Double Vision (Diplopia)

What is Double Vision (Diplopia)?

Double vision (diplopia) means seeing two images of a single object. It can be binocular (present only when both eyes are open, disappearing when either eye is closed) or monocular (persisting even when the other eye is closed). Binocular double vision indicates a misalignment of the eyes and may point to neurological, muscular, or orbital causes. Monocular double vision is usually caused by an optical problem within the eye itself, such as cataracts, corneal irregularity, or refractive error. Determining which type you have is the first step in finding the cause and the right treatment.

Symptoms

• Seeing two images of a single object — side by side, one above the other, or at an angle
• Double vision that worsens in a particular direction of gaze
• Headaches or eye strain
• Difficulty reading, driving, or navigating stairs
• Nausea or dizziness from visual confusion
• Head tilting or turning to reduce the double image

Diagnosis

The first step is determining whether the double vision is monocular or binocular using the cover test. For binocular diplopia, a detailed motility examination identifies which eye muscles or nerves are affected. Prism measurements quantify the misalignment. Depending on the suspected cause, imaging (MRI of the brain and orbits, CT angiography), blood work (thyroid function, inflammatory markers, acetylcholine receptor antibodies), or other tests may be ordered.

Treatment

Treatment targets the underlying cause. If a systemic condition such as myasthenia gravis or thyroid eye disease is identified, treating that condition often improves the double vision. Prism glasses can immediately reduce or eliminate double vision by optically realigning the images. For stable misalignments that don't resolve with treatment of the underlying cause, strabismus surgery can permanently restore single vision. In urgent situations, temporary measures like patching one eye provide immediate relief.