contact lens Lens worn on the cornea to aid defective vision. Invented in 1887, lenses were initially made of glass. Modern contact lenses, developed (1948) by Kevin Tuohy, are made of plastic. Hard (corneal) lenses cover the pupil and part of the cornea. They are usually gas-permeable (allowing oxygen to reach the cornea). Soft (hydrophilic) lenses cover the whole cornea and are hydrated in saline solution.

con·tact lens • n. a thin plastic lens placed directly on the surface of the eye to correct visual defects.