People need to wear glasses for different reasons. Some people are said to be short-sighted or myopic. This is due to the cornea being too steeply curved or the eye longer than normal.
Therefore, light rays fall in short of the retina - the area at the back of the eye that interprets the image - and results in blurred distance vision.
Other people are long-sighted or hyperopic because their cornea is too flat or the eye is too short. This means that the light rays focus too far beyond the retina.
Others have a condition where the cornea is oval shaped rather than spherical, called astigmatism. This produces two different focal points which can blur images at all distances.
Laser surgery to reshape the cornea can help to correct these problems.
Complications occur in less than 5% of cases, according to the Royal College of Ophthalmologists.
Some people have a problem with dry eyes in the months after surgery and artificial tear supplements might be needed in the long term.
Many patients have experienced glare or halo effects when night driving, particularly just after treatment. This is more likely the higher the correction that has been made, but is rarely severe.
In rare cases, excessive thinning of the eye wall can cause the shape of the eye to be unstable after treatment. Severe loss of vision is very unusual, but some patients could require corneal surgery or hard contact lenses to restore vision, it said.
