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Comparison of the Efficacy and Safety of Different Methods of Posterior Subtenon Injection

Purpose: To compare the safety and efficacy of different methods of posterior subtenon (PST) injection of corticosteroids in the treatment of cystoid macular edema secondary to intermediate uveitis. Design: Prospective comparative randomized interventional study. Participants: A total number of 30 eyes with cystoid macular edema secondary to intermediate uveitis were examined. Methods: Patients were randomized into 3 treatment groups of 10 eyes each. Each group received PST injection of triamcinolone acetonide 0.5 mL (20 mg) by one of three methods: cannula method (group 1), Smith and Nozik method (group 2), or orbital floor injection method (group 3). Patients underwent Snellen's and ETDRS visual acuity (VA) testing, clinical evaluation, optical coherence tomography (OCT), and fundus fluorescein angiography (FFA) at baseline and follow-up visits. Outcome measures: Changes in Snellen and ETDRS VA, OCT retinal thickness and assessments of safety were recorded in follow-up visits. Results: Postintervention patients were followed up at the 1st, 2nd, 6th, and 12th weeks. Statistically significant (p = .00) improvement in VA was present in group1 from 0.25 ± 0.08 (mean ± standard deviation) to 0.75 ± 0.24, in group 2 from 0.29 ± 0.12 to 0.78 ± 0.23, and in group 3 from 0.24 ± 0.10 to 0.72 ± 0.27. Statistically significant decrease in OCT central macular thickness (43.97% in group 1, 32.46% in group 2, and 29.75% in group 3) was noted at 12 weeks. However, the difference between individual groups at each visit did not reach statistical significance. Steroid-induced rise in intraocular pressure was observed in all the three groups with no statistical difference between individual groups. Conclusions: The different methods of PST injection are equally efficacious in terms of improving visual acuity. However, the cannula method achieves the greatest quantitative reduction in macular thickness. As the cannula method is as efficacious as Smith and Nozik method it may be a preferable method to deliver posterior subtenon injection of corticosteroids.