Gaze-Evoked Amaurosis

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Article initiated by:

Shu Feng, MD

All contributors:

Victoria Cegielski, Grant.Howell, Eugene May, Nagham Al-Zubidi, MD, Shu Feng, MD, Mary Labowsky, MD

Assigned editor:

Mary Labowsky, MD

Review:

Assigned status Up to Date

 by Mary Labowsky, MD on November 6, 2024.

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Contributing Editors:	add

Disease Entity

Gaze-evoked amaurosis (GEA) is a unique cause of transient vision loss whereby patients experience vision loss only in a particular direction of eccentric gaze; classically, it is associated with intraconal tumors causing position-dependent compression of the optic nerve.

Etiology

When a history of gaze-evoked amaurosis is elicited, or if it can be demonstrated on exam, a search for orbital pathology should be conducted. In over 80% of reported cases, intraconal pathology is the cause. Examples of reported compressive pathologies that cause GEA include foreign bodies, facial fractures, and tumors such as optic sheath meningiomas, cavernous hemangiomas, or optic nerve gliomas, thyroid orbitopathy, as well as inflammatory conditions like sarcoidosis, idiopathic orbital inflamation, and myositis. Extraconal pathologies, though less common, may also cause gaze-evoked amaurosis if large enough to put pressure on the optic nerve. A case of idiopathic intracranial hypertension causing GEA was reported, in which it was proposed that in an eccentric position of gaze, compression of a tense dilated optic nerve sheath can result in further elevation of intra-sheath pressure, compromising blood flow to the retina. There has also been a cause of an intracavernous meningioma with compression of the carotid artery, leading to reduced perfusion of the right ophthalmic artery, particularly in abduction which causes stretch of adjacent tissues.

Pathophysiology

The exact mechanism behind gaze-evoked amaurosis has not been clearly defined. It seems most likely that position-dependent compression of the optic nerve results in inhibition of axonal impulse propagation through the nerve, causing transient vision loss. Another theory is that compression causes reduced blood flow and retina/optic nerve ischemia, which results in temporary vision loss.

Diagnosis

History

Some patients may not initially notice their visual symptoms because the amaurosis is only induced in specific gaze positions. However, with a directed history patients may report vision loss when turning their heads and maintaining eccentric gaze, such as when driving or shaving one’s armpits. The vision loss returns to baseline when gaze is returned to primary position.

Physical examination

Examination should start with assessing vision, pupils, pressure, and color in primary gaze for an established baseline. From there, evaluating sustained eccentric gaze in the different cardinal positions should be performed for at least 10-15 seconds. If gaze-evoked amaurosis is elicited, patients will likely subjectively complain of central vision loss, visual field defect, or color desaturation. An afferent pupillary defect may be present in eccentric gaze only. Though one should try to spare prolonged optic nerve compression, if intraocular pressures are taken in the gaze of amaurosis, they may reveal elevated readings. On return to primary gaze, the findings should resolve to baseline within a few seconds.

Most commonly, having a patient look the opposite direction to where the pathology is located elicits amaurosis; for example, a patient would experience vision loss when abducting their eye if the lesion was medial to the nerve. However, this is not always a consistent finding and should not be used to localize the disease.

Depending on the degree of baseline optic neuropathy, central vision, color vision, and visual fields may be variably affected. Dilated fundus exam often reveals a swollen optic disc from intraconal optic nerve compression.

Diagnostics

• Neuroimaging of the orbit (MRI orbits with and without contrast or CT orbits with contrast)

Management

Treatment of amaurosis is aimed at its underlying etiology. Following treatment of the underlying cause, most patients experience resolution of the gaze-evoked amaurosis and its other manifestations (APD, decreased visual acuity, color desaturation, etc.)

Prognosis

The presence of gaze-evoked amaurosis is not predictive of permanent vision loss. Most patients who receive treatment for the underlying cause of their amaurosis will experience a return to visual baseline and resolution of abnormal exam findings.