05073021 is referenced by 113 patents and cites 12 patents.

A dual focal length ophthalmic lens is formed from a birefringent material with its fast and slow axes perpendicular to the user's visual axis. The dual focal property arises due to the differing indices of refraction of the birefringent material for light polarized parallel to the fast and slow axes. Light emanating from far objects having one polarization and light emanating from near objects having the opposite polarization are both focused onto the user's retina. Depending upon which object is being viewed, an in-focus and a blurred image appear simultaneously on the user's retina. The ability of the user's eye/brain system to distinguish between the two images provides bifocal action from a single lens. The invention may take the form of a spectacle, contact, or intraocular implant lens.

Title
Bifocal ophthalmic lens constructed from birefringent material
Application Number
7/324827
Publication Number
5073021
Application Date
March 17, 1989
Publication Date
December 17, 1991
Inventor
Joseph C Marron
Brighton
MI, US
Agent
Krass & Young
Assignee
Environmental Research Institute of Michigan
MI, US
IPC
A61F 2/16
G02B 5/30
G02C 7/04
G02C 7/06
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