Association between corneal edema and corneal astigmatism after Descemet membrane endothelial keratoplasty

To evaluate changes in corneal astigmatism after DMEK and determine the predictive value of preoperative central corneal thickness (CCT) for postoperative astigmatic change.

Fifty-five eyes with Fuchs' endothelial dystrophy (FED) or pseudophakic bullous keratopathy (PBK) undergoing DMEK were analyzed. Auto kerato-refractometer (ARKRT)-derived anterior corneal astigmatic change was defined as the primary outcome in 55 eyes. Anterior-segment optical coherence tomography (AS-OCT)-derived anterior, posterior, and total corneal parameters were analyzed as secondary outcomes in 25 eyes. Vector analysis assessed magnitude and axis changes. Associations between preoperative CCT and postoperative astigmatic change were evaluated; an exploratory ROC analysis was performed for astigmatic change.

Mean preoperative CCT was 738.7 ± 99.7 μm, decreasing to 517.5 ± 37.3 μm postoperatively (P < 0.001). Anterior astigmatism measured by ARKRT decreased significantly after DMEK, whereas anterior and total corneal astigmatism measured by AS-OCT showed a similar decreasing trend without statistical significance. Greater preoperative CCT showed a larger postoperative astigmatic change on ARKRT. In ROC analysis based on ARKRT measurements, a preoperative CCT of 790 μm showed modest discrimination for postoperative astigmatic change > 3.0 D (AUC = 0.749; sensitivity 67%, specificity 81%). PBK eyes showed greater anterior flattening and larger reductions in absolute astigmatism than FED eyes.

Preoperative corneal edema is associated with postoperative astigmatic change after DMEK. The 790 μm CCT cutoff showed modest discrimination. In eyes with marked edema, staged astigmatic correction may improve refractive outcomes.