Intravitreal Triamcinolone for Refractory Diabetic Macular Edema: A Randomized Climical Trial

To evaluate the effect of intravitreal triamcinolone acetonide (IVT) on clinical, angiographic, and optical coherence tomographic parameters in refractory diabetic macular edema (DME). In a double-masked placebo-controlled randomized clinical trial, 88 eyes of 61 patients with DME refractory to previous laser therapy or not suitable for such treatment were included in the study. Eligible eyes were randomly assigned into two groups. The treatment group (45 eyes) received 4 mg IVT and the placebo group (43 eyes) received subconjunctival injection of placebo. Complete ophthalmologic examination, fluorescein angiography, and optical coherence tomography (OCT) were performed before intervention and repeated after 2 and 4 months. Quantitative measurement of variables on angiograms including hard exudates (HE), size of foveal avascular zone, and leakage severity was performed using Photoshop software. Two months after intervention, visual acuity (VA) improved in the treatment group (-0.13 LogMAR, P=0.01) but slightly deteriorated in the placebo group (0.02 LogMAR, P=0.63). The difference of the above changes (0.15 LogMAR) was statistically significant at 2 months (P=0.02) but reduced to 0.11 LogMAR (P=0.08) after 4 months. Mean (standard deviation) of central macular thickness (CMT) by OCT before and 2 and 4 months after injection was 393 (151), 293 (109), and 362 (119) microns in the treatment group and 393 (166), 404 (134), and 405 (160) microns in the placebo group, respectively. The second month difference was statistically significant (P=0.01). Reduction of the amount of HE (51%, P=0.004) and petaloid pattern (P=0.012) was significant in the treatment group as compared with the placebo group. There was no significant IVT-related side effects except for transient ocular hypertension in 32.6% of patients after 2 months. The greatest therapeutic effect of IVT on DME according to CMT and VA occurs at 2 months and decreases up to the fourth month. However, concerning cyctoid macular edema and hard exudates, the effect is maintained up to 4 months.