What Is Diplopia? - Definition, Causes & Treatment

Instructor: Marisela Duque

Marisela teaches nursing courses at the college level. She also works as a unit educator, teaching experienced nurses about changes in nursing practice.

After completing this lesson, you will be able to define diplopia and explain its causes and treatment options. A short quiz follows this lesson so that you can test your new knowledge.

Seeing Double

Sallie is looking forward to her first day of high school. But when she gets to her first freshman class, she has a sense that something is very wrong! Sallie tries to concentrate on her teacher's lecture, but she is seeing two of him! In fact, she is seeing two of everything. She pinches herself hard, expecting to wake up from a nightmare. To her horror, this is really happening! She excuses herself and runs out of class to see the nurse. The school nurse tells Sallie the she has diplopia. As if being a freshman wasn't hard enough!

Defining Diplopia

Diplopia is a medical term for seeing two of a single object. There are two types of diplopia: monocular and binocular. Monocular diplopia affects only one eye, and binocular is a problem with the alignment of both eyes. Double vision can be a symptom of different eye problems, such as strabismus (crossed-eyes), or it can happen after an accident, like a head injury. Diplopia may be a symptom of something minor, or it could be a major health concern, so it is important to seek medical advice if you are experiencing double vision.


Monocular diplopia is caused by a structural defect in the eye. In this case, the light from a single image is split in two because of a defect in the eye. Cataracts are a common cause of this type of double vision. If cataracts are present, they are easily correctable with minor surgery. Monocular diplopia can also be caused by astigmatism, corneal scars, and corneal shape problems.

Binocular diplopia occurs when both eyes cannot focus on the same object you are viewing. This is called ocular misalignment. Normally, each of your eyes looks at a single object and that image is fused into one picture by your brain. When your eyes cannot focus on the same thing, then the image may appear double. Muscle problems affecting the eyes can cause this type of diplopia, such as myasthenia gravis and Graves' disease. Conditions that cause nerve damage, such as diabetes, multiple sclerosis, and Guillain-Barre syndrome, can also cause binocular diplopia. Stroke, brain tumors, increased pressure inside the brain, and aneurysm are additional causes.


Treatment of diplopia involves diagnosing and treating the underlying cause. For example, if cataracts are causing your double vision, then correcting this will improve your vision. There are some cases where diplopia cannot be reversed. Luckily, there are treatment options available to help you live with double vision. These include:

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