What causes double vision?

20 Sep What causes double vision?

Double vision, also known as diplopia, is the perception of two overlapping or separate images of a single object when you should only be seeing one image. This eye condition can affect your balance and ability to read.

There are two main types of diplopia: binocular and monocular.

Binocular double vision

What is it? 

Binocular double vision is usually related to the misalignment of the eyes. This type of double vision stops when either eye is covered. Binocular diplopia can be caused by any condition that affects the extraocular muscles, which are the muscles that control the direction of your gaze.

What are the causes?

Below are some of the most common causes of binocular diplopia:

1. Nerve damage. People may experience double vision when the nerves controlling the muscles around the eyeball are damaged (extraocular muscles). Injury to nerves can be caused by brain damage as a result of infection, head trauma, stroke, multiple sclerosis, brain tumour or trauma to the eye socket.
2. Diabetes. Diabetes can lead to various problems with nerves that control the movement of the eye muscles. Some people may experience double vision even before they are aware they have diabetes.
3. Graves’ disease.This is one of the most common causes of hyperthyroidism (an overactive thyroid). Graves’ disease can also cause double vision due to thickening and swelling of the muscles that control the eyeball.
4. Myasthenia gravis. Myasthenia gravis is a neuromuscular disease that causes muscles to become weak and tire easily.
5. Trauma to eye muscles. Extraocular muscles can be injured or damaged by facial trauma, especially fractures of the bones of the eye socket.
6. Strabismus. Strabismus is a condition that causes childhood misalignment of the eyes. It affects about 4 percent of kids younger than age 6 and may cause binocular diplopia.

Monocular double vision

What is it?

This is when double vision occurs in only one eye. This means that the doubling does not go away even when you cover the other eye or look in different directions.

What are the causes?

1. Astigmatism. This is a condition where the front surface of the cornea is abnormally curved hence causing double vision.
2. Keratoconus. Keratoconus is a degenerative condition that causes the cornea to gradually become cone-shaped and thin.
3. Pterygium. This is thickening and hardening of the conjunctiva causing it to extend to the cornea and cause double vision.
4. Dry eyes.The eye dries out too quickly or does not produce enough tears.
5. Retinal abnormalities. For example, in macular degeneration, the centre of the field of vision gradually disappears, and if there’s swelling, double vision can occur in one eye.
6. Cataracts. Cataracts in the eyes can also cause diplopia in one eye.

Double vision treatments

Treatment for double vision usually depends on the underlying condition(s) that caused it. 

People experiencing monocular double vision due to suffering from astigmatism may be recommended different options. Depending on their personal situations, an eye expert may suggest:

• Wearing contact lenses or corrective glasses which corrects the passage light and helps realign the image. 
• Considering laser eye surgery which will reshape the cornea.

For people suffering from cataracts and experiencing monocular double vision, one of the best treatment options is cataract surgery which resolves the condition by removing clouding in the eye.

For people experiencing binocular diplopia, the most common treatments include: eye exercises, wearing glasses, wearing opaque contact lenses, wearing an eye patch, vision therapy, medications, and surgery to correct muscle positioning.

Important note:  Temporary episodes of diplopia can occur for many different reasons, including being overly tired or consuming too much alcohol. This type of temporary diplopia is usually no major cause for worry. However, if diplopia keeps coming back or is long lasting, it can be a symptom of serious health problems. Therefore, it’s extremely important to see an eye doctor physician immediately if you start experiencing diplopia.

References:

1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5710033/ 
2. https://www.webmd.com/eye-health/double-vision-diplopia-causes-symptoms-diagnosis-treatment 
3. https://stanfordhealthcare.org/medical-conditions/eyes-and-vision/double-vision/causes.html 
4. https://www.epocrates.com/sites/default/files/res/dacc/2016/DiplopiaDoubleVisionBMJ1603.pdf 
5. https://jnnp.bmj.com/content/jnnp/75/suppl_4/iv24.full.pdf 
6. https://neurology.uams.edu/wp-content/uploads/sites/49/2018/03/diplopia-evaluation-humaira.pdf 

This article is not a substitute for a consultation with your surgeon. Before choosing to proceed with laser eye surgery your surgeon will have a detailed discussion with you about the right procedure and about the potential complications.

Dr. Ron Binetter

A unique mix of expertise, experience and international reputation, Dr Ron Binetter is the figure behind the Binetter Eye Centre. With more than two decades of hands-on experience in eye surgery, Dr Binetter is a specialist in cataract, lens implantation and laser eye surgery. Learn more about Dr Ron Binetter’s background and qualifications.