Impact of difficult unfolding and attachment of the graft lamella on the long-term outcome after Descemet membrane endothelial keratoplasty

Purpose Unfolding and attachment of the posterior donor lamella may be the most challenging part in Descemet membrane endothelial keratoplasty (DMEK) procedure. We investigated the correlation of the difficulty degrees of this step to the postoperative clinical outcome 6 years after surgery. Methods One hundred sixty-nine consecutive DMEKs between September 2012 and August 2013 at the Charite-University Medicine Berlin were graded prospectively into 4 groups according to their grade of difficulty in unfolding and attachment of the graft lamella. Postoperative visual acuity, endothelial cell density, and rate of graft failure were measured after 1 year, after 2 years, and after 6 years and analyzed according to their grading group. Results Visual acuity improved significantly in all groups and did not differ significantly between the grading groups at any time point postoperatively. There was a significant decrease of endothelial cell density in all groups with a significantly higher endothelial cell loss in group IV compared with the other groups within the first 24 months after surgery. The graft failure rate was significantly higher in eyes graded III and IV than in groups I and II (p= 0.012). Conclusion Although the endothelial cell loss and the graft failure rate increase significantly with a more difficult graft unfolding and attachment, DMEK surgery is a promising procedure with a good long-term postoperative outcome. A direct manipulation of the graft lamella for unfolding and centering by cannula or forceps should be avoided if possible to reduce the risk of an increased endothelial cell loss and a higher graft failure rate.