What are the causes of fleeting blindness, particularly in patients with a history of hypertension, diabetes, or cardiovascular disease?

Causes of Fleeting Blindness

Fleeting blindness (transient vision loss) is most commonly caused by retinal ischemia from atherothromboembolism originating at the ipsilateral internal carotid artery, particularly in patients with hypertension, diabetes, or cardiovascular disease, and must be treated as a medical emergency requiring immediate stroke evaluation. 1, 2

Primary Vascular Causes (Most Common in At-Risk Patients)

Amaurosis Fugax (Transient Monocular Vision Loss)

• Atherothromboembolism from carotid artery stenosis is the leading cause, with clinically significant carotid stenosis discovered in up to 70% of symptomatic patients 1, 2
• Cardiogenic embolism from atrial fibrillation, though less common than carotid disease 2
• Carotid artery dissection, particularly following neck trauma or pain 3
• Hypotension causing inadequate optic nerve perfusion 3
• Stroke risk is highest within the first 7 days and remains elevated for 30 days, with up to 25% of patients experiencing subsequent stroke 3, 1

Retinal Artery Occlusion

• Central or branch retinal artery occlusion presents with painless, sudden vision loss in patients with vascular risk factors 3, 4
• Associated with hypertension, diabetes, hyperlipidemia, and coronary artery disease 3
• Silent brain infarction is present in up to 24% of patients with acute ocular vascular events 1

Retinal Vein Occlusion

• Branch retinal vein occlusion occurs six to seven times more commonly than central retinal vein occlusion 3
• Risk factors include hypertension, hyperlipidemia, diabetes, and coronary artery disease 3
• Patients have increased risk of cardiovascular events and all-cause mortality 3

Arteritic Causes (Critical to Identify)

Giant Cell Arteritis

• Must be considered in all patients over 50 years presenting with transient vision loss 1, 4
• Associated symptoms include temporal tenderness, jaw claudication, scalp tenderness, proximal muscle pain, weight loss, fever, and malaise 1, 4
• ESR and CRP are typically elevated 1, 4
• Requires immediate high-dose corticosteroids (40-60 mg/day prednisone equivalent) before biopsy confirmation to prevent permanent blindness in the fellow eye 1, 4

Transient Visual Obscurations (Distinct Entity)

Papilledema-Related

• Brief episodes lasting only seconds (not minutes), representing transient optic nerve head ischemia 5
• Associated with raised intracranial pressure, particularly idiopathic intracranial hypertension 5
• Accompanied by progressive headache and pulsatile tinnitus 5
• Fundamentally different from amaurosis fugax, which lasts minutes and requires stroke workup 5

Ocular Causes

Acute Angle-Closure Glaucoma

• Presents with ocular pain, headache, nausea, and elevated intraocular pressure 4
• Requires immediate treatment with pilocarpine, acetazolamide, and mannitol 4

Other Ocular Conditions

• Vitreous or anterior segment hemorrhage 3
• Retinal or choroidal detachment (presents with curtain-like visual field defect) 3, 4
• Primary vasospasm or blepharospasm 3

Neurological Causes

Optic Neuritis

• Demyelinating condition featuring color desaturation, relative afferent pupillary defect, and pain with eye movements 4
• Often initial manifestation of multiple sclerosis 3
• Requires high-dose steroids and evaluation for multiple sclerosis 4

Post-Traumatic Cortical Blindness

• Transient bilateral vision loss following minor head trauma with normal pupillary response and funduscopic examination 6
• Vision returns within minutes to hours with no neurological sequelae 6

Metabolic and Systemic Causes

Hypercoagulable States

• Factor V Leiden, homocysteinemia, antiphospholipid antibodies 3
• Systemic lupus erythematosus increases CRVO incidence 3.5-fold 3
• 58% of patients with CRVO onset before age 50 have nontraditional risk factors requiring systemic evaluation 3

Metabolic Derangements

• Glucose imbalance (hypoglycemia or hyperglycemia) 3
• Susac syndrome (triad of hearing loss, CNS lesions, and BRAOs in younger patients) 3

Critical Management Algorithm

Immediate Actions:

1. Refer to emergency department or stroke center within 24 hours of symptom onset 1
2. Obtain diffusion-weighted MRI of brain 1
3. Perform carotid artery imaging (duplex ultrasound initially) 1
4. Check ESR and CRP if patient is over 50 years 1
5. Initiate antiplatelet therapy (aspirin 75-325 mg daily) 1

Common Pitfalls to Avoid:

• Delaying referral beyond 24 hours is the most critical error 1
• Failing to evaluate for giant cell arteritis in patients over 50 years 1
• Overlooking silent brain infarctions on imaging despite transient symptoms 1
• Confusing transient visual obscurations (seconds duration, papilledema-related) with amaurosis fugax (minutes duration, vascular) 5