Background To determine the incidence and potential risk factors of cystoid macular oedema (CMO) following Descemet membrane endothelial keratoplasty (DMEK) with or without simultaneous cataract surgery.

Methods In this study, 155 eyes of 88 patients suffering from Fuchs endothelial dystrophy (81%), bullous keratopathy (17.6%) or other corneal diseases (1.4%) underwent DMEK. 52% were pseudophacic (DMEK) and 48% received simultaneous cataract surgery (DMEK combined with cataract surgery (Triple-DMEK)) at the Eye Center at Albert Ludwigs University of Freiburg between May 2011 and June 2013. Spectral-domain optical coherence tomography (SD-OCT) was performed 6 weeks, 3 months and 6 months following (Triple-)DMEK and in unscheduled visits due to limited or decreased visual acuity. The medical records were reviewed for pre-existing comorbidities limiting visual acuity. Patients with a history of macular oedema were excluded. We estimated the incidence of CMO using the Kaplan–Meier method. Potential risk factors for CMO were analysed with a Cox regression analysis and Pearson's correlation. The Cox model included the following variables: patient age and axial length, simultaneous cataract surgery, rate of rebubbling, donor age and donor endothelial cell density.

Results 13% of all eyes developed a single episode of CMO at the end of the follow-up. After 6 months, 13.3% of eyes following Triple-DMEK and 12.5% of eyes following DMEK showed CMO. There was a statistically significant correlation between CMO development and best spectacle corrected visual acuity. Long axial length had a protective effect on CMO development (HR=0.3; p=0.03). Under medical therapy, central foveal thickness decreased in all patients. CMO did not have a relevant effect on long-term visual acuity.

Conclusions CMO is a frequent complication following DMEK in phacic and pseudophacic eyes. The prognosis is excellent given medical treatment. We recommend regular SD-OCT monitoring during the first 6 months following DMEK.