MYOPIA (short sightedness)

MYOPIA (short sightedness). A normal eye elongates (in the animation - not in reality) and so becomes myopic. A diverging (bi-concave) lens then drops in front of the eye, correcting the myopia. This animation is actually a simulation since the paths of the rays are computed, not drawn.

Myopia is a refractive error. The myopic eye is relatively too long (along its visual axis) for the converging power of its optics. Consequently it cannot focus distant (parallel) rays on the retina. Such rays converge in front of the retina (compare with hypermetropia). Close objects (producing diverging rays) are focused properly (hence short sighted). Myopia is corrected by using spectacles with diverging (concave) lenses.