Acute retinal arterial ischemia, including central and branch retinal artery occlusion, is a true ocular and medical emergency. In patients 50 years of age or older with central retinal artery occlusion, giant cell arteritis must be considered (see Ischemic Optic Neuropathy and Chapter 20). Otherwise, even if no retinal emboli are identified on ophthalmoscopy, urgent investigation for carotid and cardiac sources of emboli must be undertaken in central and branch retinal artery occlusion so that timely treatment can be given to reduce the risk of stroke (see Chapters 12, 14, and 24). Diabetes mellitus, hyperlipidemia, and systemic hypertension are common etiologic factors. Migraine, oral contraceptives, systemic vasculitis, congenital or acquired thrombophilia, and hyperhomocysteinemia are also causes, particularly in young patients. Internal carotid artery dissection should be considered, especially when there is neck pain or a recent history of neck trauma. Multiple branch retinal artery occlusions, which may be asymptomatic, along with encephalopathy and hearing loss are the characteristic features of Susac syndrome.
Central retinal artery occlusion presents as sudden profound monocular visual loss. Visual acuity is usually reduced to counting fingers or worse, and visual field may be restricted to an island of vision in the temporal field. Ophthalmoscopy reveals pale swelling of the retina with a cherry-red spot at the fovea (Figure 7–2). The retinal arteries are attenuated, and "box-car" segmentation of blood in the arteries or veins may be seen as the RBCs separate from serum when blood flow is slowed or arrested. Occasionally, emboli are seen in the central retinal artery or its branches. The retinal swelling subsides over a period of 4–6 weeks, leaving a pale optic disk with thinning of the inner retina on optical coherence tomography scans; these findings can help diagnose unexplained vision loss if the patient is not examined during the acute occlusive event.
Branch retinal artery occlusion may also present with sudden loss of vision if the fovea is involved, but more commonly sudden loss of a discrete area in the visual field in one eye is the presenting complaint. Fundus signs of retinal swelling and sometimes adjacent cotton-wool spots are limited to the area of retina supplied by the occluded artery (eFigure 7–51).
Fluorescein angiogram of branch retinal artery occlusion of right eye showing non-perfused superior temporal branch retinal artery (outline arrow) and non-perfused retina (solid arrow), with microvascular changes at the border of perfused and nonperfused retina. (Used, with permission, from S Kiss and Optos plc.)
The clinician should identify risk factors for cardiac sources of ...