Abstract
Abstract: :
Purpose: Sustained delivery of cyclosporine A (CsA) has been an effective therapy in several animal models of uveitis. The purpose of this study is was to describe the surgical placement and complications of a matrix-reservoir CsA device in the suprachoroidal space in horses with chronic recurrent uveitis. Methods: The 6-mm diameter, 3-mm thick CsA device was composed of a 10 mg pressed pellet of CsA surrounded by a 15% matrix of CsA in PVA. In vitro CsA release rates from these devices in PBS revealed an initial burst (5 ug/day) of CsA for 7 days followed by a steady state release (2 ug/day) measured for 4 months. Horses with documented immune-mediated recurrent uveitis were selected for implantation. A 1 cm conjunctival incision was made in the dorsolateral bulbar conjunctiva. A 7-mm diameter scleral flap was made approximately 8 mm posterior to the limbus immediately temporal to the insertion of the superior rectus muscle exposing the external aspect of the pars plana , choroid, and suprachoroidal space. The cyclosporine A-containing device was placed beneath the scleral flap within the suprachoroidal space. Scleral and conjunctival incisions were closed with 6-0 vicryl. Patients were reevaluated at 1 month, 3 months, 6 months and 12 months after implantation. Results: To date, 18 horses have been implanted with a mean follow up of 4.2 months. No immediate intra or post-operative complications were encountered. On reevaluation, the devices remained in their original location with no evidence of scleral or intraocular reaction. Conclusions: Suprachoroidal placement of a diffusible drug delivery device was well tolerated in a naturally occurring model of recurrent uveitis. The rate of complications was lower than that seen in the same model using vitreal based diffusion devices (e.g., intraocular hemorrhage, retinal detachment, implant migration). Further study is also underway to determine the long-term effectiveness of the suprachoroidal placement of the device in control of uveitis.
Keywords: cyclosporine • uveitis-clinical/animal model • drug toxicity/drug effects