Double Vision (Diplopia): Causes, Diagnosis, and Treatment

Double vision refers to seeing two images of one object at the same time. Duplicate images can manifest vertical to each other, horizontal or diagonal. You can have double vision, or diplopia, in one or both eyes. The primary cause of diplopia is a malfunction of the extraocular muscles.

Intro

Double vision is a condition that refers to seeing two images of one object at the same time. Duplicate images can appear vertical to each other, horizontal or diagonal. 

You can have double vision, also called diplopia, in one or both eyes. The primary cause of diplopia is a malfunction of the extraocular muscles.

Double vision occurs when problems in eye muscles or nerves cause the image to be focused on different locations on each retina. These problems may be the result of neuromuscular junction problems, mechanical problems, and cranial nerve disorders. 

Diplopia can be temporary or voluntary. Temporary diplopia may be caused by head injuries such as concussions, alcohol intoxication or strained/tired eye muscles. It can also be caused by the consumption of medications like opioids or benzodiazepines. 

Overfocusing on close objects or unfocusing on them can causes voluntary double vision.

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Types

There are two main types of double vision — monocular and binocular diplopia:

• Monocular diplopia is a double vision that occurs when viewing with only one eye. The additional image usually appears as a ghost.
• Binocular diplopia is a double vision that occurs when both your eyes are open. This type often disappears when either eye is covered. In these cases, while the fovea of one eye is directed towards an object, the fovea of the other eye is directed elsewhere. As a result, the object’s image falls outside the foveal area of your retina, triggering the perception of two images. 

Causes

Diplopia is largely caused by problems with the function of extraocular muscles.  Normally, your eye movements are coordinated, allowing images to be properly focused on your left and right retinas for single vision. 

Binocular diplopia can result from strabismus, a condition characterized by a misalignment of your eyes relative to each other. 

Other causes include uncorrected refractive problems, media problems, dry eye syndrome, cataracts, cornea shape problems, corneal scarring, eye muscle problems, unstable tear film, wrong eyeglasses, media opacities, intraocular lens decentration (misalignment) and uveitis.

Cranial nerve palsy, myasthenia gravis and orbital infiltration can also cause binocular diplopia.

Double vision can also signal the presence of a systemic disease, especially to a neurological or muscular process. Some of the neurological, ophthalmologic, autoimmune, infectious and neoplastic causes of diplopia include: 

• Strabismus
• Brain tumor
• Abscess
• Lasik complications
• Damaged cranial nerves
• Diabetes
• Hyperthyroidism
• Cancer
• Trauma
• Migraine headaches
• Sinusitis 
• Botulism
• Keratoconus
• Antipsychotic medication
• Fluoroquinolone antibiotics
• Multiple sclerosis
• Graves disease
• Lyme disease

Symptoms

Which symptoms of diplopia you experience depend on the type of diplopia you have. With double vision, the two images of a single object can appear next to each other in three ways — horizontally, vertically or diagonally.

If your eye misalignment is horizontal, the double image appears side by side. If the eye misalignment is vertical, one image appears on top of the other. Diagonally, the images are vertically and horizontally displaced from each other, giving an overlapping appearance. 

Double vision may only appear when you move your eyes in a certain direction, leading you to believe that you may not have diplopia. (You do.) 

Also, if you have diplopia, you may experience other symptoms, including:

• bacBlurry vision
• Headache
• Nausea
• Dizziness/vertigo
• Pain when moving your eye
• Pain around your eyes, like in your eyebrows or temple
• Misalignment of one or both eyes (a cross-eye or wandering eye look)
• Droopy eyelids

Diagnosis

When eye doctors diagnose diplopia, they rely primarily on information from the person affected by the condition. That includes a medical history, a history of symptoms and an update on current symptoms.

The doctor first determines the type of double vision, then moves to potential causes and treatment options. When looking for causes, doctors have tests they use.

Two tests are an extraocular motility test and an ocular alignment test, both of which help determine if the diplopia is caused by cranial nerve palsy. Eye doctors also conduct physical examinations, computed tomography (CT) scans, blood tests, and magnetic resonance imaging (MRI) scans to determine the underlying cause.

