Posterior sub-tenon triamcinolone for refractory diabetic macular edema: a randomized clinical trial

To evaluate the effect of posterior sub-tenon triamcinolone acetonide (TA) injection on clinical, angiographic, and optical coherence tomographic (OCT) parameters in refractory diabetic macular edema (DME). In a double-masked placebo-controlled clinical trial, 64 eyes were randomly assigned to two groups. The treatment group (32 eyes) received 40 mg posterior sub-tenon injection of TA and the placebo group (32 eyes) received subconjunctival injection of a placebo. The injections were repeated after 2 months in both groups. Complete ophthalmologic examination, fluorescein angiography, and OCT were performed before intervention and after 4 months. Quantitative measurement of angiographic variables such as the amount of hard exudates (HE), size of foveal avascular zone (FAZ), and leakage severity was performed by computer, using Photoshop software. Initial best-corrected visual acuity (VA) was 0.93+/-0.39 logMAR in the placebo group and 0.75+/-0.38 logMAR in the treatment group. At 4 months, corrected VA was 0.88+/-0.48 logMAR in the controls versus 0.71+/-0.42 logMAR in the cases. Mean central macular thickness measured by OCT before and 4 months after injection was 392 and 377 microns in the treatment group and 388 and 357 microns in the placebo group, respectively. No statistically significant difference was detected between the two groups. The difference was also not significant in HE, FAZ, and leakage in the angiograms. Two injections of posterior sub-tenon TA had no therapeutic effect on refractory DME.