Retina and Optic Nerve After Posterior Ciliary Artery Occlusion:  An Experimental Study in Squirrel Monkeys

After experimental occlusion of the posterior ciliary arteries in one eye of squirrel monkeys, retinal pigment epithelial atrophy occurred in geographic patches, but much of the retinal area, especially in the peripapillary region, remained normal. Only minute areas of atrophy occurred in the optic nerve head, presumably because of protection afforded by anastomotic connection to the vessels of the pia mater and retina. Assuming that circulatory dynamics of monkeys and humans are similar, ischemic papillitis must represent disease of more than just the posterior ciliary arteries. In glaucomatous cupping, intraocular pressure may affect circulation by capillary or venous compression, but there has been undue emphasis on the fact that the short posterior ciliary arteries supply the disc, as well as unwarranted assumptions that the responses of the optic disc blood flow can be predicted from studies of choroidal circulation.