Efficacy of ab-interno gelatin microstent implantation in primary and refractory glaucoma

To evaluate the outcomes of ab interno gelatin microstent implantation alone and in combination with phacoemulsification for the reduction of intraocular pressure (IOP).

Retrospective cohort study.

141 eyes of 141 patients with any glaucoma subtype, including refractory glaucoma, operated in the Centre Hospitalier de l'Université de Montréal (CHUM) from 2015-2018. Patients were included if they were over 40 years of age and had a preoperative IOP of >18 mm Hg on maximum tolerated medical therapy.

All patients received ab-interno microstent implantation (XEN-45, Allergan, Madison, NJ) with mitomycin C +/- combined phacoemulsification. The primary outcome was complete surgical success (IOP 6-18 mm Hg and <20% reduction from baseline without IOP medications or reoperations or cyclophotocoagulation); secondary outcomes included qualified success allowing for medications, percentage reduction in mean IOP and medications, and reduction in number of complications, interventions, and reoperations.

Mean follow-up was 30.5 ± 10.2 months (±SD). Mean IOP was 23.3 ± 7.0 mm Hg on 3.4 ± 0.8 medications at baseline and 13.3 ± 4.7 mm Hg on 1.9 ± 1.5 medications at 24 months of follow-up (p < 0.001). From 24-month survival analysis estimates, complete success was achieved in 34.1% of microstent eyes versus 20.7% with combined phacoemulsification (p = 0.02); 79.1% versus 75.1% achieved qualified success, respectively (p = 0.86). Cases with combined phacoemulsification had a higher rate of failure (hazard ratio [HR] = 1.6, 95% CI 1.1-2.3, p = 0.02). Needling with mitomycin-C or 5-fluorouracil postoperatively occurred in 54 eyes (38.3%). Complications included transient hypotony (10.6%), transient hyphema (6.4%), macular edema (4.3%), and microstent exposure (2.8%). There were 33 eyes (23.4%) with reoperations and 14 (9.9%) requiring subsequent cyclophotocoagulation lasers.

Microstent implantation required topical therapy in most cases 24 months following surgery in primary and refractory glaucoma and, when combined with phacoemulsification, had a higher risk of failure.