Branch Retinal Artery Occlusion
Although an acute BRAO may be subtle and unapparent on initial ophthalmoscopic examination, within hours to days, it can lead to edematous opacification caused by infarction of the inner retina in the distribution of the affected vessel (Fig 6-16). In time, the occluded vessel recanalizes, perfusion returns, and the edema resolves; however, a permanent visual field defect remains. A retinal arterial occlusion that occurs outside of the posterior pole may be clinically asymptomatic.
Occlusion at any site is caused by embolization or thrombosis of the affected vessel. There are 3 main varieties of emboli:
-
cholesterol emboli (Hollenhorst plaques) arising in the carotid arteries (Fig 6-17)
-
platelet-fibrin emboli associated with large-vessel arteriosclerosis
-
calcific emboli arising from diseased cardiac valves
In rare cases, emboli might be caused by cardiac myxoma, long-bone fractures (fat emboli), infective endocarditis (septic emboli), and intravenous drug use (talc emboli). Although rare, migraine can cause ocular arterial occlusions in patients younger than 30–40 years. Other possible causes of emboli include
-
arrhythmias
-
mitral valve prolapse
-
oral contraceptive use or pregnancy
-
coagulation disorders
-
trauma
-
sickle cell disease
-
inflammatory and infectious etiologies such as toxoplasmic retinochoroiditis and syphilis
-
connective tissue disorders, including GCA
Initial management is directed toward determining the underlying systemic etiologic factors. Retinal arterial occlusions should be referred urgently to an emergency department for a stroke workup. No specific ocular therapy has been found to be consistently effective in improving the visual prognosis. Lowering IOP and applying intermittent pressure on the globe (“ocular massage”) may dislodge an embolus from a large central vessel toward a more peripheral location, but the efficacy of these maneuvers in improving vision outcomes is unknown.
-
Hayreh SS, Podhajsky PA, Zimmerman MB. Branch retinal artery occlusion: natural history of visual outcome. Ophthalmology. 2009;116(6):1188–1194.
-
Wang JJ, Cugati S, Knudtson MD, et al. Retinal arteriolar emboli and long-term mortality: pooled data analysis from two older populations. Stroke. 2006;37(7):1833–1836.
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.