Double vision (diplopia)
What is double vision (diplopia)?
Double vision is when a person sees two images of the same object some or all of the time. The two images may be vertically separated (one on top of the other) or horizontally separated (side by side) or both (oblique). It generally occurs when the eyes, which have previously worked together as a pair, are no longer able to do so because a squint (see squint page) has developed and the eyes are now out of alignment with each other, resulting in double vision. This may happen suddenly or over a period of time.
What causes double vision?
Double vision is normally the resulting symptom when one or more of the eye muscles or nerves have been weakened or damaged. This weakness or damage can be caused by a number of conditions. General investigations may need to be carried out to try to find the cause of the double vision.
What action should you take?
If you have double vision you should visit your own GP or optometrist as soon as possible for a referral to an orthoptist. If the double vision has occurred suddenly, e.g. you wake up with double vision, you are advised to attend your local eye casualty department.
What treatment is available?
If the double vision is present most of the time, it may be possible to use a Fresnel prism on the person's own glasses to join the double vision. A Fresnel prism is a special transparent plastic sheet which can be customized to fit any pair of glasses. If the person does not wear glasses, it is possible to obtain a pair of clear glasses. Where Fresnel prisms are not successful, it may be necessary to cover one eye in order to block out one of the double images, at least temporarily. Double vision may gradually resolve with time. If full recovery does not occur, surgery to correct the double vision may be considered.