Is the effect of intravitreal triamcinolone acetonide on diabetic macular edema dose-dependent?

Purpose: To determine whether the effect of intravitreal triamcinolone acetonide in diffuse diabetic macular edema is dose-dependent regarding the velocity and duration of macular edema reduction, visual acuity improvement, and induction of predictable complications. Methods: This clinical prospective study included 32 consecutive patients (32 eyes) with diffuse diabetic macular edema. All patients had visual acuity, fluorescein angiogram, and optical coherence tomography performed at the initial visit (baseline). Single triamcinolone acetonide injection was applied intravitreally in different high doses using sterile technique followed by timolol-maleate 0.5%/acetazolamide fixed combination eyedrops twice a day for 6 consecutive months. Macular edema, intraocular pressure, and best-corrected distance visual acuity were reviewed after 5 days and 1, 3, and 6 months. Results: Intraocular pressure did not change significantly during 6 months and was maintained within normal levels in all patients using prescribed antiglaucoma therapy. Best-corrected distance visual acuity and macular edema were better than preoperatively even 6 months after treatment while the highest improvement was recorded 1 month after treatment. There was a slight correlation of macular edema reduction and triamcinolone dose, especially in central 1-mm diameter zone 6 months post triamcinolone acetonide intravitreal injection, but it was not statistically significant. Conclusions: Triamcinolone intravitreal injection is a relatively safe, inexpensive, and effective method used for diabetic macular edema reduction but its effect is not proven to be dose-dependent, at least in 10-32 mg dose range. Macular edema reduction rate correlated significantly with preoperative edema.