What is double vision?
Double vision occurs when you see objects duplicated in your vision rather than a single clear image of each object. The dual images can appear horizontally, vertically, or at a tilted angle. Double vision may be temporary or permanent. Double vision can be due to a number of different events or conditions ranging from a minor concern to one that is serious or life-threatening. The double vision medical term is diplopia.
Double vision may affect one eye or both. Double vision in one eye is monocular diplopia. It is usually due to problems with the eye’s optical system. For example, corneal scarring or cataracts may split or multiply the image you see. This kind of double vision affects each eye separately, but both eyes may have the same problem. For example, a cataract in each eye. Covering the eye with the problem will eliminate the double vision.
A major cause of double vision is misalignment of the eyes so that they cannot visually fuse the separate visual images. An eye muscle imbalance or uncorrected refractive (eyeglass) problem can be responsible. Double vision can occur in young children whose eyes are misaligned from birth. The infant brain does not tolerate diplopia so it involuntarily shuts off vision in one eye (amblyopia). Diplopia can also occur later in life if injury or disease affects the ability of the eye muscles to work together properly. Examples include head trauma and stroke.
Binocular diplopia is only present when both eyes are open. If you close one eye, the double vision goes away.
Some causes of double vision may be the earliest sign of a serious neurological condition. Serious double vision causes include brain tumors, stroke, and multiple sclerosis.
Because the causes of double vision are so varied and can range from minor to life-threatening, it is important to contact your healthcare provider promptly for diagnosis of your double vision and treatment of the underlying cause.
Occasionally, double vision can be a sign of a medical emergency. Seek immediate medical care (call 911) for double vision along with other serious symptoms, including sudden loss of or change in vision, sudden loss of coordination, change in level of consciousness or alertness, severe headache, sudden weakness or numbness on one side of the body, or eye pain.
Seek prompt medical care for diagnosis of the underlying cause of your double vision, or if your double vision is persistent or recurrent.
What other symptoms might occur with double vision?
Double vision may accompany other symptoms, which will vary depending on the underlying disease, disorder or condition.
Other eye or vision symptoms that may occur along with double vision
Double vision may accompany other symptoms affecting the eye or vision including:
Glare or halos seen around lights
Inability to move one or both eyes (gaze limitation)
Increased sensitivity to light
Poor nighttime vision
Proptosis (eye bulging, as seen in Graves’ disease)
- Red, sore eyes (bloodshot eyes)
Other symptoms that may occur along with double vision
Double vision may accompany symptoms related to other body systems including:
Serious symptoms that might indicate a life-threatening condition
In some cases, double vision may be a symptom of a life-threatening condition that should be immediately evaluated in an emergency setting. Seek immediate medical care (call 911) for any of these life-threatening symptoms:
Change in level of consciousness or alertness, such as passing out or unresponsiveness
Fixed, dilated pupil
Loss of muscle coordination
Sudden change in vision, loss of vision, or eye pain
- Sudden weakness or numbness on one side of the body
What causes double vision?
Double vision may be caused by a variety of underlying conditions or diseases. Some of these conditions, such as cataracts, are fairly common, particularly in older populations, while others may be serious or life-threatening in nature. It may appear in only one eye as a result of refractive errors that split or multiply the image.
More commonly, double vision results from a misalignment of the eyes (strabismus) that prevents both eyes from focusing equally on an object. Misalignment may be present from birth, occur as a result of injury to the brain or the eye area, or be caused by systemic diseases, including multiple sclerosis and diabetes. Alcohol and drugs can also cause temporary double vision.
Common causes of double vision
Double vision may be caused by conditions including:
Cataracts (clouding or loss of transparency in the lens of the eye)
Diabetes (chronic disease that affects your body’s ability to use sugar for energy)
Misalignment of the eyes
Multiple sclerosis (disease that affects the brain and spinal cord causing weakness, coordination, balance difficulties, and other problems)
- Severe refractive error, such as myopia (nearsightedness), hyperopia (farsightedness), or astigmatism (irregularly shaped cornea)
Serious or life-threatening causes of double vision
In some cases, double vision may be a symptom of a serious or life-threatening condition that should be immediately evaluated in an emergency setting. These include:
When should you see a doctor for double vision?
Causes of double vision can be very serious. Anyone experiencing double vision should see a doctor, even if it goes away. Make an appointment with your doctor as soon as possible for an evaluation.
Call 911 or go to your nearest emergency room for double vision when:
You have binocular diplopia, meaning the double vision is present when both eyes are open, but goes away when you close either eye.
You have eye pain or a bulging eye or eyes.
You have had recent head trauma or eye injury.
- You have neurological symptoms, such as clumsiness, headache, numbness, weakness, paralysis, vertigo, or problems swallowing, talking, understanding speech, or walking.
How do doctors diagnose the cause of double vision?
To diagnose the cause of double vision, your doctor will take a medical history, perform an exam, and possibly order tests. Questions your doctor may ask about your vision include:
When did you first notice your double vision?
Is the double vision constant or does it come and go?
Does the double vision occur when you look in a certain direction?
Is the double vision present in one eye or both eyes? What happens when you close one eye?
Are the double images beside each other or above and below each other?
Are you having any other symptoms, such as headache, eye pain, or dizziness?
Do you have any other known medical conditions?
- Are you currently taking any medications?
During the physical exam, your doctor will focus on your eyes and the nervous system. You may need to track objects with your eyes. Your doctor may also perform a complete eye exam by looking at the internal structures of the eye. Your doctor will likely evaluate your nervous system function as well. This may involve evaluating your gait, coordination, reflexes, and muscle strength.
Depending on the results, your doctor may refer you to an ophthalmologist or order testing. Tests may include:
Refraction to identify any uncorrected refractive error
Blood tests to check blood chemistry, thyroid hormone levels, and for signs of infection, inflammation, or autoimmune reactions
- Imaging exams of the eye sockets, brain, and spinal cord, including CT (computed tomography) and MRI (magnetic resonance imaging)
It is not always possible to diagnose an underlying cause or condition. If the problem persists and your provider is unable to determine a cause, seeking a second opinion may give you more information and answers.
How do you treat double vision?
Double vision is often due to refractive errors or imbalance in the eye muscles; these conditions are not serious and can be treated by corrective lenses or surgery. Uncorrected diplopia in infants and young children can cause poor vision in one eye (amblyopia). However, in some cases, double vision may be caused by serious, or even life-threatening, conditions.
If you experience double vision, contact your healthcare provider promptly to determine the underlying condition. Once the underlying cause is diagnosed, following your treatment plan can help you reduce the risk of potential complications including:
Loss of vision and blindness
Spread of cancer