Ab Externo Continuous Pressure Technique for Descemet Membrane Endothelial Keratoplasty in Vitrectomized Eyes

INTRODUCTION: Descemet membrane endothelial keratoplasty (DMEK) in vitrectomized eyes presents a significant surgical challenge, as the compromised counter-pressure of the iris-lens diaphragm impedes proper shallowing of the chamber, complicating graft unfolding and centration. To address this challenge, surgeons often pivot to descemet's stripping automated endothelial keratoplasty (DSAEK). DMEK superior visual outcomes, fast rehabilitation and low rejection risk, have prompted the exploration of tailored DMEK techniques in vitrectomized eyes. This study describes a novel technique, which consists of continuous external pressure on the corneal surface while unfolding and orienting the graft with minimum graft manipulations and no additional devices. METHODS: A case series of eight eyes from patients with an average age of 68±13 who underwent DMEK surgery with the novel ab externo continuous pressure technique is described. Visual acuity outcomes were assessed preoperatively and at one-year follow-up. Complications were assessed to date and up to seven years following operation with the ab externo continuous pressure DMEK technique. Data was analyzed using a student's t-test. RESULTS: All corneas cleared postoperatively and remained clear through twelve months of follow-up. Implementation of the continuous pressure technique allowed proper unfolding and centration of DMEK grafts in all these challenging cases. Best corrected visual acuity following surgery improved significantly from an average of logMAR 1.05±0.12 to logMAR 0.3±0.16 (p=0.003) with no intra-operative complications. Three patients underwent re-bubbling (37.5%), and one patient experienced late graft failure at three years postoperatively. CONCLUSIONS: The ab externo continuous pressure technique for DMEK in vitrectomized eyes is effective, safe and relatively easy to adopt. The technique requires no additional instrumentation and minimizes graft handling, offering a valuable option for managing these challenging cases.