Double vision, which is referred to medically as ‘diplopia’, is a condition in which a person sees two images of one object. These double images are sometimes also called ‘ghost images’. The two images can be side by side (‘horizontal diplopia’), one on top of the other (‘vertical diplopia’), or both.
Double vision has many possible causes and can affect one or both eyes. The treatment largely depends on the cause, but a type of lenses called prism lenses in glasses are often used to treat the condition. If you suspect you have double vision but prefer to wear contacts, however, using prism lenses may not be possible.
What causes diplopia, and how can you fix it?
Several conditions can lead to double vision, including problems that affect the cornea (the transparent, front part of the eye), lens, or nerves and muscles that control eye function.1
Double vision affects your ability to read and drive. It can also make movement challenging and potentially unsafe because you may have difficulty keeping your balance.
Prism correction in glasses can help some people with diplopia. The prism in the lens bends the light and aligns the two images so that the eye sees only one image.2
Prism correction is only suitable for some types of double vision, however. Diplopia caused by eye muscle imbalance such as strabismus (squint), nerve-related problems such as diabetes or multiple sclerosis, and brain issues such as migraine, tumour, or stroke can benefit from prism therapy.2
Can you alleviate double vision with contact lenses?
Unfortunately, in most situations, a prism cannot be incorporated into contact lenses.3 In certain unique situations, it may be possible to correct minor vertical misalignment with contacts. However, for the most part, people with double vision need to wear prescription glasses with prism correction. If your double vision is caused by a squint, it may be possible to use contacts again after corrective surgery.3
Who can wear prism contact lenses?
Some people can successfully correct their double vision with custom-built, gas-permeable prism contact lenses. These contacts have a special base-down, prism ballast design, similar to that of toric contact lenses.4 Toric lenses are prescribed to people with astigmatism and require rotational stability to provide consistent vision, as lenses float on a thin film of tears so can rotate once they are in place. A prism ballast design is a common stabilising technique used in toric contacts and prism contact lenses for double vision.
Who can’t wear prism contact lenses?
It is worth noting that only certain types of double vision can be corrected with prism contact lenses. They are successful in correcting binocular vertical imbalance, which is when the double vision affects both eyes and one image appears above the other.4 Customised gas-permeable prism contact lenses can be used to correct diplopia due to squint from a variety of causes, including eye muscle paralysis, tumour, and scleral buckle surgery.4 However, people with double vision due to other causes may not be suitable candidates for prism contact lenses and may need to wear glasses with prism lenses.
What to do if you’re seeing double when wearing contact lenses
If you are experiencing problems with double vision while wearing your contacts, it is very important to see your eye care professional as soon as possible. The causes of double vision may be benign and easily corrected through the use of prism lenses. On the other hand, your double vision could be a symptom of a more serious underlying problem such as a stroke, aneurysm, or brain tumour that requires emergency care.
If you are experiencing double vision, book an appointment with a Specsavers optician to see if this can be corrected with prism contact lenses. You can also browse our contact lenses page for more information about the various types of contacts available.
1. Stanford Health Care. (no date). Causes of Double Vision. [Online]. Available at: https://stanfordhealthcare.org... [Accessed 8 November 2019].
2. American Academy of Ophthalmology. (no date). What is Prism Correction in Eyeglasses? [Online]. Available at: https://www.aao.org/eye-health... [Accessed 8 November 2019].
3. American Academy of Ophthalmology. (no date). Can I have prism correction built into my contact lenses? [Online]. Available at: https://www.aao.org/eye-health/ask-ophthalmologist-q/can-i-have-prism-correction-built-into-my-contact- [Accessed 8 November 2019].
4. Engel WK, Rovick L, Wing E. Correction of binocular vertical diplopia with prism contact lens. JAAPOS. 2007 February. Volume 11, Issue 1, Page 88. [Online]. Available at: https://www.jaapos.org/article... [Accessed 8 November 2019].