Ocular Causes

Nonvascular ocular causes of TVL are very common and are usually excluded by an ocular examination.

Table 5-1 Causes of Transient Monocular Visual Loss

Tear-film abnormalities often result in blurred vision that improves with blinking or a tear supplement. These abnormalities may also be associated with brief sharp or stabbing pain. Slit-lamp examination may reveal keratitis sicca. Dry eye can also provoke blepharospasm, which can lead to moments of visual loss (see Chapter 11, Fig 11-10).

Opacities, inflammation, or blood in the media of the anterior chamber or the vitreous can also cause episodic visual disturbance. For example, recurrent hyphema occasionally causes TMVL in patients with intraocular lenses who have uveitis-glaucoma-hyphema (UGH) syndrome. Release of pigment in the anterior chamber during exercise may occur in pigment dispersion syndrome.

Transient monocular visual obscurations that are accompanied by halos and pain should always prompt gonioscopy of the anterior chamber angle to assess for angle-closure glaucoma. The anterior lens should be inspected for glaukomflecken, which indicate prior episodes of angle-closure glaucoma.

TVL, prolonged visual recovery, or persistent afterimages following exposure to bright light suggests macular disorders, such as serous detachment, age-related macular degeneration, or ocular ischemia. In such patients, the photostress recovery test is often abnormal.

Patients with papilledema or congenital ONH anomalies (eg, drusen or anomalous optic nerve) experience grayouts or blackouts of vision (so-called transient visual obscurations). Such episodes are typically brief (less than 10 seconds) and often precipitated by changes in posture.

Kaiboriboon K, Piriyawat P, Selhorst JB. Light-induced amaurosis fugax. Am J Ophthalmol. 2001;131(5):674–676.

Excerpted from BCSC 2020-2021 series: Section 5 - Neuro-Ophthalmology. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.