Sheathotomy vs. Intravitreal Triamcinolone for Branch Retinal Vein Occlusion

In each sheathotomy patient, a standard pars plana vitrectomy is performed, followed by surgical separation of the posterior cortical vitreous from the optic nerve and posterior retina. After the relevant arteriovenous crossing site is identified based on preoperative FA, a bent microvitreoretinal blade is used to open the internal limiting membrane and the nerve fiber layer over the artery, with the incision commencing 100-200 micrometer proximal to the AV crossing. The incision is continued parallel to and under the retinal arteriole, with a gentle lifting motion, until the common AV crossing sheath is encountered and incised in a side-to-side manner. The completion of AV dissection is confirmed by an elevation of the overlying artery.

The IVTA group receive intravitreal injection of 4 mg/0.1 mL triamcinolone acetonide (40 mg/mL; Tamceton®; Hanall Pharmaceutical, Seoul, Korea). The injections are performed using 0.5% proparacaine drops (Alcaine®; Alcon Laboratories, Fort Worth, TX) for topical anesthesia under sterile conditions. The drug is injected through the inferotemporal pars plana using a 30-gauge needle. The correct intravitreal localization of the suspension, and perfusion of the optic nerve head, are then confirmed by indirect ophthalmoscopy.