central retinal artery occlusion

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central retinal artery occlusion

Abbreviation: CRAO
Blockage of blood flow to the retina (that is, to the central retinal artery or one of its branches), resulting in sudden visual loss. The condition usually affects one eye. When the retinal artery is blocked by a blood clot, early thrombolysis sometimes provides sight-preserving therapy.


CRAO is typically caused by a tiny embolus that lodges in the retinal circulation. It usually occurs in people with high blood pressure, diabetes mellitus, cardiac valve disease, or atrial fibrillation, which predispose to atherosclerosis or arterial embolization. Other causes include inflammatory or autoimmune diseases affecting the circulation (arteritis), clotting disorders, hyperlipidemia, injected drugs or contaminants, and tumor metastases.

See also: occlusion

retinal arterial occlusion 

Occlusion of the central retinal artery (CRAO) is characterized by a sudden loss of vision and a defective direct pupil light reflex. The retinal arterioles are constricted while the veins are full but a venous pulse is absent. The retina appears white and swollen, especially near the posterior pole, and the choroid is seen through it as a cherry-red spot (Fig. S12). If the occlusion persists the cherry-red spot disappears after several weeks, the retinal arterioles remain attenuated, eventually becoming white threads, and the optic disc becomes atrophic.Occlusion is more frequently limited to one branch of the central retinal artery (BRAO). In this case, the clinical picture is limited to the area supplied by the branch and this is associated with a visual field defect in that region. Causes include retinal emboli due to a cardiovascular disease, systemic hypertension, temporal arteritis, oral contraceptives, syphilis, intravenous drug abuse or trauma. Treatment is urgent as there is an extremely serious risk of blindness. See amaurosis fugax; fluorescein angiography; atheroma; Hollenhorst's plaques; cherry-red spot.
Fig. S12 Cherry-red spot at the maculaenlarge picture
Fig. S12  Cherry-red spot at the macula
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