*Correspondence, David Lockington: davidlockington@hotmail.com

Introduction DMEK is effective in surgically treating endothelial dysfunction, with visual improvement following oedema resolution. It has been our observation that postoperative DMEK corneas are often much thinner than anticipated. We wished to review our recent cases and discuss potential explanations and implications.

Methods Retrospective case-note review of 50 consecutive DMEK patients, including demographics and serial ultrasound central corneal thickness (CCT) measurements.

Results 63 eyes (33 combined phaco/DMEK; 30 DMEK alone) from 50 patients were identified (29 male, 21 female; median age 75 (34–87)). 87.3% (55/63) had Fuchs’ endothelial corneal dystrophy. Mean preoperative CCT was 680 µm (median 663 µm, range 582–934 µm), significantly reduced at 3 months postoperatively by 23.4% (520 µm; median 522 µm; 404–611 µm) and maintained by 6 months (22.6% reduction). Mean CCT was significantly lower than expected (523 µm vs 540 µm; p<0.001 (one sided t-test)), with 61.9% under 540 µm and 31.7% less than 500 µm. No association was found between 3-month CCT and donor endothelial cell count (median 2600 cells/mm² (2200–3600); p=0.29), or median donor age (71 years (49–88); p=0.22).15.9% (10/63) of eyes required topical ocular hypotensives at 6 months.

Conclusion Approximately one-third of our cases resulted in sub-500 µm corneal thickness following DMEK. This phenomenon is not explainable solely due to a normalisation of anatomy (new functioning Descemet’s membrane/endothelial pump, corneal dehydration and epithelial re-modelling), but likely related to stromal atrophy and keratocyte death. While further research is required to confirm these findings, this awareness has clinical implications for IOP measurements and subsequent glaucoma management in DMEK patients.