Background and Objective: Macular edema is an important cause of visual loss in diabetic patients which can lead to permanent vision loss in untreated cases. This study compares the efficacy of intravitreal injection and the sub-tenon capsule of triamcinolone on the visual acuity in patients with diabetic retinopathy.

Materials and methods: In this randomized clinical trial study, 82 diabetic retinopathy eyes were randomly assigned to intravitreal triamcinolone injection group and 74 eyes to sub tenon capsule injection. In terms of visual acuity and intraocular pressure, patients were followed up after first week, first month, and 3^rd month. The collected data were analyzed using ANOVA with repeated data (Repeated ANOVA) and  Stata software (version 13).

Results: Crude comparison between groups  did not exhibit significant differences. However, by controlling the confounding baseline effect, level of visual acuity, logMar[d1]  of the visual acuity in the  intravitreal injection group (-0.78) was significantly less than the sub-tenon capsule group (-0.67). Also, after controlling for other confounding variables (age and sex), the mean IOP was significantly higher in the intravitreal injection group.

Conclusion: [d2] Visual acuity in intravitreal injection group was significantly less than the sub-tenon capsule group and also the mean IOP was higher in the intravitreal injection group. Therefore, sub-tenon capsule of triamcinolone stands out as a superior approach.