Treatment of Experimental Anterior and Intermediate Uveitis by a Dexamethasone Intravitreal Implant

PURPOSE. To assess the efficacy of a dexamethasone (DEX) intravitreal implant in a rabbit model of anterior and intermediate uveitis. METHODS. Experimental anterior and intermediate uveitis was induced by a unilateral intracameral injection of Mycobacterium tuberculosis H37Ra antigen in preimmunized rabbits. Four days after uveitis induction, rabbits received DEX implant or underwent a sham procedure (no implant). Clinical and histopathologic signs of uveitis were assessed for 13 days, and levels of inflammatory markers in the iris/ciliary body were measured after 21 days. RESULTS. All signs of anterior and intermediate uveitis were reduced by the DEX implant compared with sham procedure. At day 13, mean anterior chamber cell scores +/- SD for the DEX implant versus the sham procedure were, respectively, 1.9 +/- 1.3 versus 4.0 +/- 0.0 (P = 0.04), and mean total histologic inflammatory scores were 3.9 +/- 2.5 versus 15.4 +/- 6.0 (P = 0.026). Similarly, at day 13, mean vitreous haze severity scores (SD) for the DEX implant versus the sham procedure were, respectively, 0.1 +/- 0.2 versus 2.7 +/- 1.5 (P = 0.026), and mean vitreous inflammatory cell infiltration scores were 0.0 +/- 0.0 versus 1.5 +/- 1.3. Treatment with the DEX intravitreal implant also significantly reduced the proinflammatory immune response, as measured by cytokine levels in iris/ciliary body. CONCLUSIONS. A single administration of DEX implant significantly reduced inflammation in an animal model of anterior and intermediate uveitis. (Invest Ophthalmol Vis Sci. 2011;52:2917-2923) DOI:10.1167/iovs.10-5939