Double vision

What is double vision (diplopia)?

Medically referred to as diplopia, double vision is seeing two images of a single object. The images may be side by side, on top of one another, or a mixture of both. On some occasions, you may even see more than two images of the same object.
Depending on the cause, double vision can either be a temporary issue or a long-term condition. Seeing in double vision may cause you to become anxious, dizzy, disoriented and confused. You may even experience the same symptoms when your eyes are closed.
As with all other medical conditions, it is important to inform the DVLA if you regularly suffer from diplopia. Failure to disclose diplopia or any other medical condition, could result in a £1000 fine or prosecution, if you were to be involved in an accident. You can report diplopia [1] to the DVLA by clicking here.

What causes double vision?

We often take for granted the complex process that occurs for our eyes to be able to function smoothly.  Our double vision can affect either one eye (monocular diplopia) or both (binocular diplopia), which usually dictates which kind of treatment you’ll require.
Temporary moments of double vision can be caused by a blow to the head, drinking too much alcohol or extreme tiredness. This is short term and usually disappears quickly.
There are also a number of other conditions that can cause long-term double vision, these include:

Head/brain injuries

A head injury, tumour, swelling or aneurysm in the brain can cause sudden double vision, and will usually continue until the problem is treated. After an eye examination, you’ll be referred to a neurologist or neurosurgeon for more comprehensive tests and diagnosis. Brain injuries can lead to more health complications and may cause diplopia to be a reoccurring issue.

Cranial nerve palsies

Paralysis or loss of coordination of the muscles that control how the eyes work together can also cause double vision and can both be a result of cranial nerve palsy. Cranial nerve palsies can be caused by a number of things, such as: diabetes, a tumour, meningitis, high blood pressure, a head injury, a brain aneurysm or a blockage in an artery. A doctor will usually look at each underlying issue and look at ways of dealing with the condition upon diagnosis.

A Squint

A squint (strabismus is the medical term) refers to a condition in which your eyes point in different directions. This is usually because the muscles controlling your eyes are either too strong, in which case they are prevented from moving smoothly, or too weak, in which case they are unable to move. Not all squints cause double vision and they are particularly common in young children.

Abnormalities

Abnormalities of the eye’s lens due to cataracts, or the retina due to macular degeneration, as well as refractive surgeries to correct these conditions, can cause double vision. Vision usually goes back to normal after a patient has recovered.

Dry eyes

Dry eyes, particularly more severe conditions such as Sjogren’s syndrome, can cause ghost images. Eye drops can help this by reintroducing moisture into the eyes if they are not producing enough tears.

Corneal irregularities

Usually caused by astigmatism, the irregular shape of the cornea affects how light passes through the eye, resulting in images appearing blurry. People with minor astigmatism may not even notice a blurriness in their vision, whereas people with more procured astigmatism will need corrective lenses.

How is double vision treated?

As most double vision is the result of underlying issues, once these conditions are treated, your vision will usually balance out.
Double vision caused by dry eyes can be treated by regularly using eye drops. Standard eye drops such as Blink Intensive Care eye drops can be purchased from our site, but more intense dry eye may require eye drops prescribed by an optician or GP.
Double vision caused corneal irregularities (usually as a result of astigmatism) can be treated with a corrective lens. This can be either prescription glasses or toric contact lenses.
Double vision from brain or head inquires usually clear up quickly after the inquiry has been sustained. Depending on the inquiry, in some cases, the double vision may be a reoccurring issue.
Double vision caused by abnormalities such as cataracts may cause double vision immediately after surgery, but usually clear up quickly.

Sources

[1] GOV.UK. (2019). Diplopia (double vision) and driving. [online] Available at: https://www.gov.uk/diplopia-and-driving [Accessed 21 May 2019].

Quick links:

Do I need an eye test?
A guide to light sensitivity
A guide to cataracts