A Comparison of the Effectiveness of Triamcinolone Acetonide (TA) and a 5% Suspension of Poly–Lacticglycolic Acid (PLGA) on Visualization During Pars Plana Vitrectomy in Rabbits

Abstract

Purpose: : To compare TA and PLGA as visualization agents of the vitreous cortex during standard vitrectomy procedures and to assess residual pharmacologic effects following the procedure in pigmented rabbits.

Methods: : Dutch–Belted rabbits were divided into two groups of 3 each. After standard 20 gauge pars plana vitrectomy (PPV), one group received 4 mg TA in 0.1 ml and the other group received 0.1 ml of 5 % PLGA to visualize the vitreous cortex. TA or PLGA was removed with a subtotal vitrectomy and soft tip needle. Forty–eight hours after surgery, VEGF₁₆₅ (500 ng / 50 ul) was injected intravitreally via a 29 gauge needle to induce retinal vasculopathy and assess a pharmacological action of residual TA or PLGA. Follow–up at baseline and 48 hours after VEGF administration consisted of retinal color fundus imaging, fluorescein angiography and fluorophotometry to assess leak from the retina vasculature.

Results: : During vitrectomy, TA and PLGA worked similarly to visualize the VC. FA showed less retinal vessel leak in the TA group than in the PLGA group. Fluorophotometry area under the curve analysis showed a change from baseline of 3 ± 65% in the TA group and 487 ± 260% in the PLGA group.

Conclusions: : TA and PLGA are both efficient visualization agents during PPV. TA appears to have residual pharmacological activity 4 days after the procedure.

Keywords: corticosteroids • retina • vitreoretinal surgery