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  • Updated 06.18.2022
  • Released 02.08.2001
  • Expires For CME 06.18.2025

Transient visual loss

Introduction

Overview

Transient visual loss, meaning vision loss that resolves spontaneously within 24 hours, can have causes ranging from benign to emergent and potentially catastrophic, making proper evaluation urgent. Any disorder that can cause temporary dysfunction of the afferent visual system, including the eye, retina, optic nerve or tracts, lateral geniculate body, geniculocalcarine tract, or calcarine visual striate and peristriate cortices, can cause transient visual loss. As the vision loss is transient, the examination is often unrevealing, making the history particularly essential for diagnosis.

Differentiating monocular and binocular symptoms is the first step toward identifying the etiology. Binocular transient visual loss may be due to posterior circulation ischemia, migraine visual aura, or seizure. Monocular transient visual loss may be due to thromboembolism or vasospasm of the central retinal artery, ocular causes such as acute angle closure glaucoma and pigmentary dispersion syndrome, or other causes, including migraine visual aura.

For the purposes of this review, transient vision loss refers to relatively brief (hours or shorter) episodes of transient visual loss or transient visual disturbances that resolve spontaneously. Causes of vision loss that are reversible by treating the underlying cause, such as posterior reversible encephalopathy syndrome and hyperglycemic nonketotic homonymous hemianopia, are outside the scope of this review. Conditions that affect the efferent visual system, meaning the oculomotor system, may also cause transient or intermittent visual symptoms, including difficulty focusing, double vision, and oscillopsia, but this article focuses on disorders that cause a transient change to the afferent visual system.

Key points

• Transient binocular visual loss may be due to posterior circulation ischemia, migraine, or seizure.

• Transient monocular visual loss may be due to thromboembolism or vasospasm of the central retinal artery; giant cell arteritis; papilledema; ocular causes, such as acute angle closure glaucoma; or other causes, including migraine.

• The most important job of the clinician is to identify and protect the patient from dangerous causes of transient vision loss (ischemic, arteritic, angle closure glaucoma, papilledema).

Historical note and terminology

The clinical importance of transient monocular visual loss was initially described in detail by C Miller Fisher (20; 21; 16), who emphasized that transient visual loss in a single eye may occur due to thromboembolism from severe occlusive disease of the ipsilateral internal carotid artery in the neck. Associated episodes of contralateral hemibody weakness are also suggestive of thromboembolic events due to carotid stenosis. Fisher also described and illustrated the funduscopic findings in a patient that he observed during an attack of transient monocular blindness (18). Pessin and colleagues subsequently showed that a high percentage of patients who had episodic transient monocular visual loss and transient hemispheric dysfunction referable to the ipsilateral cerebral hemisphere had severe stenosis or occlusion of the ipsilateral internal carotid artery (47).

The term “amaurosis fugax,” Greek for “swift, transient, or fleeting darkness,” is sometimes used as a synonym for transient monocular vision loss, specifically transient monocular vision loss due to a thromboembolic cause. Some providers may use it as a description of undifferentiated symptoms, and others may assume that it means that a thromboembolic cause has already been confirmed. Given these different usages, this term is imprecise and can mistakenly imply to other providers that an ischemic etiology has been confirmed; thus, it is best avoided (19; 07; 41).

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