Treatment

Treatment options for diplopia are limited and depend on the conditions producing the double vision symptoms. Doctors first want to identify the underlying cause before they pick a treatment plan.

For monocular diplopia, possible treatment options include correcting refractive errors, eye exercises, and possible cataract surgery.

For binocular diplopia, an eye doctor may palliate double vision using prisms in your eyeglasses. This method is usually effective if you have small misalignments. If you have large misalignments, doctors often op for treatment with tape or a patch to cover the affected eye.

Monovision correction is also a viable treatment option if you have binocular diplopia with small misalignments. Monovision correction involves wearing a contact lens in one eye, thus making that eye myopic or hyperopic to disrupt binocular viewing.

Doctors also consider surgery to correct double vision resulting from strabismus. It may also be the best option if you do not experience any improvements following non-surgical therapies.

Strabismus surgery has proved successful in improving double vision. Eye alignment surgery is usually an outpatient procedure performed under general anesthesia.

During the procedure, the surgeon either tightens or loosens your extraocular muscles to strengthen or weaken them, respectively. These techniques change the alignment of your eyes. The procedures may involve a recession, transposition, resection or plication.

Doctors also turn to Botulinum toxin an effective treatment option for reducing diplopia. However, this not always preferred. Doctors cannot predict how someone will react to specific doses of botulinum toxin.

The effects of the toxin are also not permanent, leading to multiple treatments.

Prevention

The prevention of diplopia is variable and depends on the underlying condition that causes the double vision. Prevention involves preventing the conditions or diseases that may cause diplopia. As such, patient education on the nature of diplopia is essential since preventing diplopia, especially binocular diplopia, can be challenging. 

If you experience any of the symptoms of diplopia, it is advisable to visit a specialist such as an ophthalmologist or neuro-ophthalmologist for early diagnosis and treatment. This is because the workup of diplopia may be beyond the scope of primary caregivers.

When to See a Doctor

Diplopia, and particularly binocular diplopia, can be one of the first signs of a serious condition, including trauma, stroke, aneurysm, neoplasm, and infections, among others. 

As such, eye doctors recommend you visit them if you experience symptoms such as ocular pain, headaches and unilateral pupil dilation. These and other can impact your quality of life, affect your movement, balance and ability to engage in certain important activities such as driving or reading.

FAQs

What can cause your vision to see double?

Double vision occurs when problems with your eye muscles or nerves cause the image of an object to be focused on different places on each of your retinas. 

Double vision has many causes, including local problems affecting your eye, eye muscles, and cranial nerves. It can also be the result of a wide range of systemic diseases and conditions such as autoimmune diseases, infections, trauma, diabetes, multiple sclerosis, and hyperthyroidism. 

Is sudden double vision serious?

Yes. Sudden double vision may be indicative of a serious or even life-threatening condition such as a stroke, aneurysm or trauma that requires immediate medical attention.

Does double vision go away?

Double vision can go away depending on the type and the underlying condition causing it. The prognosis depends on the cause. 

Treatment of the underlying causes of monocular and binocular diplopia often improves outcomes for these types of double vision. Temporary and voluntary diplopia conditions are usually not serious and resolve quickly with no known long-term effects.

References

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2. Deciphering Diplopia. (December 2009). American Academy of Ophthalmology.

3. Diplopia. (May 2021). MERCK MANUAL Professional Version.

4. Diplopia (July 2006). The Neurologist.

5. Recent Advances Clarifying the Etiologies of Strabismus. (June 2016). Journal of the North American Neuro-ophthalmology Society.

6. Diplopia and Fluoroquinolones. (July 2009). Ophthalmology.

7. Acute binocular diplopia: peripheral or central? (August 2020). Journal of Neurology.

8. Monovision correction for small-angle diplopia. (September 2012). National Center for Biotechnology Information.

9. The Role of Botulinum Toxin in the Treatment of Strabismus. (June 2019). National Center for Biotechnology Information.

10. Double Vision. (November 2015). The British Medical Journal.