Occlusion of the posterior ciliary artery. II. Chorio-retinal lesions.

The clinical picture of central retinal artery occlusion is well-known. Little is known, however, about the clinical picture of occlusion of the posterior ciliary arteries (PCAs). We have, therefore, carried out experimental occlusion of the various PCAs individually or together in rhesus monkeys. The effects of such occlusions have been investigated in the choroid, pigment epithelium (PE), and retina of these monkeys over a period of time, ophthalmoscopically, by intravenous fluorescence fundus angiography (IVFA), and (after death) by histology. The study has revealed fundus lesions the nature of which has hitherto been obscure. There are usually two to three PCAs, arising from the ophthalmic artery, which supply the posterior half of the choroid up to the equator of the eye. These are designated medial (MPCA) and lateral (LPCA), depending upon their relationship to the optic nerve near their site of entry into the sclera. A detailed account of the anatomy of the PCAs is given elsewhere (Hayreh, i962, 1970). The effects of occlusion of the various PCAs on the choroidal circulation have already been described in detail (Hayreh and Baines, 1972). Briefly, the distribution of the PCAs in the choroid was seen to be segmental, so that occlusion of one PCA resulted in nonperfusion of the choroid in that region during the transit of the dye in IVFA. However, a very late and sluggish patchy filling of the choroid via the various collaterals took place; this improved with time, so that in 2 to 4 weeks the choroidal circulation was restored.