The transient efficacy of a single intravitreal triamcinolone acetonide injection for diabetic macular edema

Background: The major cause of visual impairment in diabetic patients is macular edema. The failure of laser photocoagulation in a large subgroup of patients with clinically significant diabetic macular edema has prompted interest in other treatment methods. Objectives: To evaluate the long-term efficacy and safety of an intravitreal injection of triamcinolone acetonide for clinically significant diabetic macular edema. Methods: In a retrospective case series 31 diabetic patients with persistent, recurrent or diffuse clinically significant diabetic macular edema received a single 4 mg (0.1 ml) intravitreal triamcinolone acetonide injection and were followed for at least 6 months, The main outcome measures evaluated were classified as primary: visual acuity and central macular thickness, and secondary: intraocular pressure and cataract progression. Statistical analysis included Student's t-test, chi-square test and the MacNamar test. Results: Best visual acuity results were observed 2.6 +/- 2.4 months post-injection. At that time the mean foveal thickness ha decreased by 37% from a baseline of 455 +/- 100 to 288 +/- 99 mu (P < 0.001) and the mean visual acuity improved from 6/42 to 6/23 (P < 0,001). Final mean visual acuity after an average of 10 +/- 1.8 months follow-up (range 6-13 months) was identical to the baseline, although mean foveal thickness was still significantly lower than the initial thickness (368 +/- 166 vs. 455 +/- 100 mu, P < 0.01). Statistical analysis did not identify any pre-injection prognostic factors for improved visual acuity. The only complications that occurred were elevated intraocular pressure in 42% of patients and cataract progression in 21%. There was no endophthalmitis. Conclusions: Intravitreal injection of triamcinolone acetonide for clinically significant diabetic macular edema is effective in reducing foveal thickness and improving visual acuity in the short term. Longer follow-up revealed that visual acuity returned to pre-injection values, even though a modest decrease in the foveal thickness persisted. Further studies are needed to evaluate the long-term efficacy in conjunction with laser photocoagulation treatment.