Graft Thickness, Graft Folds, and Aberrations After Descemet Stripping Endothelial Keratoplasty for Fuchs Dystrophy

Abstract

Purpose To determine whole eye high-order aberrations (HOAs) in pseudophakic eyes after Descemet stripping endothelial keratoplasty (DSEK) for Fuchs dystrophy, and to establish relationships between graft thickness, HOAs, and visual acuity. Design Cross-sectional study. Methods Whole eye HOAs were measured in pseudophakic eyes at intervals through 24 months after DSEK, and in otherwise healthy pseudophakic control eyes implanted with the same type of spherical intraocular lens. Wavefront errors were assessed by a Hartmann-Shack aberrometer over a 4 mm-diameter optical zone. In DSEK eyes, central graft thickness and stromal graft folds were measured by using confocal microscopy in vivo, and best-corrected visual acuity (BCVA) was determined by the electronic Early Treatment of Diabetic Retinopathy Study method. Results Total HOAs at 24 months after DSEK (0.28 ± 0.11 μm, mean ± SD, n=17) were higher than those in pseudophakic controls (0.16 ± 0.07 μm, n=25, p<0.001); specifically, trefoil and quadrafoil were higher after DSEK. At 24 months, total HOAs (r= 0.69, p<0.001) and graft folds (r= 0.41, p= 0.02) were correlated with central graft thickness, and BCVA was correlated with total HOAs (r= 0.39, p=0.01) but not with graft thickness (r= −0.24, p= 0.20, n=27). Conclusions Whole eye HOAs are higher after DSEK compared to untreated corneas. Thicker grafts are associated with increased HOAs and more graft folds, suggesting that the donor lenticule contributes, in part, to the wavefront errors. Although BCVA is weakly related to total HOAs after DSEK, it is not related to graft thickness.

Determinants of visual quality after endothelial keratoplasty

“…67,95,112 Chamberlain et al found that anterior corneal HOAs were higher after DSAEK than in age-matched controls, showing that the underlying disease process and / or the surgical technique (i.e. corneal incisions) have a tangible effect on the anterior cornea.…”

“…36,71 Graft folds affect the posterior corneal surface, and are believed to be due to a mismatch in curvature between the host stroma and anterior graft surface. 112 Letko et al reported uneven graft thickness and graft folds in the visual axis of the donor graft in cases of unsatisfactory visual acuity after DSAEK. 71 Seery et al found that thicker grafts were associated with more graft folds, which in turn correlated moderately and significantly with HOAs at 24 months (r=0.44).…”

“…Theories include a more regular posterior graft surface with greater thickness uniformity , 31,77,112 thinner grafts with a better match in curvature, and improved parallelism between the graft and recipient and improved optical compensation by the posterior cornea. 139 Posterior corneal HOAs are increased after all forms of EK compared with normal controls, 21,54,84,108,137 and posterior corneal HOAs after DSAEK seem to be comparable to or greater than post-PKP.…”

“…112 McLaren and Patel studied induced forward light scatter and wholeeye HOAs in healthy eyes. 77 They induced light scatter greater than would be expected after DSEK, but found only a minimal effect on BCVA.…”

Combined Use of a Femtosecond Laser and a Microkeratome in Obtaining Thin Grafts for Descemet Stripping Automated Endothelial Keratoplasty: An Eye Bank Study

“…The influence of endothelial graft thickness on visual acuity in DSAEK is controversial, with some authors reporting better results with thinner grafts and others finding no correlation (10)(11)(12)(13)(14)(15). However, studies evaluating this subject have either focused on relatively thick grafts (160-170 µm) or on grafts prepared by manual dissection (11)(12)(13)(14)(15). When grafts having less than 130 µm are evaluated, a positive correlation between thickness and visual acuity is obtained (9,10), suggesting that an effect may exist under a certain thickness.…”