Corneal Endothelial Cell Loss and Morphometric Changes 5 Years after Phacoemulsification With or Without CyPass Micro-Stent

Abstract Purpose To characterize long-term corneal endothelial cell changes following phacoemulsification with or without supraciliary micro-stent (CyPass, Alcon, Ft. Worth, TX) implantation in eyes with open-angle glaucoma (OAG) and visually-significant cataract. Design Three-year safety extension of a two-year randomized clinical trial. Methods Patients from the multicenter COMPASS trial who underwent micro-stent implantation plus phacoemulsification (n=282) or phacoemulsification alone (n=67) were analyzed post-hoc. Specular microscopy was used to assess endothelial cell loss (ECL), including changes from baseline in endothelial cell density (ECD), coefficient of variation, and percentage of hexagonal cells,. Results Preoperative ECD was similar in the microstent (2432.6 cells/mm2 [95% CI: 2382.8, 2482.4]) and control (2434.5 cells/mm2 [95% CI: 2356.5, 2512.4]) groups. ECL at Months 48 and 60 was greater in the micro-stent than in the control group. At Month 60, mean percent changes in ECD were -20.4% (95% CI: -23.5%, -17.5%) in the micro-stent and -10.1% (95% CI: -13.9%, -6.3%) in the control group. No statistically significant between-group changes from baseline in cellular morphology were observed. Nine adverse events were possibly related to ECL, including three eyes with transient focal corneal edema and four eyes that required micro-stent trimming due to protrusion. Conclusions In eyes with OAG, ECL following phacoemulsification is acute and stabilizes after 3 months, whereas ECL following phacoemulsification plus micro-stent implantation proceeds for at least 5 years. Clinical findings associated with ECL in these eyes were uncommon (3.3% of implanted eyes), suggesting that ECL is generally a subclinical phenomenon.