Efficacy of posterior sub-tenon's capsule injection compared to intravitreal injection of triamcinolone acetonide for treatment of diabetic macular edema: A systematic review and meta-analysis

Background: Diabetic macular edema (DME) is defined as a retinal thickening in one-disc diameter of the center of the macula. It is a number of microvascular retinal changes that lead to blood-retinal barrier disruption, causing leakage of fluid and plasma components into the inner and outer plexiform layers. Aim of the Work: To conduct a systematic review and a meta-analysis estimating the efficacy and complications of posterior sub-Tenon's capsule injection of triamcinolone acetonide (STTA) compared to intravitreal injection of triamcinolone acetonide (IVTA) for management of DME. Materials and Methods: A comprehensive literature search was conducted using the databases Google Scholar, PubMed, MEDS, web of science, EMBASE, and Cochrane Library for published studies from January 01, 2000 to September 01, 2019. This meta-analysis included ten studies. They were randomized controlled clinical trials, and about 343 patients with DME (469 eyes) participated in these studies. Results: This study demonstrated a statistically significant change in the mean of best-corrected visual acuity (BCVA) improvement and central macular thickness (CMT) reduction in both groups when comparing the baseline to 1- and 3-month follow-ups after the injection, though with no statistically significant difference in the IVTA compared to the STTA group. At a 6-month follow-up, both groups showed no significant differences in the BCVA and CMT compared to the baseline. Both groups showed no statistical differences in the BCVA or CMT over the follow-up periods. Regarding intraocular pressure (IOP) changes, the present study showed that the mean IOP was elevated in both groups at 1- and 3-month follow-ups after the injection compared to their baseline. There was a statistically significant difference between both groups at 1 and 3-months. The IOP was more elevated in the IVTA compared to the STTA group. At a 6-month follow-up, both groups showed no significant difference in the IOP elevation compared to the baseline. IOP elevation was the most reported adverse effect in all included studies. Cataract formation is also reported in some studies, though no other complications, such as endophthalmitis, vitreous hemorrhage, and/or retinal detachment, are reported in any of the studies. Conclusion: STTA injection has a comparable effect to the IVTA injection and carries a lower risk of intraocular complications. It is considered an easy, safe, and valid alternative to intravitreal injection for the treatment of DME.