Biodegradable Intrascleral Implant of Triamcinolone Acetonide in Experimental Uveitis

Abstract

To evaluate the efficacy of a biodegradable intrascleral implant of triamcinolone acetonide (TA) in a rabbit model of experimental uveitis. A disc-shaped TA implant (1 x 3 mm, containing 6.4 mg of TA), which is made by poly(D,L-lactide) (PLA) and TA, was intrasclerally implanted into eight albino rabbits after a subcutaneous injection of tuberculin antigen. Control animals (n = 8) received sham devices. Uveitis was induced with an intravitreal injection of tuberculin antigen. To induce chronic inflammation, all eyes were reinjected with intravitreal antigen on day 14 and were observed for 1 month. Aqueous protein concentrations and cell counts were determined on days 7, 14, and 28. Inflammation of the anterior chamber (AC) and vitreous opacity were graded clinically and retinal functions were evaluated electroretinographically and histologically. Anterior chamber cells, flare, and vitreous opacity scores showed significantly less inflammation in treated eyes than in untreated eyes (P < 0.05). Quantitative analyses of aqueous cell counts and protein concentrations showed significant decreases in treated eyes (P < 0.05). Histopathologic examinations showed less severe inflammation and tissue disorganization in treated eyes. The biodegradable intrascleral TA implant was found to be effective at suppressing the inflammation induced by experimental uveitis in rabbits for at least 4 weeks.