Liquid crystal lens review.

Liquid crystal lenses are possibly the spectacle lenses of the future for presbyopic corrections. They present a variable refractive index which can be used to produce the necessary addition needed for presbyopia. The variability of the refractive index is due to the fact that these materials are optically anisotropic. This effect is obtained by the application of an electric or magnetic field through the liquid crystal layer. A review of the literature relating to the evolution, the preparation and the operation of these lenses is given. A discussion is also included of the practical problems and drawbacks, which at present limit their use, and possible solutions.