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

Abstract

Purpose: To characterize long-term changes in corneal endothelial cells after phacoemulsification with or without supraciliary Micro-Stent (Alcon) implantation in eyes with open-angle glaucoma (OAG) and visually significant cataract.

Design: Three-year safety extension of a 2-year randomized clinical trial.

Methods: Patients from the multicenter Study of an Implantable Device for Lowering Intraocular Pressure in Glaucoma Patients Undergoing Cataract Surgery (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 ECDs in the microstent group (2,432.6 cells/mm² [95% confidence interval [CI], 2,382.8-2,482.4 cells/mm²]) were similar to those in the control group (2,434.5 cells/mm² [95% CI, 2,356.5-2,512.4 cells/mm²]) groups. ECL at months 48 and 60 was greater in the Micro-Stent group than in the control group. At month 60, the mean percent of changes in ECD was -20.4% (95% CI, -23.5% to -17.5%) in the Micro-Stent group and -10.1% (95% CI, -13.9% to -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 3 eyes with transient focal corneal edema and 4 eyes that required Micro-Stent trimming due to protrusion.

Conclusions: In eyes with OAG, ECL after phacoemulsification is acute and stabilizes after 3 months, whereas ECL after 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.