Posterior Ciliary Artery Occlusion.

Objective: To compare the severity of ischemic damage following posterior ciliary artery (PCA) occlusion in old, atherosclerotic, hypertensive monkeys to that in young monkeys.

Design: Experimental study.

Subjects: Seven eyes of normal, healthy rhesus monkeys and 8 of old, atherosclerotic, hypertensive monkeys.

Methods: By lateral orbitotomy, all PCAs were cut behind the eyeball in both groups of animals. The fundus and the optic disc were evaluated by repeated ophthalmoscopy, color fundus photography and fluorescein fundus angiography, before and immediately after cutting the PCAs and serially thereafter during the follow-up period.

Main Outcome Measures: Severity of acute ischemic damage to the choroidal, outer retinal and optic nerve head.

Results: Cutting all the PCAs resulted in the development of ischemic infarction of the choroid, retinal pigment epithelium, outer part of the retina and the optic nerve head within 24-hours, in both groups of animals. The severity of the various ischemic fundus and retinal lesions and of the optic disc during the acute phase showed no statistically significant differences between the two groups of animals. Fluorescein fundus angiography soon after cutting the PCAs showed no filling of the entire choroid and the optic disc in both groups of animals. On follow-up for up to about 3 months, in both groups, the white opacity of the infract in the fundus seen during the acute phase gradually resolved in about 2-3 weeks, leaving greyish, granular, depigmented fundus, unmasking of the large choroidal vessels and optic atrophy; fluorescein angiography revealed gradual restoration of the choroidal blood flow and unmasking of the big choroidal vessels.

Conclusions: The study showed that the severity of ischemic damage following occlusion of all the PCAs was similar in both the young healthy and the old, atherosclerotic, hypertensive monkeys. This is in contrast to the findings of our similar study dealing with central retinal artery occlusion, where the young suffered much severe ischemic damage than the old.