Vascular Disorders

Vascular disorders that affect vision include central and branch retinal artery or vein occlusion, ischemic optic neuropathy, amaurosis fugax, occipital lobe stroke, and temporal arteritis (which occurs primarily in the elderly).

Atherosclerotic cardiovascular risk factors underlie almost all ophthalmic vascular disorders, and treatment focuses on management of these risk factors. The leading cause of death in patients with an ophthalmic vascular disorder is a cardiovascular disorder.

Retinal Artery Occlusion

Retinal artery occlusion causes painless, sudden, unilateral blindness.

The most common cause of retinal artery occlusion in the elderly is embolization of a thrombus or an atheroma from the carotid artery to the central retinal artery in the optic nerve head. Less common causes include temporal arteritis, optic neuritis, hypercoagulability, and, rarely, severely elevated intraocular pressure (IOP). Within an hour of occlusion, reactive arterial spasm ceases, and some blood flow is restored to the retina, which then appears relatively normal through an ophthalmoscope. However, within several hours the retina becomes edematous and gray because ischemia continues and retinal ganglion cells die. Because the retina in the foveal area contains no ganglion cells, the reddish underlying choroid remains visible, accounting for the characteristic, central, cherry-red spot surrounded by the gray retina. In 2 to 3 wk, the cherry-red spot disappears, and as the ganglion cells and their axons die, the optic nerve becomes white--the hallmark of primary optic atrophy.

A retinal artery branch may become occluded when an atheroma breaks off and passes through the central retinal artery. The occlusion (called a Hollenhorst plaque) can usually be seen as a refractile object in the branch. This finding indicates embolic activity, usually originating in the carotid system. The portion of the retina supplied by the occluded vessel stops functioning, resulting in a visual field defect that may not affect central vision.

Intervention is rarely possible because it is needed within 90 min of the occlusion to prevent retinal cell death. Rapidly reducing IOP by paracentesis plus vasodilators occasionally induces the embolus to move more peripherally, limiting vision loss in the affected area. Other treatments (eg, eyeball massage to improve O₂ delivery to tissues, CO₂ therapy to promote vasodilation, oral anticoagulants, thrombolytics) may be attempted. None has proved effective, and thrombolytics may have serious adverse effects. Patients should also be evaluated for atherosclerotic risk factors, which should be managed. Anticoagulants may help decrease risk of future emboli.

Retinal Vein Occlusion

Retinal vein occlusion causes painless, sudden, usually unilateral blindness.

Retinal vein occlusion (RVO) is probably the most common ophthalmic vascular disorder and occurs most commonly among people with atherosclerosis or glaucoma. Less common causes include leukemia and lymphoma, autoimmune disorders, and hypercoagulability disorders. RVO is classified as nonischemic or ischemic and may affect the central retinal vein or a branch.

Central RVO: Symptoms are similar to those of central retinal artery occlusion--sudden, painless, typically severe, unilateral vision loss. After central RVO occurs, some minimal vision may remain. About 10% of patients who develop central RVO in one eye later develop central RVO in the other eye.

Diagnosis is by ophthalmoscopy. Findings include distended, tortuous veins with massive hemorrhages and edema throughout the retina. The margins of the optic nerve become blurred, and the disk becomes swollen. Complete resorption of the hemorrhages and edema may take months or even years.

Fluorescein angiography helps differentiate nonischemic from ischemic forms. Ischemic RVO is characterized by relatively large retinal areas of capillary nonperfusion (which may require retinal laser photocoagulation if neovascularization occurs).

Prognosis is poor for elderly patients. About 25% develop a fibrovascular membrane that seals the aqueous humor outflow channels in the anterior chamber, resulting in a painful, secondary neovascular glaucoma in 3 to 6 mo; without treatment, blindness occurs within weeks. Patients with the nonischemic form have a better visual prognosis than those with the ischemic form.

Central RVO is most often treated with retinal laser photocoagulation, but its effectiveness is still being assessed. Systemic anticoagulation is not typically recommended. Intravitreal injection of triamcinolone acetonide may help decrease macular edema and improve visual acuity in some patients with central RVO.

Branch RVO: This disorder is similar to central RVO, but a branch of the central retinal vein is obstructed, most often the superior temporal branch. Vision is usually unaffected unless the retinal swelling impinges on the macula. Visual field defects, if present, depend on which retinal quadrant is involved. Neovascular glaucoma develops much less often in branch RVO than in central RVO.

