A Comparison of Intravitreal versus Sub–Tenon’s Capsule Triamcinolone Acetonide Injection for Diabetic Diffuse Macular Edema

Abstract

Abstract: : Purpose: To compare the safety and efficacy of intraocular and sub–Tenon’s capsule injection of triamcinolone acetonide (TA) for diffuse diabetic macular edema. Methods: Prospective, double–masked, randomized clinical trial. One eye of twelve patients (24 eyes) with symmetric diffuse bilateral diabetic macular edema was randomly assigned to receive a single 4–mg triamcinolone acetonide intravitreal injection, whereas the fellow eye received a 40 mg triamcinolone acetonide sub–Tenon’s capsule injection.Main outcome measures were changes in visual acuity and central macular thickness obtained using optical coherence tomography through a 6–month follow–up. Potential treatment complications were monitored, including intraocular pressure increase and cataract progression. Results: Both intravitreal and sub–Tenon injections of triamcinolone acetonide resulted in significant but transient improvements in visual acuity and central macular thickness. The mean (±SD) central macular thickness in the intravitreal–injected eyes was statistically significant thinner than in the sub–Tenon’s capsule–injected eyes at 1 month (226.8±41.7 µm vs 431.5±165.8 µm, respectively; P=0.002) and 3 months (242.3 ± 93.9 µm vs 364.7±78.2 µm, respectively; P=0.005) after triamcinolone acetonide injection. The mean visual acuity (logMAR) in the intravitreal injected eyes was statistically significant better than in the sub–Tenon injected eyes at 3 months (0.832±0.293 vs 1.107±0.339, respectively; P=0.004) after triamcinolone acetonide injection. Intraocular pressure did not show any significant difference between the two–triamcinolone acetonide delivery approaches at any follow–up visit and no eyes had intraocular pressures above 25 mmHg. Conclusions: The findings from our study neither advocate nor support the use of corticosteroids for the treatment of diabetic macular edema, but implies that both sub–Tenon and intravitreal triamcinolone acetonide injections may be equally tolerated with a short term performance clear favoring the intravitreal (4mg) over sub–Tenon’s capsule (40 mg) route for all quantifiable anatomic and functional aspects of improvement tested in this investigation.

Keywords: diabetic retinopathy • macula/fovea