The eye can be compared to a camera. Light passes through the cornea, which begins the process of bending (refracting) the light rays. It then passes through the pupil, which is a round opening in the centre of the iris beyond which it travels through the lens. The lens bends the light rays further in order to focus them on the retina.
If the image is not focused, the retina receives a blurred image, and the eye is said to have a ‘refractive error’. The majority of adults in the UK wear glasses or contact lenses to correct such errors, which include short-sight, long-sight and astigmatism.
Another reason people need to wear glasses, typically over the age of 40, is to help reading in order to counteract presbyopia.
Many patients are used to wearing their glasses and do not want to stop. However, for those who wish to reduce their dependency on spectacles or contact lenses, techniques have improved such that surgery is a safer and better option than ever before.