Transient visual loss has a number of potentially critical causes which are listed below. But one of the most important is transient ischemic attack. A person who has suffered a TIA is at much increased risk of suffering a stroke in the hours, days, and weeks immediately following the TIA.
Therefore, immediate evaluation of the TIA (which is a clinical diagnosis) must be performed. The purpose is to see if there is a treatment (such as carotid endarterectomy or medical therapy) that can be begun to lessen the risk of a stroke.
The symptoms of amarosis fugax are:
Monocular visual loss that usually lasts seconds to minutes, but may last up to 1 to 2 hours. Vision returns to normal. (Reference 1 p 269).
But bilateral transient blurred vision can also be due to a transient inschemic attack from vertebrobasilar artery insufficiency and work up is at least as urgent as for monocular transient visual loss.
Ataxia, vertigo, dysarthria or dysphasia, perioral numbness, and hemiparesis or hemisensory loss may accompany the visual symptoms [of vertebrobasilar artery insufficiency]. History of drop attacks (the patient suddenly falls to the ground without warning or loss of consciousness). Recurrent attacks are common. (Reference 1 p 271)
All of what follows is from Reference 1, pp 269 + 270:
Differential Diagnosis of Transient Visual Loss
- Papilledema. . .
- Giant Cell Arteritis. . .
- Impending central retinal vein occlusion. . .
- Migraine with auroa. . .
- Acephalgic migraine. . .
- Vertebrobasilar artery insufficiency. . .
- Basilar artery migraine. . .
- Vertebral artery dissection. . .
- Intermitent intraocular hemorrhage. . .
- Others: Optic nerve head drusen, intermitent angle closure, intermittent pigment dispersion.
- Embolus from the carotid artery (most common), heart or aorta.
- Vascular insufficiency as a result of arteriosclerotic disease of vessels anywhere along the path from the aorta to the globe causing hypoperfusion often precipitated by a postural change or cardiac arrythmia.
- Hypercoagulable/hyperviscosity state (See Reference 2).
- Rarely, an intraorbital mass may compress the optic nerve or a nourishing vessel in certain gaze position, causing gaze evoked transient visual loss.
- Amaurosis fugax is considered by the American Heart Association to be a form of TIA. Current guidelines (see Reference 3) recommend MRI with diffusion weighted imaging, urgent carotid and cardiac studies and neurology consultation [and ophthalmology consultation].
- Immediate ESR, CRP, and platelet count when Giant Cell Arteritis (CGA) is suspected.
- through 6. . . . .
7. CBC with differential, fasting blood sugar, hemoglobin A1c, and lipid profile (to rule out polycythemia, thrombocytosis, diabetes, and hyperlipidemia).
- The Wills Eye Manual: Office and Emergency Room Diagnosis and Treatment of Eye Disease, 7th ed 2017.
- Hyperviscosity Syndrome, updated Nov 23 2015 from Emedicine/Medscape, which also can be a cause of transient visual loss.
- Guidelines for the prevention of stroke in patients with stroke and transient ischemic attack: a guideline for healthcare professionals from the American Heart Association/American Stroke Association [PubMed Abstract] [Full Text HTML] [Full Text PDF] [Executive Summary Full Text PDF] [Correction] Stroke. 2014 Jul;45(7):2160-236. doi: 10.1161/STR.0000000000000024. Epub 2014 May 1.