BASICS

DESCRIPTION

• Ocular ischemic syndrome (OIS) refers to anterior and posterior segment signs and symptoms related to chronic ocular hypoperfusion.

• Most common cause is severe carotid occlusive disease.

• The most common symptoms are monocular visual loss and ocular/orbital pain.

• Patients are also at increased risk for cerebral and myocardial infarction.

EPIDEMIOLOGY

Incidence

• Relatively uncommon but probably underdiagnosed

• Estimated at 7.5 cases per million per year

RISK FACTORS

• Males > females 2:1 (atherosclerotic disease)

• Older age: mean 65 years, range 50–80 years

• No racial predilection

• Bilateral involvement in up to 22% of cases

PATHOPHYSIOLOGY

• Decreased vascular perfusion in the presence of poor collateral circulation leads to hypoperfusion of ocular tissues.

• Ischemia and subsequent neovascularization produce ocular signs and symptoms.

ETIOLOGY

• Reduced blood flow to the eye/orbit

– Most common is severe atherosclerotic disease of carotid vascular system (generally ≥90% stenosis), with internal > common > external carotid.

– 5% lifetime risk for patients with internal carotid artery (ICA) stenosis to develop OIS

– Less common: ophthalmic artery disease, systemic vasculitis (giant cell arteritis [GCA]), vaso-occlusive disease (i.e., aortic arch syndrome), Takayasu arteritis

COMMONLY ASSOCIATED CONDITIONS

• Systemic vascular disease

– Systemic arterial hypertension (HTN)

– Diabetes mellitus (DM)

– Coronary artery disease (CAD)

– Previous cerebrovascular accident or transient ischemic attack

– Peripheral vascular disease

DIAGNOSIS

HISTORY

• Loss of vision

– Most frequent symptom; present in 70% or above at presentation, absent in less than or equal to 10%

– Variable in severity and onset—more than 2/3 are less than 20/60 at presentation; most experience vision loss over weeks to months, although some have abrupt vision loss

• Pain—40% present with pain due to increased intraocular pressure (IOP) or ischemia (“ocular angina”—dull, constant ache over the brow)

• Transient vision loss/amaurosis fugax

– Present in 10–15% of patients

• Afterimages or prolonged recovery of vision after light exposure

PHYSICAL EXAM

• Anterior segment

– Conjunctival and episcleral injection

– Corneal edema and/or Descemet’s folds

– Iris atrophy and neovascularization (66%)

– Anterior and posterior synechiae

– Fixed and semidilated pupil or afferent pupil defect (APD)

– Mild iritis in 20% (flare > cell)

– Cataract

– Neovascular glaucoma in 1/3 of patients

– IOP may be low/normal second to decreased ciliary body perfusion.

– Hypotony can further exacerbate corneal decompensation, cataract, and maculopathy.

• Posterior segment (more frequent)

– Narrowed retinal arteries

– Veins dilated but not tortuous

– Retinal hemorrhages in 80% of patients, mostly dot-blot and in midperipheral retina

– Microaneurysms common in midperipheral retina; more visible on fluorescein angiogram

– Spontaneous retinal arterial pulsations

– Cherry-red spot (12%) from embolic or increased IOP induced occlusion of central retinal artery

– Cotton–wool spots (6%)

– Choroidal ischemia and peripheral wedge-shaped chorioretinal atrophy

– Neovascularization of disc (NVD) in 35%, neovascularization elsewhere (NVE) in 10%

• Orbital infarction syndrome

– Ischemia of intraocular and intraorbital contents

– Corneal hypoesthesia, intraocular inflammation, hypotony, ophthalmoplegia, ptosis, proptosis, orbital pain

• Systemic exam

– Pulses, carotid and cardiac auscultation

DIAGNOSTIC TESTS & INTERPRETATION

Lab

Initial lab tests

• Fluorescein angiography (FA)

– Delayed or patchy choroidal filling in 60% of patients; most specific FA sign

– Prolonged arteriovenous transit time in up to 95% of patients; most sensitive

– Staining of retinal vessels in 85%; arterial more than venous staining

– Leading edge of arterial dye

– 15% with macular edema (noncystoid pattern), often with disc leakage

– Retinal capillary nonperfusion

• Consider ESR or C-reactive protein (CRP) if suspected GCA

Follow-up & special considerations

• Indocyanine green angiography (ICG)

– Prolonged arm–choroid time; slow intrachoroidal filling time; and watershed zone filling

Imaging

Initial approach

• Carotid Doppler ultrasound

– Most commonly used noninvasive test shows anatomy and hemodynamics.

