A
corrective lens is a
lens worn in front of the
eye, mainly used to treat
myopia,
hyperopia,
astigmatism, and
presbyopia.
Glasses or "spectacles" are worn on the face a short distance in front of the eye.
Contact lenses are worn directly on the surface of the eye.
Intraocular lenses are surgically implanted most commonly after
cataract removal, but recently for purely refractive purposes. Myopia (near-sightedness) requires a divergent lens, whereas hyperopia (far-sightedness) requires a convergent lens.