CHAPTER 5

The Patient With Transient Visual Loss

Transient visual loss is the sudden loss of visual function (partial or complete) in 1 or both eyes that lasts less than 24 hours. In general, the most common cause of transient monocular visual loss (TMVL) is retinal ischemia due to carotid artery disease. In comparison, the most common cause of transient binocular visual disturbance is migraine. A systematic approach to the evaluation of patients with transient visual loss is imperative, beginning with a detailed historical account of the visual loss that includes the following points:

Monocular versus binocular visual loss. Establishing transient visual loss as monocular or binocular is important for localizing the lesion; monocular loss implies a prechiasmal problem, whereas binocular loss is a chiasmal or retrochiasmal problem. Clinicians should be aware that transient homonymous hemianopia is frequently misperceived and reported by the patient as a monocular visual loss in the eye with the temporal field deficit.

Age. In a patient younger than 50 years, migraine or vasospasm is the most likely cause of transient visual loss. An important exception in pregnant women is eclampsia, in which transient visual loss may be a harbinger of more serious and permanent visual loss, usually occurring within days of delivery (see Chapter 14). In older patients, cerebrovascular disease and giant cell arteritis should be considered.

Duration of visual loss. Monocular or binocular transient obscurations of vision lasting only seconds are often precipitated by a change in posture and are a common complaint in patients with optic disc drusen or papilledema. TMVL lasting several minutes (typically no more than 15 minutes) is characteristic of symptomatic ipsilateral internal carotid artery stenosis. The scintillating scotoma typical of migraine is binocular and lasts 20–30 minutes. The duration of visual loss from retinal artery vasospasm is variable and may last from seconds to an hour.

Pattern of visual loss and recovery. A descending curtain in 1 eye is the classic description of TMVL from retinal emboli, although tunnel-like contraction of vision or sudden loss of vision has also been reported. An altitudinal aspect of visual loss strongly suggests carotid artery disease, but vasospasm can sometimes cause similar visual symptoms. Visual loss or disturbance precipitated by exercise also evokes consideration of vasospasm, as well as of demyelinating disease. Uhthoff phenomenon (transient visual blurring with physical activity or elevation in body temperature) frequently occurs in patients with a current or previous episode of optic neuritis (see Chapter 4). Posterior circulation ischemia typically causes complete