Diagnosis is similar to that for central RVO. Ophthalmoscopic findings include exudates and hemorrhages confined to the involved retinal quadrant. Laser photocoagulation helps preserve vision.

Ischemic Optic Neuropathy

Ischemic optic neuropathy is inadequate blood supply to the optic nerve, sometimes causing blindness.

Ischemic optic neuropathy (ION) usually occurs only in people > 60. Most cases are nonarteritic and attributed to the effects of atherosclerosis, diabetes, or hypertension on optic nerve perfusion. Temporal arteritis causes about 5% of cases (arteritic ION).

Symptoms and signs are sudden, partial or complete vision loss, accompanied by swelling of the optic nerve head and often hemorrhage. Visual field defects may manifest as loss of half the visual field with a horizontal demarcation or as central or centrocecal (surrounding the natural blind spot) scotomata. Decreased vision is soon followed by pallor of the optic disk. When temporal arteritis is the cause, tenderness along the temporal artery may be noted, as well as headache, jaw pain while chewing, fever, malaise, anorexia, weight loss, and joint and muscle pain.

Diagnosis of nonarteritic ION is presumptive based on symptoms, signs, and presence of atherosclerotic risk factors. Diagnosis of arteritic ION is suggested by symptoms and signs and supported by a dramatically elevated Westergren ESR (normal: <= [age + 10]/2 for women and age/2 for men), an elevated C-reactive protein level, or both. Diagnosis is confirmed by temporal artery biopsy showing granulomatous inflammatory changes.

For nonarteritic ION, treatment does not help, but atherosclerotic risk factors should be managed. Most patients have at least some return of vision. Vision loss in the other eye may occur months or years later.

For arteritic ION, treatment is IV methylprednisolone (1 g/day for the first 3 to 5 days), after which oral prednisone (60 mg/day) can be used and tapered slowly over 3 to 12 mo or more, depending on response. Corticosteroids should be started immediately to protect the other eye; treatment should not be postponed for confirmation by biopsy. Long-term anticoagulant therapy may help selected elderly patients with a history of amaurosis fugax suggesting atheromatosis.

Amaurosis Fugax

Amaurosis fugax is acute vision loss lasting minutes to hours. It usually involves only part of a visual field of one eye.

Amaurosis fugax is a symptom that suggests retinal or optic nerve ischemia caused by atherosclerosis or an embolus in a carotid or thoracic aortic artery; this symptom occasionally indicates migraine headache. Patients > 50 are most susceptible. Risk factors are those for atherosclerosis and a family history of stroke.

Amaurosis fugax manifests as a dimming of vision in one eye, sometimes perceived as a window shade being partially or completely drawn over the eye. Recovery of clear vision begins within 5 to 10 min and occurs in the reverse order from the onset pattern. Several episodes may precede an attack of ischemic optic neuropathy or stroke. The annual risk of stroke after amaurosis fugax is about 2%. Amaurosis fugax can be bilateral if associated with low BP.

If amaurosis fugax is accompanied by hemiplegia on the side opposite the affected eye (indicating a transient ischemic attack), carotid stenosis on the side of the affected eye should be strongly suspected. Early recognition of severe carotid stenosis is important because without appropriate medical (eg, daily aspirin) and surgical (eg, carotid endarterectomy) intervention, permanent vision loss or hemiplegia often results. Aortic arch syndrome may be suspected if blackouts become increasingly frequent and are related to changes in posture (eg, suddenly sitting up or standing).

Occipital Lobe Stroke

Occipital lobe stroke is caused by a vascular lesion in the vertebral-basilar system and causes sudden, sometimes total blindness.

Infarction in one or both occipital lobes may result from local atheromas or emboli in the vertebral-basilar system. An occipital lobe stroke, usually resulting from posterior cerebral artery infarction, is characterized by sudden onset of congruous homonymous hemianopia. Total blindness occurs suddenly; however, within minutes, some vision returns in the ipsilateral homonymous visual field. Bilateral posterior occlusions usually occur simultaneously. Thrombosis of the basilar artery also causes bilateral homonymous hemianopia.

As with any ischemic stroke, treatment with aspirin or other anticoagulants is indicated. Some vision returns in almost all patients with cortical blindness.

This topic was last updated May 2006.