Corneal Stromal Thinning and Posterior Irregularity After DMEK: Clinical Observations and Biophysical Hypotheses.

PURPOSE: The aim of this study was to identify factors associated with significant postoperative stromal thinning in eyes undergoing Descemet membrane endothelial keratoplasty (DMEK).

METHODS

This was a retrospective, multicenter interventional study. Eyes that underwent DMEK at Royal Liverpool University Hospital (UK) and ASST Spedali Civili di Brescia (Italy) were included. Eyes were stratified into 2 groups based on the final central corneal thickness (CCT): <500 μm and ≥500 μm. Demographic, clinical, and tomographic parameters were analyzed, including age, preoperative CCT, best corrected visual acuity (BCVA), posterior and total corneal power, and donor endothelial cell density (ECD). Hyperopic shift was defined as an increase of ≥+0.5 D in posterior corneal power or a decrease of ≤-1.0 D in total corneal power.

RESULTS

Among 150 eyes (120 patients), those with a final CCT <500 μm were significantly older (mean [SD], 74.5 [9.9] vs. 68.7 [11.5] years; P = 0.001). Hyperopic shift occurred in 43% of eyes with complete tomographic data and correlated with a greater percentage reduction in CCT after DMEK (-25.5% [15.6%] vs. -16.4% [12.4%], P = 0.02). A larger proportional CCT reduction was observed in eyes with a final CCT <500 μm and was associated with the presence of preoperative posterior stromal ripples. No significant differences were observed in final BCVA, donor ECD, or treatment center.

CONCLUSIONS

Greater reductions in corneal thickness are associated with postoperative stromal thinning and hyperopic shift after DMEK. Preoperative stromal ripples are associated with greater reductions in corneal thickness after DMEK. Stromal remodeling appears influenced by endothelial recovery and preoperative biomechanical status, supporting emerging hypotheses on keratocyte loss and osmotic imbalance.