What Causes Double Vision? How Is It Treated?

Suddenly seeing two images of everything can be frightening and make everyday activities difficult. Known medically as diplopia, double vision means perceiving a single object as two separate images. The cause may lie in the eye itself or in the muscles, nerves, or nervous system involved in controlling eye movements.

What Causes Double Vision?

During an examination, an important first step is determining whether double vision occurs in one eye alone or only when both eyes are open. A change when one eye is covered provides a useful clue, but does not establish a diagnosis on its own.

Double Vision That Persists in One Eye

Double vision that continues in the uncovered eye when the other eye is closed may be related to the eye’s optical structures. Possible causes include an irregular eye surface, dry eye, cataract, or astigmatism. Treatment depends on the cause identified during the examination.

Double Vision When Both Eyes Are Open

When the eyes cannot align on the same point, the brain may be unable to combine the two images. Cranial nerve palsies affecting eye movements, strabismus, thyroid eye disease, and some neurological conditions can cause this problem. A neurological assessment or imaging may be recommended when needed.

What Should You Do If Double Vision Starts Suddenly?

New double vision, especially when it starts suddenly, needs prompt assessment. Seek emergency care if it is accompanied by a severe headache, a drooping eyelid, unequal pupils, difficulty speaking, weakness, or loss of balance. Do not drive while experiencing double vision.

How Is Double Vision Treated?

Treatment is tailored to the cause and the characteristics of the eye misalignment. Surgery is not necessary in every case, and no single treatment is suitable for everyone. Identifying and, when necessary, treating the underlying condition is a priority.

Prism Glasses

Prisms change the direction of light to help combine the images from the two eyes. They may reduce double vision in suitable types and degrees of misalignment. Temporary prisms applied to spectacle lenses or permanent prism lenses may be used. The appropriate prism is determined through an eye examination and measurements of the misalignment.

Botulinum Toxin Injections

In selected patients, a botulinum toxin injection into an eye muscle can temporarily reduce its action and help improve alignment. It may be considered during recovery from certain nerve palsies or for particular types of strabismus. Its effect is temporary, and repeat treatment may be needed. Possible risks, including temporary eyelid drooping or a change in the deviation, should be discussed with the treating doctor.

Other Treatment Options

Depending on the cause, treatment may involve managing the eye surface, prescribing appropriate glasses, treating a cataract, or performing strabismus surgery. The aim is both to address the double vision and to manage the condition responsible for it.

When Should You See an Eye Doctor?

Do not wait for new or recurring double vision to resolve on its own. Early assessment helps identify important causes and allows an appropriate treatment plan to be made.

This article provides general information. Diagnosis and treatment require an eye examination and an individual care plan.