Effect of a modified rectus tuck on anterior segment circulation in monkeys

Removal of a rectus muscle results in permanent interruption of blood flow in the corresponding anterior ciliary artery, predisposing to anterior segment ischemia (ASI). A subhuman primate model of ASI was developed in order to study a novel muscle tuck procedure designed to preserve anterior ciliary artery circulation. Fluorescein angiograms were obtained before and after surgery to determine the effect of the muscle surgery on iris circulation. A total of 12 eyes from 12 cynomolgus monkeys underwent strabismus surgery consisting of tenectomy of all 4 rectus muscles in 3 eyes, tenectomy of 3 rectus muscles in 3 eyes, and tenectomy of 3 rectus muscles and muscle to sclera tuck of the remaining recti in 6 eyes. Postoperative angiograms documented preservation of perfusion in the distribution of the tucked muscle in all cases except one, in which there was iatrogenic trauma and disruption of anterior ciliary arteries. The modified tuck procedure thus appears to preserve anterior ciliary artery blood flow, and may be useful as a muscle strengthening procedure in patients predisposed to developing ASI.