Date of Award

January 2026

Document Type

Thesis

Degree Name

Medical Doctor (MD)

Department

Medicine

First Advisor

Ji Liu

Abstract

Abstract

BackgroundRecent advancements in minimally invasive glaucoma surgery have included the ab externo open conjunctival method for XEN stent insertion. The Xen Gel Microstent is a subconjunctival microinvasive glaucoma device developed with the aim of creating a filtering bleb and bypassing the trabecular meshwork. The device has been found to have efficacy and safety in a variety of patient populations. This study evaluated the impact of technique modifications including tenonectomy, combined phacoemulsification, and mitomycin C delivery method on surgical outcomes in open-angle glaucoma.

MethodsThis retrospective cohort study assessed eyes with open-angle glaucoma that underwent open conjunctival ab externo XEN45 Gel Stent implantation at a single academic center between April 2021 and September 2023, with outcomes assessed through 12 months postoperatively. The cohort included eyes treated with mitomycin C via subtenon injection or sponge application, with or without tenonectomy and with or without concomitant cataract extraction. Baseline characteristics were compared. Inclusion criteria included age ≥18 years and preoperative IOP >17 mmHg. The primary outcome was defined as achieving an IOP ≤21 mmHg with ≥20% reduction from baseline, with or without IOP-lowering medications, at 1 year. Secondary analyses examined IOP, IOP-lowering medications, visual acuity (VA), and postoperative complications and interventions over time.

ResultsAt 12 months, qualified surgical success did not differ across technique variations, including tenonectomy, MMC delivery method, and combined phacoemulsification. MMC injection was associated with lower early postoperative IOP and a greater reduction in medication burden compared with sponge application, while IOP outcomes were similar by 12 months and late complications occurred exclusively in the sponge group. Combined phacoemulsification and standalone XEN45 demonstrated comparable success rates and long term IOP reduction, although combined cases had higher immediate postoperative IOP and fewer postoperative interventions. Tenonectomy was not associated with improved IOP lowering and showed a trend toward higher early complication rates with fewer postoperative interventions and reoperations.

Conclusions:All methods significantly reduced IOP and preserved VA similarly. Differences between techniques were primarily observed in the early postoperative period rather than in long-term efficacy. MMC delivery method, concomitant phacoemulsification, and tenonectomy influenced early IOP control, medication burden, and postoperative course without altering overall success rates. These findings support tailoring surgical technique to individual patient characteristics.

Comments

This thesis is restricted to Yale network users only. It will be made publicly available on 07/14/2028

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