Corneal Endothelial Cell Changes After Phacoemulsification Combined with Excisional Goniotomy with the Kahook Dual Blade or iStent: A Prospective Fellow-Eye Comparison

PURPOSE: To characterize changes in endothelial cell density and morphology following phacoemulsification combined with either excisional goniotomy with the Kahook Dual Blade (KDB-phaco) or first-generation iStent trabecular microbypass implantation (iStent-phaco). SETTING: A single clinical practice. METHODS: Twenty-one adult subjects from one center with visually significant cataract and mild-moderate open-angle glaucoma underwent KDB-phaco or iStent-phaco in one eye and the alternate procedure in the fellow eye as part of a prospective, multicenter, randomized trial. Specular microscopy and pachymetry were performed before and 6–29 months after surgery. Parameters analyzed included change from baseline of endothelial cell density (ECD), the coefficient of variation (CV), the percent of hexagonal cells (%HEX), and central corneal thickness (CCT). RESULTS: Baseline ECD, CV, %HEX, and CCT were similar between groups. A mean (standard deviation) of 18.2 (5.8) months postoperatively (range 12.5–28.7 months), the change from baseline in ECD was −90 ± 226 cells/mm(2) (−3.4%) in KDB-phaco eyes (p=0.083) and −239 ± 247 cells/mm(2) (−9.0%) in iStent-phaco eyes (p<0.001); the change in iStent-phaco eyes was significantly greater than in KDB-phaco eyes (p=0.013). The magnitude of Endothelial Cell Loss (ECL) was not correlated with length of postoperative follow-up time in either group. No significant differences in change from baseline in CV, %HEX, or CCT were noted with the exception of a decrease in %HEX in iStent-phaco eyes (p=0.017). No eyes manifested corneal edema, decompensation, or other cornea-related complications. CONCLUSION: Both KDB-phaco and iStent-phaco are associated with postoperative ECL, with iStent-phaco producing significantly greater ECL than KDB-phaco. The clinical significance of these findings is unclear, and future studies are warranted to more robustly characterize long-term effects of glaucoma surgical procedures—with and without permanent implants—on ECD and corneal health and to develop evidence-based guidelines for the pre- and post-operative evaluation of corneal health in eyes undergoing glaucoma surgery.