In ocular ischemic syndrome, the ischemic condition is due to markedly reduced blood flow and increased vascular resistance of retrobulbar circulation, as in the central retina and posterior ciliary arteries. Chronic hypoxia affects even the iris and ciliary body. The hypoperfusion of the ciliary body leads to a relative hypotony, presumably related to decreased aqueous humor production. Histopathologic study has demonstrated ciliary body atrophy on an ischemic basis. The authors used ultrasound biomicroscopy to demonstrate in vivo the hypotrophic condition of the ciliary body in ocular ischemic syndrome.