Evaluation of the Bimatoprost Sustained Release Implant (DURYSTA®) After Posterior Chamber Implantation

Background: The Bimatoprost intracamerial implant (DURYSTA®) is currently only approved as a single-use device due to concerns of progressive loss of corneal endothelial cells following repeated intracameral administration. Currently depot systems such as DURYSTA® are placed in the anterior chamber, however the anterior chamber’s open environment allows for unrestricted movement of implants that results in corneal endothelial cell loss. Delivery of the implant to the posterior chamber may offer a means of providing similar or elevated levels of drug to the primary target, the ciliary body, while also isolating the implant from the cornea. This in turn may provide a means of safe serial administration. Materials and Methods: To assess migration after intracameral and posterior chamber DURYSTA® administration, a comprehensive analysis using a variety of imaging including optical coherence tomography, robotic ultrasound and slit lamp biomicroscopy video recordings were performed. Six patients (n=10 eyes) received a single DURYSTA® implant in the posterior chamber of one or both eyes. Intraocular Pressure (IOP) was measured after washout of all glaucoma medication at baseline, 1 week, 1 month and 3 months post-implantation. Paired t-tests, Cohen’s d and Hedge’s g compared each follow-up IOP to baseline. Finally, relative IOP lowering after posterior chamber administration was compared against reported IOP lowering in the ARTEMIS trials. Results: For posterior chamber implant imaging, only robotic ultrasound was satisfactory for DURYSTA® visualization. Robotic ultrasound confirmed that in ten pseudophakic eyes, the implant was held well positioned, sandwiched between the iris and pseudophakic lens complex. Mean baseline Average IOP was 24.9 ± 6.66 mmHg. Average IOP was recorded 16.4 ± 5.1 mmHg at 1 week, 13.1 ± 4.1 mmHg at 1 month and 15.2 ± 4.2 mmHg at 3 months. Paired t-tests revealed statistically significant reductions at all time points with confirmation of meaningful IOP lowering despite small sample size by Cohen’s d and Hedge’s g. IOP lowering by DURYSTA®, was found to be non-inferior with posterior chamber administration as compared to intracameral administration data from the ARTEMIS trials. Conclusion: Posterior chamber administration of DURYSTA® provided IOP lowering comparable to intracameral administration with no noted adverse events. ArcScan robotic ultrasound imaging confirmed stable implant positioning sandwiched between the iris and pseudophakic lens complex. This approach of delivery of implants to the posterior chamber merits further investigation as a novel implant location for ocular drug-delivery platforms to maintain efficacy while potentially reducing adverse events and opening up the possibility of serial administration.