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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 had 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.