To retrospectively evaluate the clinical effect of intravitreal (IVT) and posterior subtenon (PSTT) triamcinolone acetonide (TA) injection in diabetic macular edema.

Fifty eyes of 43 patients with diabetic macular edema (DME) were included. Twenty-two eyes in the IVT group received 4 mg/0.1 ml intravitreal TA injections and 26 eyes in the PSTT group received 40 mg/1.0 ml subtenon TA injections. LogMAR visual acuity and intraocular pressure (IOP) were measured and, using OCT, central macular thickness (CMT) and total macular volume (TMV) were also measured before and 1, 3, and 6 months postoperatively.

Both groups showed significant decreases in the mean CMT and TMV. The mean CMT in the IVT group was significantly thinner than that of the PSTT group 1 month postoperatively. The percentage reduction in CMT and TMV were also greater in the IVT group than the PSTT group 1 month postoperatively. Both groups showed significant improvements in mean visual acuity, with no significant difference between the two groups. However, at 1-month postoperative improvement in visual acuity was significantly greater in the IVT group than the PSTT group. The mean IOP in the IVT group was also greater than that in the PSTT 1 month postoperatively.

Both injections caused a significant increase in visual acuity and a decrease in CMT and TMV. The effect was more pronounced in the IVT group. However, the PSTT injection also appeared to be a safe and effective technique for the treatment of DME.