Risk of corneal edema following glaucoma filtering surgery: a retrospective cohort study.

Objective: To compare the long-term risk of corneal edema after various glaucoma-filtering surgeries and to identify risk factors for its development.

Design: A retrospective cohort study.

Population: Adults undergoing glaucoma-filtering surgery by a single surgeon at Kingston Health Sciences Centre over a 20-year period.

Methods: Patients who underwent trabeculectomy, glaucoma drainage devices (GDD), Xen, and minimally invasive glaucoma surgery (MIGS) were included. Kaplan-Meier survival curves, and Cox proportional hazard models were generated to assess outcomes.

Results: A total of 333 eyes from 245 patients were included. Mean follow-up was 4.7 years (range: 3 months-19.3 years), and mean age was 73.9 years. The mean time from initial surgery to corneal edema onset was 6.2 years. The proportion of eyes free from corneal edema at 5, 10, and 15 years was 94.2%, 79.5%, and 70.8%, respectively. GDDs were associated with a higher risk of corneal edema compared to trabeculectomy (hazard ratio [HR]: 3.07, 95% CI: 1.03-9.17; p = 0.045). Five-year survival without corneal edema was 98.4% for Xen and 93.8% for MIGS. In multivariate analysis, neither Xen nor MIGS differed significantly from trabeculectomy. The number of glaucoma surgeries was the strongest predictor of corneal edema (HR: 2.40, 95% CI: 1.48-3.93; p = 0.0005).

Conclusions: GDDs increase the risk of corneal edema compared to trabeculectomy. Xen and MIGS offer lower-risk alternatives. The risk increases with multiple glaucoma surgeries.