A novel bioerodible deep scleral lamellar cyclosporine implant for uveitis.

The research investigates the suitability and effectiveness of a unique, biodegradable, sustained release implant of the drug cyclosporine (CsA) for treating uveitis. The study finds that when the implant is placed deep in the equine (horse) eye, it effectively controls the condition and maintains therapeutic levels of the drug.

Study Objectives and Methodology

• The primary aim of the study was to examine the safety, practicality, and effectiveness of a sustained release CsA device placed in sub-surface eye tissue (episcleral or deep scleral) in a naturally occurring animal (horse) model of uveitis.
• To do this, they employed a two-compartment perfusion chamber to assess the permeability of fluorescein, dexamethasone-fluorescein, or CsA across human and equine sclera (white part of the eye) in vitro (lab conditions).
• They then designed a biodegradable CsA implant and estimated the rate of CsA release in vitro. They also measured tissue CsA levels in eyes that were implanted with the device.
• Lastly, they monitored horse eyes with the implant for up to three years to assess long-term performance and effects.

Study Results

• The study found that dexamethasone-fluorescein and CsA penetrated the equine sclera poorly under lab conditions. However, when tested in live horses, low but detectable levels of CsA were found in the eye.
• When the implant was positioned episclerally (just under the surface of the eye’s white part), it was not effective in controlling inflammatory episodes in horses with ERU (equine recurrent uveitis).
• When the implant was positioned in the deep sclera (deeper in the eye) and next to the suprachoroidal space, it resulted in high levels of CsA in most ocular tissues. This positioning resulted in a significant decrease in the frequency of uveitic flare-ups in clinical equine patients with ERU.

Conclusion

• The study concluded that delivery of CsA to the equine eye via diffusion from the episcleral space was not a feasible method of drug delivery.
• However, the study also found that placing a deep scleral lamellar CsA implant adjacent to the suprachoroidal space was effective in achieving therapeutic ocular drug concentrations and controlling uveitis in horses with ERU.