BASICS

DESCRIPTION

• The central retinal artery exits the optic nerve to provide blood supply to the inner retinal layers.

• Occlusion of either the central retinal artery or one of its branches leads to acute, painless, monocular vision loss.

RISK FACTORS

• Hypertension

• Diabetes mellitus

• Carotid artery atherosclerosis

• Cardiac valve disease

• Hypercoagulable states

PATHOPHYSIOLOGY

Loss of perfusion leads to retinal ischemia and infarction in the associated vascular territory.

ETIOLOGY

• Embolus.

– Types of emboli:

– Cholesterol emboli (hollenhorst plaque) – yellow and refractile

– Platelet-fibrin emboli – chalky white

– Calcium emboli (often from cardiac valves)

– Fat emboli

– Cardiac myxoma

– Septic emboli (from endocarditis)

– Talc emboli (intravenous drug users)

• Intravascular thrombosis: For CRAO, usually it occurs at the lamina cribrosa of the optic nerve.

• Vasculitis. Giant cell arteritis accounts for 1–2% of cases of CRAO.

• Other collagen vascular disease includes systemic lupus erythematosus, polyarteritis nodosa, Wegener’s granulomatosis.

• Vasospasm

• Dissecting aneurysm

• Trauma

• Hypercoagulable states: Antiphospholipid antibody syndrome, oral contraceptive use, polycythemia

• Syphilis

• Behçet’s syndrome

• Sickle cell anemia

DIAGNOSIS

HISTORY

• Acute, painless, monocular vision loss

• BRAO may present with loss of vision, a scotoma, visual field deficit, or may be asymptomatic.

• CRAO typically causes profound vision loss.

• There are chances of possible history of preceding transient vision loss.

• In patients over 50 years old, headache, jaw claudication, scalp tenderness, or fatigue may suggest giant cell arteritis.

PHYSICAL EXAM

• Blood pressure

• Listen for carotid bruit and cardiac murmurs

• For BRAO, visual acuity depends on the location of the obstruction, and may be normal.

• Approximately 90% of eyes with CRAO have visual acuity between count fingers and light perception (1).

• Approximately 25% of eyes with CRAO have a patent cilioretinal artery, which arises from the choroidal circulation. This may lead to macular sparing and resultant preservation of some visual function (2).

• Relative afferent pupillary defect is often present, especially with CRAO.

• For CRAO: Whitening and opacification of the inner retina in the posterior pole with a cherry red spot in the central macula

• For BRAO: Whitening and opacification of the inner retina in the vascular territory affected. Cotton wool spots may also be seen

• Embolic material may be present in retinal arterioles.

• Retinal vessels may appear poorly perfused, with “boxcarring” of the blood column.

DIAGNOSTIC TESTS & INTERPRETATION

Lab

• Complete blood count with platelets

• Erythrocyte sedimentation rate

• C-reactive protein

• Fibrinogen

• Lipid profile

• Fasting blood sugar

• Other tests in certain situations:

– Prothrombin time/activated partial thromboplastin time

– Rapid plasmin reagin

– Fluorescent treponemal antibody absorbed

– Antinuclear antibody

– Rheumatoid factor

– Serum protein electrophoresis

– Hemoglobin electrophoresis

– Antiphospholipid antibodies

– Homocysteine

– Hypercoagulable work-up in select situations

Imaging

Fluorescein angiography may reveal delayed arteriolar filling or delayed arteriovenous transit time.

Diagnostic Procedures/Other

• Carotid ultrasound

• Echocardiogram (consider trans-esophageal study)

• Electrocardiography

• Temporal artery biopsy if giant cell arteritis is suspected

• Visual field testing

DIFFERENTIAL DIAGNOSIS

Ophthalmic artery occlusion: Suspect if there is associated optic disc edema and in cases of light perception vision or worse.

TREATMENT

MEDICATION

First Line

• In general, treatment options for CRAO and BRAO are limited.

• Medication is prescribed to decrease intraocular pressure: Either topical drops or oral acetazolamide.

• If giant cell arteritis is suspected, systemic steroids is immediately started to decrease the risk of second eye involvement.

– Oral prednisone 1 mg/kg per day or intravenous methylprednisolone 250 mg per 6 h

Second Line

Consider aspirin

ADDITIONAL TREATMENT

Issues for Referral

Patients are referred to a primary care provider for complete medical evaluation and for vascular risk factor management.

SURGERY/OTHER PROCEDURES

• Anterior chamber paracentesis

• Ocular massage: In an attempt to dislodge embolus and move it downstream

• The role of thrombolytic agents in the management of CRAO is not clear (4).

ONGOING CARE

FOLLOW-UP RECOMMENDATIONS

• Repeat eye examination in 1–4 weeks.

– Assess for development of neovascularization of the iris. This may occur in approximately 20% of eyes with CRAO, usually after 4–5 weeks (3).

• Neovascularization of the optic disc or retina also occurs, although more rarely.

– If neovascularization develops, proceed with retinal panretinal photocoagulation.

– Consider intravitreal pharmacotherapy with antivascular endothelial growth factor agents.

Patient Monitoring

Monitor for worsening vision, development of eye pain (which could arise from neovascular glaucoma), and any visual changes in the contralateral eye.

PROGNOSIS

• Long-term visual prognosis for CRAO is poor.

• For BRAO, many eyes will recover visual acuity to the level of 20/40 or better.

COMPLICATIONS

• Neovascular glaucoma

• Other complications may occur from ocular neovascularization, such as vitreous hemorrhage.

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