glossary

Transparent biconvex lens located behind the pupil; refracts light to focus images on the retina. The natural lens inside of the eye. Transparent, biconvex intraocular tissue that converges light to helps bring rays of light to the retina.

An enlargement of the cup or central depression in the optic nerve head. Cupping is visible when viewing the back of the eye with an ophthalmoscope. An enlarged cup especially if accompanied by a notch or a small spot of bleeding is a sign of glaucoma. Cupping is a clinical sign that indicates that a large number of nerve fibers in the optic nerve have been lost.

A substance which paralyses the ciliary muscle. It is usually necessary to use this to obtain an accurate measurement of refractive error in younger children.