A near-sighted eye is usually longer than a normal-sighted eye.
Incoming rays of light are bundled so that their focal point is
not on, but in front of, the retina. Distant objects are
perceived in a blurred manner, whilst objects up close are in
focus. The longer the eye, the more pronounced the degree of
near-sightedness. The interactive animation to the side of this
text allows you to see how the eye and image perception change
with varying degrees of near-sightedness. The power of
refraction of the eyes can be reduced surgically by means of
laser correction or intraocular lenses, which shifts the focal
point backwards onto the retina. In the case of glasses or
contact lenses, this occurs by means of a concave lens, the
strength of which is expressed in minus dioptres.