Monocular vision loss may be transient or persistent. When patients present with transient visual symptoms that they attribute to one eye, for you to be more certain that your patient’s symptom was truly monocular and not a hemianopic disturbance, the patient would have had to have covered the bad eye during the event to confirm that the vision was intact in the good eye. Some patients do initiate this test on their own during an episode of vision loss, but you may need to specifically inquire if the patient did this.

Patients with monocular visual problems do not usually present with significant functional deficits from their vision loss, as long as the remaining eye has intact visual fields. In other words, unlike patients with hemianopsias, patients with purely monocular vision loss are less likely to bump into objects because of their visual dysfunction.

Amaurosis fugax (meaning fleeting blindness) is an important kind of transient monocular vision loss that may be seen in patients with retinal ischemia, such as can be associated with carotid stenosis or temporal arteritis. Patients describe a brief (seconds or minutes) loss of vision in
one eye as “like a shade coming down.” As the symptoms resolve, the patient may describe the shade coming back up.

Patients with optic neuritis usually present with monocular vision loss that progresses over a period of days and lasts for weeks, and it is often associated with pain on eye movement.

Patients with visual field loss often do not recognize the concept of a visual field or a visual field deficit. They may misinterpret their homonymous visual field deficits as monocular (i.e., a patient may interpret a left homonymous hemianopsia as a visual problem involving the left eye alone).

Patients with hemianopic visual field cuts sometimes present with symptoms of the consequences of their deficits, rather than with a primary visual complaint. They may tell you they consistently bump into objects on one side, or they may have been involved in a motor vehicle collision because of their visual deficit.

Patients with hemianopsias may present with a vague visual complaint that they have difficulty describing. Those with left homonymous hemianopsias may complain of difficulty reading, not recognizing that their difficulty is due to consistently missing the first (left) parts of sentences. Patients with bitemporal field loss may complain of difficulty with their peripheral vision.

A common form of transient hemianopic field deficit is the visual disturbance of a migraine aura. Migrainous visual disturbances typically present as a scintillating (shining) zigzag or herringbone-like pattern, sometimes in the form of a C, occurring in the left or right visual field and gradually growing over approximately a 15-minute period before resolving. This migrainous visual disturbance may or may not be followed by a headache.