Transient ischemic attacks are neurologic deficits lasting less than 24 hours and are reversible. The most common ophthalmologic TIA is amaurosis fugax, which is a fleeting monocular blindness caused by an embolic event. There is a sudden graying or reduction of vision, often moving from the peripheral vision to the center to cover the entire visual field within a few seconds. After 1 to 5 minutes, the central vision
begins to return first. Other causes of TIAs include chronic disc edema (in which vision loss lasts seconds, not minutes), chronic papilledema with bilateral blackouts based on optic nerve disease (often also lasting a few seconds and caused by postural changes), and basilar artery insufficiency. TIAs related to basilar artery insufficiency are usually bilateral blackouts lasting seconds or minutes, often with changes in the posterior circulation.
The most important mechanisms involving carotid TIAs with stroke are embolization from the carotid artery or its branches, reduced perfusion caused by carotid stenosis or occlusion, or a combination of the two. In most patients (up to 90%), the site of the obstruction is the carotid sinus. Hollenhorst plaques are bright-yellow cholesterol emboli that may occlude the retinal arterioles (see Fig. 41-10). Fibrin platelet emboli can occur near retinal arterioles and produce visual symptoms. A cholesterol or fibrin platelet embolus is indicative of ulcerative disease in the carotid arteries and is associated with a high incidence of ischemic heart disease, peripheral vascular disease, stroke, and aortic abdominal aneurysm. A rarer form of carotid TIA is related to valvular heart disease, particularly with a prolapsed mitral valve or
The complete reference list is available online at www.expertconsult.com.
American Association of Pediatric Ophthalmology and Strabismus; focuses on research and training in pediatric ophthalmology and the advanced care of adults with strabismus. www.ascrs.org
American Society of Cataract and Refractive Surgeons; provides clinical and practice management information to members.
cardiac arrhythmia. Approximately 30% to 50% of patients with TIAs and carotid artery disease have a major stroke within 1 month of the first attack.
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