What is the emergency evaluation and initial management for an adult who presents with sudden blindness?

Emergency Evaluation and Management of Sudden Blindness

Immediately refer the patient to a certified stroke center emergency department or rapid-access TIA clinic, as sudden vision loss represents an ocular stroke equivalent requiring urgent neurological evaluation within 24 hours. 1, 2

Immediate Triage and Referral

• Treat sudden vision loss as a neurological emergency, not just an ophthalmologic problem—the American Heart Association considers central retinal artery occlusion a stroke equivalent, and up to 25% of these patients have concurrent silent brain infarction on MRI. 2

• Do not perform extensive ophthalmologic workup before stroke center referral if vascular etiology is suspected; instead, send the patient immediately with a note stating "Ocular TIA" or "Ocular Stroke." 2

• The stroke risk is highest within the first 7 days after retinal vascular events (up to 15% at 7 days, 25% at 30 days), making time-sensitive evaluation critical. 2, 3

Critical Initial Assessment in Emergency Department

History Elements to Rapidly Establish:

• Onset characteristics: Sudden (seconds to minutes) versus gradual, monocular versus binocular, complete versus partial vision loss 1, 4

• Pain presence: Painful vision loss suggests acute angle-closure glaucoma, optic neuritis, or giant cell arteritis; painless suggests vascular occlusion or retinal detachment 4, 5

• Age over 50 years: Mandates immediate evaluation for giant cell arteritis with associated symptoms including jaw claudication, scalp tenderness, temporal tenderness, headaches, and constitutional symptoms 2, 4

• Trauma history: If present, requires non-contrast thin-section orbital CT with multiplanar reconstructions to identify fractures, foreign bodies, and optic canal narrowing 1

• Vascular risk factors: Hypertension, diabetes, hyperlipidemia, smoking, cardiovascular disease 2, 4

Physical Examination Priorities:

• Visual acuity measurement in each eye separately 5

• Pupil assessment for relative afferent pupillary defect (Marcus Gunn pupil), which indicates optic nerve or severe retinal pathology 4, 5

• Confrontational visual field testing to determine if defect is monocular versus binocular, complete versus sectoral 5

• Fundoscopy to identify retinal artery occlusion (pale retina with cherry-red spot), retinal detachment (curtain-like defect), or papilledema 4, 5

• Extraocular movements and assessment for proptosis or enophthalmos 1

Urgent Diagnostic Workup (Within 24 Hours)

Neuroimaging:

• Brain MRI with diffusion-weighted imaging is the preferred modality, as it identifies concurrent stroke present in up to 24% of retinal vascular events. 1, 2

• If MRI unavailable, perform head CT without contrast. 1

Vascular Imaging:

• Noninvasive cervicocephalic vessel imaging (MRA, CTA, or carotid ultrasound/transcranial Doppler) should be obtained routinely, as clinically significant carotid stenosis is found in up to 70% of symptomatic retinal vascular events. 1, 2

Laboratory Studies:

• Routine blood tests: Complete blood count with platelets, chemistry panel, hemoglobin A1C, prothrombin time/partial thromboplastin time, fasting lipid panel 1

• ESR and CRP are mandatory in patients over 50 years to screen for giant cell arteritis—ESR >60 mm/h has high likelihood ratio for diagnosis. 1, 2, 4

Cardiac Evaluation:

• Electrocardiography immediately upon presentation 1

• Prolonged cardiac monitoring (inpatient telemetry or Holter) if etiology unclear after initial imaging 1

• Echocardiography (at least transthoracic) is reasonable, especially when no cause identified by other workup elements; transesophageal may be needed for left atrial thrombus, patent foramen ovale, or valvular disease. 1

Immediate Treatment Based on Suspected Etiology

Giant Cell Arteritis (Suspected):

• Start empiric high-dose corticosteroids immediately (1-2 mg/kg/day prednisone or equivalent) without waiting for temporal artery biopsy to prevent vision loss in the contralateral eye. 2, 3, 4

• Never delay steroid initiation for biopsy confirmation—this is a critical pitfall that can result in bilateral blindness. 2

Acute Angle-Closure Glaucoma:

• Pilocarpine eye drops, oral or intravenous acetazolamide, and intravenous mannitol for immediate intraocular pressure reduction. 4

Retinal Artery Occlusion:

• Consider hyperbaric oxygen therapy (100% oxygen over 9 hours) if available within appropriate time window, which has demonstrated efficacy in small randomized trials. 3

• Secondary stroke prevention with antiplatelet therapy as recommended by neurology consultation. 6

Optic Neuritis:

• High-dose intravenous corticosteroids if confirmed, with subsequent evaluation for multiple sclerosis. 4

Common Pitfalls to Avoid

• Never assume vision improvement eliminates stroke risk—stroke risk remains highest in first 7 days even if vision spontaneously improves or reperfuses. 2

• Never underestimate cardiovascular risk—new significant cardiovascular conditions are discovered in up to 70% of central retinal artery occlusion patients during workup. 2, 3

• Never skip inflammatory markers in patients over 50, regardless of whether classic giant cell arteritis symptoms are present—atypical presentations are common. 2

• Never perform MRI if metallic foreign body suspected in trauma cases—use CT instead. 1

Disposition and Follow-Up

• Admission or observation in stroke center for patients with confirmed vascular etiology or high-risk features 1

• Ophthalmology consultation within 24 hours for all cases, with ongoing monitoring for neovascular complications (iris/retinal neovascularization, neovascular glaucoma) 6

• Neurology follow-up for stroke prevention strategies and management of identified vascular risk factors 6

• Coordinate care between neurology, ophthalmology, and primary care for comprehensive secondary prevention 6