Transient central retinal artery occlusion after posterior sub-Tenon's anesthesia

Two cases of transient central retinal artery occlusion were observed preoperatively after uneventful sub-Tenon's infusion of local anesthetic for cataract surgery and intraocular lens implantation. In these eyes, the retinal circulation reperfused spontaneously before surgery and there were no visual sequelae. A third case was observed in an eye after strabismus surgery with sub-Tenon's anesthesia. The patient was left with profound visual loss in this eye. The cause of this complication is unknown, but possible factors include mechanical pressure from the bolus of the anesthetic solution or localized vasoconstriction from the anesthetic, producing a decrease in ocular blood flow. Suggestions to avoid this problem include not inserting the cannula too posteriorly, not injecting forcibly against resistance, and using the minimum volume of anesthetic possible.