Intraocular pressure (IOP) lowering efficacy of Bimatoprost Sustained Release (BimSR) in dogs pretreated with selective laser trabeculoplasty (SLT)

Abstract

Purpose : Selective Laser Trabeculoplasty (SLT) is a treatment for lowering intraocular pressure (IOP) in patients with glaucoma, however IOP lowering is not sustained after SLT over long term in a substantial proportion of patients. Additionally, recent studies found less reduction in IOP when SLT and topical prostaglandin analogues (PGA) were used in combination. Bimatoprost (a PGA) Sustained Release (BimSR) implant is currently in development as an IOP lowering agent delivered intracamerally (IC). The purpose of this study was to assess the efficacy of BimSR in both eyes of a cohort of dogs following unilateral SLT treatment.

Methods : Unilateral SLT was performed in 11 females, normotensive, drug-naïve beagle dogs. IOP was measured at baseline prior to SLT and then monitored weekly for up to 10 weeks following SLT. Between 6 - 10 weeks post SLT, nine of 11 eyes returned to their baseline IOP. Both eyes of all the animals were administered IC BimSR (15 μg) and IOP was measured every week for the first 4 weeks, then every two weeks up to 32 weeks. Percent change in IOP from baseline was calculated in both SLT-treated and naïve eyes, with data expressed as mean ±SE. A linear mixed effects model was used to evaluate the treatment effect of BimSR in both the SLT-treated eyes and the contralateral SLT-naïve eyes.

Results : BimSR was shown to be equally efficacious in lowering IOP in both SLT-treated eyes SLT- naïve eyes. Mean peak % decrease in IOP following BimSR administration to the SLT treated eye was 35.9%±2.2; mean peak % decrease was 35.6%±2.1 in the contralateral, SLT-naïve eye. Additionally, BimSR lowered IOP equally in eyes that responded to SLT (i.e., sustained decrease in IOP of ≥3 mmHg in the laser treated eye, n=6, mean peak IOP decrease, 36.0%±4.5) and eyes that did not respond to SLT treatment (i.e., decrease in IOP of ≤ 3 mmHg in the laser treated eye, n=5, mean peak IOP decrease, 36.2%±2.2).

Conclusions : Intracameral BimSR had substantial IOP-lowering effects in eyes previously treated with SLT, suggesting that eyes that have been treated with SLT can still benefit from intracameral drug delivery of a sustained release Bimatoprost implant. Importantly, BimSR was effective in lowering the IOP in eyes that were previously non-responders to SLT.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.