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Amaurosis Fugax: Essentials for the Optometric Physician
Brett G. Bence, OD FAAO
Northwest Eye Surgeons, PC
Seattle, Washington
A. Statistical evidence – AF, TIA, and stroke
a. Strokes per year in US: 700,000
b. 30% are recurrent stroke
c. 25% mortality
d. TIA and AF: greatest risk of stroke is 1st week
e. TIA and AF: 10.5% risk of stroke in 90 days
B. AF vision loss
a. Transient
b. Partial to total loss
c. Often begins in the upper field
d. Painless
e. Unilateral (except vertebral-basilar)
f. Commonly no precipitating factor
g. Fully reversible
C. Vascular anatomy review
a. Internal carotid artery (ICA)
b. External carotid artery (ECA)
c. Circle of Willis
D. Thromboembolism ICA
a. Full occlusion / high grade stenosis / ulcerated lesion
b. Proximal at bulb
c. Mid ICA at siphon
d. Other locations
i. Aortic arch
ii. Common carotid
E. Thromboembolism carotid sinus
a. Biopathology of hemodynamic shear stress
b. Greatest plaquing: carotid sinus outer wall
c. Flow stasis = shear stress
d.  shear stress = atheroprotective endothelial response
F. Thromboembolism vertebral – basilar arteries
a. Brain stem ischemia
b. Homonymous vision symptoms
c. Vertigo, dysphagia, diplopia, dysarthria, others
d. Medical management
e. Endovascular surgery
i. Investigational
G. Thromboembolism cardiac
a. ≈ 20% ischemic strokes
b. Often calcific
c. Valve disease
i. Rheumatic mitral valve disease
ii. Mitral valve prolapse
d. Prostetic valves
e. Endocarditis
f. Patent foramen ovale
H. Nearly half (43%) of young patients < 50 yrs with cryptogenic stroke in this study have a patent
foramen ovale
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Other conditions with clot risk
a. Pregnancy, birth control pills
b. Hypercoagulable conditions
i. Mostly pediatric, young adults
ii. Inherited thrombophilias
1. Protein C; Protein S
2. Factor V
3. Leiden
4. Antithrombin III deficiency
Hemodynamic cause
a. Relative retinal vascular insufficiency
b. Generalized atherosclerosis
c. Weak CRA pressure
d. Induced by
i. Exercise
ii. Bright light (brightness intolerance)
iii. Postural changes / hypotensive episodes
Hemodynamic – other considerations
a. Low cardiac output, CHF
b. ECA and ICA high grade stenosis
c. Takayasu’s disease (inflammatory arteritis)
d. Hyperviscosity conditions
e. ICA dissection
f. Carotid aneurysm
Idiopathic cause
a. No identifiable lesion or cause
b. Vasospastic (?)
Ocular presentations with transient blur
a. Transient obscurations with papilledema
b. Occult AION
c. Malignant hypertension
d. Prodrome of CRVO
e. Optic neuritis
f. Compression of ON, optic chiasm
g. Gaze-induced AF 2° orbital tumor
Further considerations for patient reported “sudden loss of vision” or transient blur
a. Vitreous hemorrhage
b. Hyphema
c. Glaucoma, extreme elevated intraocular pressure
d. Vitreous floaters
e. “overnight” cataract, PCO
f. corneal decompensation
g. Many others
Patient presentation with AF: in-office examination
a. Detailed chief complaint, history
b. BP, pulse, cervical and heart auscultation
c. Neurologic eye assessment
d. Biomicroscopy
e. Ophthalomoscopy
i. Check for retinal emboli, retinal edema, BRAO, disc edema
f. Ophthalmodynamometry, relative CRA diastolic and systolic pressure
g. Exophthalmometry, orbital disease
Ocular ischemic syndrome
a. Hypoperfusion retinopathy
b. Posterior or anterior segment rubeosis
Supplemental tests: Laboratory
R.
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a. Sed rate and CRP
b. CBC
c. Platelets
d. Lipid panel
e. Glycosylated Hb and FBS
f. Homocysteine (if elevated: 2X relative risk factor for stroke)
g. Antinuclear antibody (Lupus)
h. Antiphospholipid antibody
Supplemental tests: cerebrovascular studies
a. Noninvasive Doppler ultrasound
i. B-mode
ii. Continuous wave
iii. Duplex
1. Combines B-mode and pulsed Doppler
iv. Transcranial Doppler
b. Magnetic resonance angiography
c. Arteriography
d. Factors associated with higher risk of stroke
i. ICA stenosis of 80-94%
ii. History of hemispheric TIA or stroke
iii. History of intermittent claudication
iv. Absence of collateral circulation
v. Age > 75
vi. Male > female
Supplemental tests: cardiac studies
a. Echocardiography
Treatment 2007: Optometry’s role
a. Identify and manage if ocular cause
b. Measure BP, pulse, auscultation
c. Stat ESR and CRP
d. Individualize suspicion and focus of examination
i. Age
ii. Health and family history
e. Communicate with family practitioner
f. Management may include, but is not limited to
i. Systemic work-up, blood studies
ii. Duplex, Doppler ultrasound = cerebrovascular studies
iii. Echocardiogram = cardiac studies
iv. ASA, antiplatelet option (individualize risk)
Management concerns
a. Misdiagnosis of symptoms and incorrect working diagnosis
b. Underestimate urgency of situation
c. No follow-up with primary care physician or patient
d. Referral to an inappropriate subspecialist
Surgical treatment if symptomatic high grade stenosis
a. Carotid endarterectomy
b. NASCET study summary
Options for symptomatic moderate grade stenosis
Angioplasty and stenting
a. Long term results pending
b. Primary advantage is local anesthetic
c. Catheter with balloon
d. Metal-mesh stent
Medical management
a. Meta-analysis of 21 randomized trials