Glossary

astigmatism – condition in which the cornea curvature is shaped like an egg wherein light rays are focused at two points of the retina rather than one, resulting in blurred vision

contact lens – a thin, curved plastic or glass that is fitted over the cornea of the eye to correct various defects

cornea – the clear, dome-shaped outer covering of the eye that lies in front of the iris and pupil; the cornea lets light into the eye

daily wear – designed to be removed prior to sleeping

extended wear – designed for continuous overnight wear

silicone hydrogel – the unique molecular structure of this material has two distinctive paths that allow water to pass through the lens readily without reducing the material’s ability to transmit oxygen to the eye, this allows the lens to move freely on the eye and to keep more oxygen flowing to the cornea

soft contact lens – lens that contains 25% to 79% water and more comfortable and easy to use

spherical contact lens – lens in which both the inner and outer optical surfaces are portions of a sphere

toric lens – lens in which either or both of the optical surfaces have the effect of a cylindrical lens and typically in combination with the effect of a spherical lens