<0.001). LCVA was worse after DSEK (0.59 ± 0.21 logMAR) than in pseudophakic eyes (0.34 ± 0.23 logMAR, p=0.01), and worse in pseudophakic eyes than in normal eyes (0.15 ± 0.10 logMAR, p<0.001). For all eyes, LCVA correlated with the Strehl ratio (r= -0.55, p<0.001, n=74) and with the OSI (r=0.65, p<0.001, n=74).

Conclusions: : Optical quality is worse in pseudophakic eyes after DSEK than it is in otherwise healthy pseudophakic eyes, and is associated with worse LCVA. The differences in optical quality and visual acuity between these two groups of patients can be attributed to optical properties of the cornea after DSEK.

Keywords: transplantation • optical properties • visual acuity