Purpose:

Bimatoprost SR (BimSR) was designed to be placed intracamerally and provide slow release of bimatoprost to lower intraocular pressure (IOP) for 4–6 months. The objective of this analysis was to evaluate the rate of biodegradation of the implant and the relationship between implant degradation and IOP lowering in patients with glaucoma.

Methods:

Phase 1/2, 24-month, prospective, multicenter, dose-ranging, paired-eye trial in 75 open-angle glaucoma patients with study eye baseline mean IOP of 25.2 (range 22–36) mm Hg after washout. BimSR (6-, 10-, 15-, or 20-μg dose strength) was administered intracamerally in the study eye; the fellow eye received topical bimatoprost 0.03% QD. Rescue topical IOP-lowering medication or a single repeat treatment with implant was allowed. The investigator evaluated implant size in the inferior iridocorneal angle at follow-up visits using biomicroscopy and gonioscopy. The primary efficacy measure was IOP. Safety measures included corneal endothelial cell density (CECD).

Results:

All BimSR dose strengths effectively reduced IOP. IOP was controlled without rescue/retreatment in 68%, 40%, and 28% of BimSR-treated eyes up to 6, 12, and 24 months, respectively. Most implants administered at baseline were 76–125% of their initial size at assessments through month 6; 50% were 0–25% of their initial size at month 12; 70% were 0–25% of their initial size at month 24. At month 24 in BimSR-treated eyes that had not been rescued/retreated, the mean IOP was 16.9 mm Hg, and in 6 of 21 (29%) eyes, no residual implant was visible. Effects on IOP outlasted the implant. There were no significant differences in CECD between BimSR-treated and topically treated eyes.

Conclusions:

BimSR effectively reduced IOP with slow biodegradation of implants evident. Sustained IOP lowering through month 24, when residual implant was small or no longer visible, was seen in some eyes and potentially may be explained by durable remodeling of aqueous outflow pathways.