Purpose:
Improvements in visual acuity have been shown to continue for up to three years after Descemet’s Stripping Automated Endothelial Keratoplasty (DSAEK) for endothelial dysfunction, long after corneal edema has resolved. We hypothesize that this might be due in part to long-term remodeling of the anterior corneal surface.
Methods:
From our prospective data registry of corneal transplant recipients, we identified 75 eyes of 58 patients who received DSAEK for Fuchs’ corneal endothelial dystrophy or pseudophakic bullous keratopathy. These patients had no ocular comorbidities known to limit visual acuity, and had complete datasets for three years of post-operative follow-up. Best spectacle corrected visual acuity (BCVA), surface regularity index (SRI), and surface asymmetry index (SAI) were measured at pre-op, and again at the 6, 12, 24, and 36 months post-operative time points. Changes in BCVA, SRI and SAI over time were evaluated with paired samples t-tests. At each time gate, Pearson correlation analysis was performed to detect associations between BCVA and SRI/SAI. All statistics were performed with SPSS v. 19.
Results:
Mean BCVA improved at each time point, but not every interval achieved statistical significance. Mean Snellen BCVA was 20/51 at pre-op, 20/30 at 6 months (p<0.001), 20/29 at 12 months (p=0.123), 20/25 at 24 months (p<0.001), and 20/24 at 36 months (p=0.111). Mean SRI displayed a general trend towards improvement: 0.76 at pre-op, 0.48 at 6 months (p<0.001), 0.46 at 12 months (p=0.579), 0.37 at 24 months (p=0.035), and 0.39 at 36 months (p=0.738). Mean SAI also displayed a general improvement trend: 1.24 at pre-op, 0.66 at 6 months (p<0.001), 0.59 at 12 months (p=0.189), 0.51 at 24 months (p=0.066), and 0.47 at 36 months (p=0.299). BCVA displayed a weak correlation with SRI at 6 (36%, p=0.001), 12 (37%, p=0.001), and 36 months (25%, p=0.029). BCVA and SAI were only correlated at 12 months (33%, p=0.003).
Conclusions:
Improvements in anterior surface topography occur for up to two years post-op, as opposed to only during the immediate post-operative period. These topographical changes may provide a partial explanation for the observed long-term visual gains commonly seen in DSAEK recipients.