MULTIFOCAL INTRAOCULAR LENSES FABRICATED FROM MEDIA EXHIBITING TUNED BIREFRINGENCE

Birefirngent lenses provide two simultaneous powers. One power is provided by ordinary rays, the other by extraordinary rays through the lens. Because the difference between the reading and distance powers of intraocular lenses is small when compared to the average lens power, the difference between the extraordinary and the ordinary index of refraction of birefringent intraocular lenses can also be small. It is shown that a single birefringent intraocular lens which is manufactured from a properly oriented polymeric lens material provides the two powers needed for distant viewing and reading. Compound lenses consisting of M birefringent lens components provide up to 2M powers within a desired interval. Degrees of freedom exist for the choic of power values inside the desired interval and for the intensities associated with the individual powers.