In a smoker with hypertension who presents with sudden painless loss of vision in one eye, what is the most likely diagnosis and what emergent management should be initiated?

Sudden Painless Monocular Vision Loss in a Smoker with Hypertension

This patient most likely has central retinal artery occlusion (CRAO), an acute ischemic stroke equivalent that requires immediate emergency department transfer to a stroke center for potential thrombolytic therapy within 4.5 hours. 1

Most Likely Diagnosis: Central Retinal Artery Occlusion

CRAO is the primary diagnosis because sudden, painless monocular vision loss occurring over seconds is the hallmark presentation, and this patient's risk factor profile—smoking, hypertension—directly matches the epidemiologic pattern where CRAO incidence increases dramatically with vascular risk factors including hypertension, hyperlipidemia, diabetes, and tobacco exposure. 1, 2

Key Diagnostic Features Supporting CRAO

• Sudden onset over seconds (not hours or days) distinguishes CRAO from retinal detachment, which presents as a progressive "curtain" developing over hours, and from optic neuritis, which evolves over hours to days. 1, 3, 2

• Painless presentation effectively excludes acute angle-closure glaucoma (which causes severe ocular pain, headache, and nausea) and optic neuritis (which typically causes pain with eye movement). 1, 4

• Thromboembolic pathophysiology accounts for 95% of CRAO cases, driven by embolic occlusion from the ipsilateral internal carotid artery, aortic arch, or heart—all directly linked to smoking and hypertension. 1

Expected Examination Findings

• Relative afferent pupillary defect (RAPD) will be present unless there is contralateral optic neuropathy. 1, 2

• Funduscopic examination reveals retinal whitening (from ischemic nerve fiber layer edema), cherry red spot at the fovea (normal choroidal perfusion visible through the fovea which lacks nerve fiber layers), attenuated retinal arteries, and "boxcar" segmentation of blood flow in retinal vessels. 1, 2

• Visual acuity is typically "count fingers" or worse in over 80% of cases. 1, 2

Emergent Management Protocol

Immediate Actions (Within Minutes)

Transfer to the nearest stroke center immediately—CRAO is now formally recognized as an acute ischemic stroke equivalent by the American Heart Association, requiring stroke protocol activation. 1, 2

Do not delay transfer for ophthalmologic consultation or funduscopic examination in the office—eye care providers should serve as "gate-keepers" for rapid diagnosis, then immediately refer to a stroke center without attempting further testing. 5

Thrombolytic Therapy Considerations (Within 4.5 Hours)

• Intravenous tPA may be considered in patients with disabling visual deficits who otherwise meet criteria for systemic tPA, after thorough benefit/risk discussion with the patient. 1

• Intra-arterial tPA may be considered at centers capable of deploying endovascular therapy, especially in patients not eligible for intravenous tPA, though this remains an unproven therapy justified only by the devastating natural history of CRAO. 1

• Conservative treatments are NOT recommended—there is no compelling evidence that ocular massage, anterior chamber paracentesis, or hemodilution are effective, and observational literature suggests these may be harmful. 1

Critical Time-Sensitive Stroke Workup (Within 24 Hours)

• Brain MRI with diffusion-weighted imaging identifies concurrent acute brain infarction, present in 20-24% of CRAO patients. 5, 2

• Vascular imaging (CTA or MRA) assesses for carotid stenosis—up to 70% of CRAO patients have significant ipsilateral carotid plaque, and 18% have >80% stenosis. 1, 5

• Cardiac monitoring and echocardiography evaluates for cardioembolic sources including atrial fibrillation. 1

• Stroke risk remains highest in the first 7 days, with 3-6% risk of concurrent or subsequent cerebral stroke within 1-4 weeks—never assume reperfusion eliminates stroke risk. 5, 2

Mandatory Giant Cell Arteritis (GCA) Evaluation

All patients ≥50 years with sudden monocular vision loss require urgent GCA assessment, as 5% of CRAOs are arteritic, usually from giant cell arteritis. 1, 5

Immediate GCA Protocol

• Obtain ESR and CRP immediately without delaying treatment—do not await laboratory results before initiating therapy if clinical suspicion is high. 5

• Start high-dose corticosteroids immediately if GCA is suspected, prior to biopsy or imaging confirmation, to prevent involvement of the contralateral eye—delaying corticosteroid therapy is the strongest predictor of permanent blindness. 5

• Screen for GCA clinical features: new-onset temporal headache, jaw claudication (most specific symptom), scalp tenderness, constitutional symptoms (≥2 kg weight loss, fever, fatigue), and polymyalgia rheumatica symptoms (proximal muscle stiffness). 5, 4

• Arrange urgent specialist referral within 24 hours for temporal artery biopsy and vascular imaging (temporal artery ultrasound or MRI). 5

Differential Diagnosis Exclusions

Branch Retinal Artery Occlusion (BRAO)

• Excluded because BRAO causes sectoral (not complete) visual field loss corresponding to the affected arterial distribution, not total monocular vision loss. 5, 2

Retinal Detachment

• Excluded because retinal detachment presents as a progressive "curtain" or dark shadow moving from peripheral to central visual field over hours (e.g., three hours), not seconds—this time course effectively excludes CRAO. 3

Retinal Vein Occlusion

• Excluded because retinal vein occlusion presents with diffuse intraretinal hemorrhages and venous tortuosity/dilation on fundoscopy, not the pale retina with cherry red spot of arterial occlusion, and typically has better initial visual acuity. 1, 5

Optic Neuritis

• Excluded because optic neuritis typically presents with pain on eye movement, occurs in younger patients (20-40s), and has gradual vision loss over hours to days rather than seconds. 2, 4

Migraine Visual Aura

• Excluded because migraine auras are transient (5-60 minutes), feature positive visual phenomena (scintillations, zigzag lines), and resolve completely without permanent vision loss. 3, 2

Prognosis and Secondary Prevention

Natural History Without Intervention

The natural history of CRAO is devastating—only 17% of patients achieve functional visual acuity in the affected eye, with CRAO affecting central vision, peripheral vision, color vision, and stereovision. 1, 2

Long-Term Secondary Prevention

• Antiplatelet therapy is reasonable when the cause is cryptogenic or attributed to atherosclerosis. 1

• Anticoagulation may be appropriate if atrial fibrillation or another cardioembolic source is detected during workup. 1

• Carotid endarterectomy or stenting may be required for severe carotid stenosis for secondary stroke prevention. 1

• Aggressive vascular risk factor modification including smoking cessation, hypertension control, and management of hyperlipidemia and diabetes through both pharmacological and lifestyle interventions. 1

Critical Pitfalls to Avoid

Do not mistake CRAO for a purely ophthalmologic problem—it is a stroke equivalent requiring neurologic and cardiovascular evaluation, not just ophthalmologic management. 1, 2

Do not delay transfer for in-office testing—immediate stroke center transfer takes priority over funduscopic examination or point-of-care ultrasound in the primary care setting. 5, 6

Do not overlook GCA in patients ≥50 years—failure to initiate empiric steroids when GCA is suspected is the strongest predictor of bilateral blindness. 5, 4

Do not attempt conservative treatments—ocular massage and anterior chamber paracentesis lack evidence and may cause harm. 1