Long-Term Outcomes and Safety of Non-Cyclodialytic, Bleb-Independent Surgical Enhancement of Uveoscleral Outflow in Open-Angle Glaucoma, with Evaluation of the Role of Conjunctival Lymphatic Vessels in Suprachoroidal Drainage

Purpose: To evaluate long-term outcomes and safety of non-cyclodialytic, bleb-independent surgical enhancement of uveoscleral outflow for intraocular pressure (IOP) reduction in open-angle glaucoma (OAG), and to assess the role of conjunctival lymphatic vessels (CLVs) in suprachoroidal drainage. Methods: In this single-center consecutive case series, 70 eyes of 63 patients (mean age 75.0 years; 70% female) with moderate-to-severe OAG underwent uveoscleral outflow enhancement. Twenty-two eyes had standalone surgery; 48 eyes had combined phacoemulsification with glaucoma surgery. Mean follow-up was 24.1 months (range 5.3–60.4). Primary outcomes were IOP reduction and surgical success by Kaplan–Meier analysis (sustained failure: IOP > 18 mmHg or < 20% reduction from baseline at two consecutive available postoperative visits, excluding day 1). CLVs were assessed by slit-lamp and OCT at 11 time points over 36 months. Mixed-effects models with random intercept per eye were used for repeated measurements. Logistic regression with cluster-robust standard errors evaluated predictors of CLV visibility. Results: Baseline IOP of 28.8 ± 8.4 mmHg decreased to 12.3 ± 4.5 mmHg at 1 month (54.5% reduction) and 14.5 ± 2.5 mmHg at 36 months (46.2% reduction, n = 22). Medications decreased from 2.77 ± 0.94 to 1.36 ± 1.09 at 36 months. Overall surgical survival was 91.4% at 1 month, 82.0% at 12 months, and 74.1% at 36 months. Fifteen eyes (21.4%) met sustained failure criteria (standalone surgery group: eight, combined surgery group: seven; and log-rank p = 0.065). The combined surgery group showed higher survival at 36 months (82.6% vs. 58.5%), but the difference did not reach significance. CLVs were detected in 51.4% by slit-lamp and 96.4% by OCT, peaking at 1 month. Before surgery, CLVs were not detected on OCT in any eye. Time was a significant negative predictor of CLV visibility on both slit-lamp (OR 0.953/month, p = 0.046) and OCT (OR 0.935/month, p = 0.003), without independent association with IOP or medication burden, suggesting that CLVs facilitate suprachoroidal drainage as a structural mechanism rather than a reactive response to IOP changes. Conclusions: Non-cyclodialytic, bleb-independent uveoscleral outflow enhancement provides sustained IOP reduction with favorable safety. CLVs, nearly universally detected by OCT after surgery, appear to contribute to suprachoroidal drainage. Combined surgery showed a trend toward greater surgical success than standalone procedures.