Intravitreal Triamcinolone Acetonide Suppresses Concanavalin–A Induced Posterior Eye Segment Inflammation and Retinal Blood Barrier Breakdown

Abstract

Purpose: : Concanavalin A (ConA) is a potent mitogen, which elicits vascular and retinal degeneration, breakdown of the blood–retinal barrier (BRB), and induces posterior eye segment inflammation subsequent to intravitreal injection. Recently the corticosteroid triamcinolone acetonide (TA) has become available for treatment of macular edema, diabetic retinopathy and retinal vein occlusion. It has been suggested that these types of retinal edema occur as the consequence of the breakdown of BRB. Accordingly, we evaluated the anti–inflammatory effect of intravitreal TA in an animal model of posterior eye segment inflammation.

Methods: : ConA (10, 30, 100 µg/eye) or vehicle (sterile saline) was injected intravitreally in the anesthetized male Dutch rabbit, to induce posterior eye segment inflammation. Thirty microliters of TA in a sterile saline suspension was injected into the vitreous (0.3, 1.2, 2.4 mg/eye) two days before. Seven days after ConA injection measurement of protein concentration in the vitreous body assessed BRB breakdown. Furthermore, we also compared the efficacy of TA with other steroids in lessening inflammation.

Results: : ConA injection elicited dose–dependent increases in vitreal protein over a range from 2.1, 5.3, and 6.9 mg/mL compared with the contralateral eye injected with 0.2 mg/mL of vehicle. Moreover, TA intravitreal injection before inflammation induction dose–dependently suppressed the protein increase in the vitreous body caused by 30 µg/eye ConA injection. The largest declines in protein concentration following 2.4 mg/eye TA treatment exceeded 80%.

Conclusions: : TA treatment ameliorated ConA induced inflammation and increases in vitreal protein concentration. Therefore, it appears that TA intravitreal injection is an effective approach to treat posterior eye segment inflammation associated with retinal edema resulting from BRB breakdown.

Keywords: retinitis • corticosteroids • vitreous