What is Double Vision? Causes, Symptoms, Treatment, Prevention

People with double vision, also known as diplopia, often see two images of a single object instead of one — whether horizontal, vertical, or diagonal. 

Sometimes, double vision may result from an annoying but harmless condition known as strabismus. This condition is characterized by misaligned eyes.¹ 

More severe medical issues that can cause diplopia include:²

• Multiple sclerosis
• A brain tumor
• Giant cell arteritis
• Myasthenia gravis (weakening of the body's voluntary muscles)

Some people may mistake double vision for blurred vision. However, the two are different since blurry vision causes someone to see an unclear version of one object. 

What Is Temporary Double Vision?

Some people suffer from temporary double vision when recovering from LASIK or other vision correction surgery.⁵ 

This kind of diplopia usually goes away with time. In some cases, it must be addressed with advanced procedures such as laser surgery.

The following can cause this condition:

• Alcohol intoxication
• Opioids
• Benzodiazepines
• Some medications for seizures and epilepsy
• Concussions
• Head trauma
• Excessive tiredness
• Strained eyes 

The Different Types of Diplopia 

The two types of double vision include monocular diplopia and binocular diplopia. These form the basis of the initial examination during a doctor's visit. 

Understanding the kind of diplopia will help determine if the problem results from an issue in the brain or just within the eye.

Monocular Diplopia

Monocular diplopia or monocular double vision occurs when you experience double vision in only one eye. 

Even when the other eye is covered, the double vision persists. Looking in a different direction also does not eliminate the double vision.

Possible causes of monocular diplopia include:

• Cataract, which is prevalent among people above the age of 80 years³
• Issues with cornea shape, such as in the case of keratoconus or surface irregularity⁴ 
• Astigmatism and other refractive errors
• Dry eyes, whereby the eyes become itchy and stingy
• Lens dislocation, such as in the case of eye trauma
• Pterygium, which is the thickening of eye mucous membrane
• Polycoria, a condition where two pupils are present in the eye

Binocular Diplopia

Unlike monocular diplopia, binocular double vision affects both eyes and occurs only while both eyes are open. This is what eye care professionals consider “true” diplopia (as opposed to monocular diplopia).

Possible causes of binocular diplopia include: 

• Eye misalignment, which happens when the muscles around the eye are undeveloped, weak, or infected
• Strabismus or crossed eyes
• Diabetes can cause nerve damage in the eyes
• Extraocular muscle damage, such as in the case of head trauma, stroke, brain tumor, eye tumor, or multiple sclerosis
• Grave's disease (thyroid eye disease), which may cause thickening or swelling of eye socket muscles
• Myasthenia gravis, which affects eye muscles and hinders the ability of the eye muscles to work properly

What are the Symptoms of Double Vision?

The primary symptoms of double vision include:

• Having crossed eyes or "wandering eyes" 
• Pain when moving the eye
• Headache
• Droopy eyelids
• Nausea
• Weakness in the eyes

Watch out for the following symptoms in children:⁶

• Squinting to enhance vision
• Covering one eye with hands
• Unusual head positioning when looking at something
• Flicking the eyes side to side

Is Double Vision a Serious Condition?

The severity of double vision varies based on the cause. Even though short-term diplopia is not considered an emergency, early treatment is recommended. This is particularly true if the condition manifests after eye damage or infection. 

The sudden onset of diplopia (particularly binocular) is cause for concern. Seek an eye care professional right away.

Diplopia is a visual issue, but seeking treatment from an eye doctor isn't the only option. Consult the prescribing doctor if your double vision may be due to a medication's side effects.

However, any case of eye trauma should be addressed by an experienced ophthalmologist.

How to Fix Diplopia: Double Vision Treatment Options

Finding the cause of the double vision is the most important step before deciding on the type of treatment appropriate for you. 

Common treatment options for double vision include:

Corrective Lenses

You can use eyeglasses or customized contact lenses to correct diplopia. 