– Reduced peak systolic velocity and increased vascular resistance of end arteries

– May be limited by complex anatomy, large plaque, calcific shadows, or tortuous vessels

– Operator and machine dependent

Follow-up & special considerations

• Retrobulbar vessel Doppler

– May show reversal of ophthalmic artery flow, a highly specific indicator of high-grade ICA stenosis or occlusion

• Magnetic resonance angiography

– Noninvasive; evaluates anatomy of intracranial vessels and very accurate

– Limits include claustrophobia, pacemaker, metallic stents, and obesity.

• Carotid angiography

– Gold standard for imaging cerebrovascular system, but expensive and invasive (risk for cerebral infarction)

– Perform if surgery a consideration

Diagnostic Procedures/Other

• Electroretinography (ERG)

– Ischemia of outer and inner retina with decreased amplitude of a and b waves

• Visual-evoked potentials (VEP)

– Increased latency, decreased amplitude

• Ophthalmodynamometry

– Decreased ophthalmic and central retinal artery pressure

Pathological Findings

Loss of endothelial cells and pericytes in peripheral retinal vessels can lead to vessel leakage.

DIFFERENTIAL DIAGNOSIS

• Central retinal vein occlusion (CRVO)

– Dilated and tortuous retinal veins (due to outflow obstruction in CRVO vs. decreased inflow in OIS)

– Flame-shaped (more superficial) hemorrhages in all 4 quadrants

– Swollen optic nerve

– Macular edema is common.

• Diabetic retinopathy

– Always bilateral, usually symmetric

– Microaneurysms and dot-blot hemorrhages common in posterior pole as well as midperipheral retina

– Hard exudates common

– Rare diabetic papillopathy

TREATMENT

Goal is to treat the underlying problem (ocular hypoperfusion) and associated ocular complications.

MEDICATION

First Line

• Topical treatment (1)[B]

– Steroids—reduce inflammation

– Cycloplegia—stabilize blood–aqueous border

– IOP-lowering agents that reduce aqueous outflow (beta-blockers, alpha-agonists, or carbonic anhydrase inhibitors)

– Avoid pilocarpine and prostaglandins (may increase inflammation)

• Intravitreal injections (2)[C]

– Anti–vascular endothelial growth factor (VEGF) and steroids can be considered to treat macular edema.

– Anti-VEGF may help with neovascularization.

Second Line

• Panretinal photocoagulation can cause regression of NVD, neovascularization of the iris (NVI), and NVE in 1/3 of cases and can reduce risk of neovascular glaucoma (NVG).

• NVG is often refractory to medical treatment and may require surgery with trabeculectomy, tube shunt, or cycloablation if poor visual prognosis.

ADDITIONAL TREATMENT

General Measures

• Systemic disease must be treated as patients have high risk of vascular death.

– Treatment of systemic disease: HTN, DM, dyslipidemia, CAD

– Antiplatelet therapy

– Lifestyle modification: smoking cessation, healthy diet, weight loss

Issues for Referral

• All patients with OIS should have medical workup by primary care physician.

• Consider consultations from cardiology and neurosurgery.

Additional Therapies

Thrombolytic therapy can be considered in appropriate patients

SURGERY/OTHER PROCEDURES

• Carotid endarterectomy (CEA) (3)[A]

– CEA and aspirin superior to aspirin alone in preventing stroke in patients with symptomatic/asymptomatic carotid stenosis

– CEA for symptomatic stenosis of 50–99% if risk of stroke/death is less than 6%

– CEA for asymptomatic stenosis of 60–99% if risk of stroke/death is less than 3%

– Effect on visual outcome inconclusive: more beneficial if CEA performed before development of NVG

• Carotid artery stenting

– Alternative in patients with difficult anatomy or medical conditions that preclude CEA

• Extraintracranial bypass surgery

– Consider if complete occlusion of ICA or common carotid artery (CCA)

ONGOING CARE

DIET

Low-fat, low-salt, low-sugar diet given other systemic conditions

PROGNOSIS

• Overall visual prognosis is poor.

– Visual acuity at presentation is an important predictor of final outcomes.

– Iris neovascularization at presentation associated with poor visual outcome—97% of these eyes have final visual acuity (VA) less than finger counting

• Systemic outcomes

– Mortality rate 40% at 5 years

– Cardiovascular disease (myocardial infarction [MI]) accounts of 2/3 for deaths.

– Cerebral infarcts cause 19% of deaths.

– Cancer is the 3rd leading cause.

– Mortality rate is 11% in age- and sex-matched controls.

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