Diplopia (Double Vision)

Diplopia is the medical term for double vision, where a single object appears as two images, and can be caused by a wide range of eye and neurological conditions.

Common symptoms

Seeing two images of the same object, either side by side, one above the other, or at an angle, sometimes only in certain directions of gaze or when one eye is covered.

Description

Double vision is a symptom rather than a condition in its own right, but it is a common reason for people to seek urgent help because it can be disorientating and unsafe. The first step is usually to work out whether it goes away when one eye is covered.

If double vision disappears with one eye covered, it is called binocular diplopia and usually comes from misalignment of the eyes. Causes include nerve palsies, thyroid eye disease, myasthenia gravis, stroke, and decompensated squint. If it remains with one eye covered, it is monocular diplopia and often relates to problems such as cataract, corneal irregularity, or high astigmatism.

Treatment depends entirely on the underlying cause. It may include glasses with prisms, treating the root condition, surgery on the eye muscles, or simple short-term measures such as patching one eye. Any new or sudden-onset double vision should be assessed promptly.