Prisms, for example, can be engraved into your eyeglass lenses to adjust your vision. When placed on one or both lenses, press-on prisms assist in realigning the eyes and eliminate temporary double vision. They can also be carved into the eyeglasses for permanent double vision.

Eye Patch or Cover

Double vision may be mitigated by covering one eye. While an eye cover may not be a long-term solution, it may help manage double vision until a more permanent solution is found.

Vision Therapy

If strained or weaker eye muscles are the cause of your visual issue, your doctor may recommend exercises to help you restore eye muscle strength. Your vision problems should improve as your muscles strengthen.

Surgery

Depending on the cause, surgery may be required to address any physical problems. 

People who have cataracts or other eye disorders will almost certainly need surgery at some point. The surgical procedure to address that issue should also correct any double vision.

In cases where the underlying problem is related to the muscles that control eye movement, surgical interventions may be considered to restore proper alignment.

Botulinum toxin (Botox) injections

Eye doctors can inject Botox into the eyes to relax the muscles in the case of binocular diplopia.⁹ The treatment can block the signals sent from the brain to certain muscles, reducing or eliminating double vision.

What are the Complications of Double Vision?

Double vision may result from something easy to treat to something more complex, such as a chronic illness. The altered field of vision may cause the following:

• Nausea
• Vertigo
• Light or sound sensitivity
• Eye strain
• Severe eye discomfort
• Visual alteration
• Headaches

While rare, double vision might stem from life-threatening conditions like infections or brain tumors.

Any headache accompanied by vision changes can be life-threatening and require urgent medical attention.

How to Tell if You Have Double Vision (Diagnosis)

The best way to detect monocular or binocular double vision is through a comprehensive eye exam from your eye doctor. 

When you go to the doctor, they'll note your symptoms and do a few tests to rule out any other visual issues. They will also do a quick test to determine the kind of diplopia you have.

Once you've been diagnosed with diplopia, the search for a cause follows. When searching for the cause, your doctor will do the following:

• Examine your current health status. Your doctor will discuss with you and take stock of the history of your symptoms, your personal health history, and that of your family.
• Conduct a physical exam. A comprehensive physical examination can assist your doctor in determining the cause of your double vision. This examination may include blood tests, vision checks, toxicity tests, blood sugar tests, and imaging (CT scan or MRI).
• MRI neuroimaging. Some patients may require MRI neuroimaging to identify abnormalities in the orbital, cranial, or central nervous systems (CNS).⁸ 

Many instances of double vision resolve on their own. However, a medical examination is recommended to keep track of the patient's condition and further establish the level of impairment.⁷

What is the Outlook for Double Vision?

People with double vision recover completely after some time, especially after addressing the underlying cause. 

Depending on the cause, some patients may recover with minimal therapy. However, others may need more medical attention to deal with the issue.

Some of the most common causes of double vision, such as cataracts and cranial nerve palsy, may reoccur. Consult your doctor as soon as it arises so treatment can begin at the earliest stages.

Can You Prevent Double Vision? 

You can prevent double vision if you prevent the occurrence of underlying problems. 

Here are some tips:

• Managing diabetes. Diabetes patients who stick to their treatment regimens have a reduced risk of developing double vision. People who observe a balanced diet and exercise regularly are far less likely to develop diabetes-related double vision. 
• Prevent cataract development. Wearing sunglasses, quitting smoking, and eating a balanced diet help keep your eyes healthy and prevent cataracts.
• Soothe dry eyes. Keep your eyes well-lubricated. Also, try to avoid eye strain caused by extended computer usage. This may contribute to dry eyes.
• Prevent head injuries. Wear your seatbelt, helmet, or appropriate protective gear in risky environments.

Summary

• Double vision or diplopia is a visual impairment that can have minor to severe symptoms
• There are various underlying causes of this condition, which can help determine the type of diplopia you have
• The best way to determine and treat double vision is to visit an eye specialist
• Treatment for double vision depends on the underlying cause and may range from medications to surgery