What is an ophthalmic (eye) stroke?

What is an Ophthalmic Stroke?

An ophthalmic stroke (also called "ocular stroke" or retinal artery occlusion) is a sudden blockage of blood flow to the eye that causes acute, painless vision loss and represents a medical emergency requiring immediate stroke center evaluation. 1

Definition and Pathophysiology

An ophthalmic stroke occurs when arterial blood supply to the retina or optic nerve is interrupted, causing ischemia and cell death in the affected ocular tissues. 1 The central nervous system defines this as retinal cell death attributable to ischemia, based on clinical evidence of permanent injury. 1

The retina has a dual blood supply: the inner retinal layers are supplied by the retinal arteries (branches of the ophthalmic artery), while the outer layers receive blood from the choroidal vessels. 2 When blood flow is blocked, the inner retinal layers become ischemic, leading to the characteristic clinical findings. 2

Types of Ophthalmic Stroke

Central Retinal Artery Occlusion (CRAO)

• Complete blockage of the central retinal artery causing profound vision loss (typically "counting fingers" or worse in >80% of patients) 2
• Presents with the classic "cherry-red spot" at the macula on fundoscopic examination 1, 2
• The American Heart Association considers CRAO a stroke equivalent requiring immediate stroke center evaluation 3

Branch Retinal Artery Occlusion (BRAO)

• Blockage of a branch of the retinal artery causing sectoral vision loss 3
• Results in partial visual field defects rather than complete vision loss 4

Ophthalmic Artery Occlusion (OAO)

• Blockage of the main ophthalmic artery affecting both inner and outer retinal layers plus the optic disc 2
• Poor choroidal circulation visible on specialized imaging 1

Common Causes

Embolic (Most Common)

• Vascular emboli from carotid artery disease, cardiac valve disease, or atrial fibrillation 2, 3
• Visible retinal emboli may be seen on examination with characteristic "boxcarring" of retinal vessels 1
• Up to 70% of CRAO patients have newly discovered significant cardiovascular conditions, typically clinically significant carotid stenosis 1, 3

Giant Cell Arteritis (Critical to Identify)

• The most common non-embolic cause, particularly in patients over 50 years old 2
• Causes inflammatory vessel wall thickening and occlusion 2
• This represents an ophthalmologic emergency requiring immediate high-dose corticosteroids to prevent vision loss in the fellow eye 1, 3
• Associated symptoms include temporal tenderness, jaw claudication, headaches, scalp tenderness, weight loss, fever, and polymyalgia rheumatica 1, 2

Other Causes

• Severe carotid stenosis causing hemodynamic impairment 2
• Vasculitis and other inflammatory systemic diseases 2
• Hypercoagulable states, antiphospholipid antibodies 1
• In younger patients: Susac syndrome (triad of hearing loss, CNS lesions, and BRAOs) 1

Clinical Presentation

Sudden, painless monocular vision loss is the hallmark presentation. 2, 3 The vision loss can be:

• Transient (lasting seconds to minutes): represents a retinal TIA called transient monocular vision loss (TMVL) 3
• Permanent: indicates completed infarction 2

Key Examination Findings

• Retinal edema and cherry-red spot at the macula 1, 2
• Narrowed retinal arteries 1
• Retinal vascular "boxcarring" (segmentation of blood flow) 1
• Visible retinal emboli 1
• Cotton wool spots and retinal hemorrhages 1, 2
• Relative afferent pupillary defect 1

Critical Time Window

Experimental studies demonstrate that retinal arteries can be occluded for up to 97 minutes without noticeable damage, while severe and irreversible damage occurs after 240 minutes. 2 This narrow therapeutic window makes immediate recognition and referral essential.

Why This is a Medical Emergency

High Stroke Risk

• The risk of cerebral stroke is 3-6% within the first 1-4 weeks after retinal artery occlusion 1
• Stroke risk is highest within the first 7 days and remains elevated for 30 days 2, 3
• Up to 24-25% of patients have concurrent silent brain infarction on diffusion-weighted MRI at the time of presentation 1, 3

Shared Risk Factors with Stroke

Cigarette smoking, hypertension, diabetes, hyperlipidemia, cardiac disease including atrial fibrillation, and coagulopathy are all important modifiable risk factors. 1, 3

Immediate Management

Once the diagnosis of retinal artery occlusion is confirmed, the patient should be immediately referred to the closest emergency department affiliated with a stroke center with a note indicating "Ocular TIA" or "Ocular Stroke." 1, 3

Do NOT delay transfer for additional ophthalmologic testing. 1, 3

Critical Evaluation at Stroke Center

• Brain MRI with diffusion-weighted imaging to identify concurrent stroke 1, 3
• Vascular imaging (CTA or MRA) to assess carotid stenosis 1, 3
• Cardiac evaluation including ECG and echocardiography 1, 2
• ESR and CRP in patients over 50 years to rule out giant cell arteritis 2, 3

Giant Cell Arteritis Exception

If GCA is suspected based on age >50 and associated symptoms, immediate empiric high-dose corticosteroids must be started without waiting for biopsy confirmation. 1, 2, 3 This is critical to prevent vision loss in the fellow eye.

Common Pitfalls to Avoid

• Never assume that vision improvement eliminates stroke risk - stroke risk remains highest in the first 7 days even if vision recovers 3
• Never delay GCA treatment for temporal artery biopsy - empiric steroids should be started immediately in suspected cases 3
• Never underestimate cardiovascular risk - new significant cardiovascular conditions are discovered in up to 70% of CRAO patients 1, 3
• Never perform extensive ophthalmologic workup before stroke center referral if vascular etiology is suspected 1, 3
• Always check inflammatory markers in patients over 50, regardless of whether classic GCA symptoms are present 3

Prognosis

The natural prognosis for visual recovery is poor, with less than 10% of nonarteritic CRAO patients experiencing any meaningful recovery of vision. 1 This contrasts sharply with GCA-related cases treated promptly with corticosteroids, which can have better outcomes. 1