Background/

Objectives: To investigate changes in corneal endothelial cell density (CECD) after initial Ex-PRESS surgery in Japanese patients with open-angle glaucoma (OAG) followed-up for 36 months. Subjects/

Methods: Corneal specular microscopy was used to examine preoperative and postoperative (3, 6, 12, 24 and 36 months) CECD and CECD changes were analysed. Kaplan-Meier survival curve was used to examine CECD maintained at 95% level, and Cox proportional hazards model was used to detect the risk factors for CECD loss. Intraocular pressure (IOP) changes during the course were also examined.

Results: A total of 79 eyes of 79 patients (standalone surgery, 24 cases; combined cataract surgery, 55 cases) were investigated. Preoperative CECD (mean ± SD) was 2521 ± 305 cells/mm² and 2429 ± 366 (P = 0.003, adjusted for Bonferroni correction), 2462 ± 332 (P = 0.002), 2457 ± 317 (P < 0.001), 2433 ± 333 (P < 0.001), and 2387 ± 352 (P < 0.001) at 3, 6, 12, 24 and 36 months, respectively. The decrease rate was calculated as 1.8%/year. Further, 95% maintenance CECD at 36 months was 50.0% (95% confidence interval, 37.1-63.0%). Both univariate and multivariate Cox proportional hazard models showed that a low preoperative CECD was a significant risk factor for CECD loss. Baseline IOP of 19.3 ± 5.8 mmHg decreased at all measurement points (P < 0.001) after surgery.

Conclusion: CECD after initial Ex-PRESS surgery in 36 months might not be clinically problematic. However, longer-term follow-up is necessary, and regular CECD measurement should be performed, especially in patients with low CECD.