Multifocal ophthalmic lens with induced aperture

Abstract

Multifocal lenses are defined by nonconical aspheric optical surfaces. Various alternative surface shapes provide a central distance vision region surrounded by an optical step. The optical step has repidly increasing power in the radial direction which creates an induced aperture through which the cortical elements of the vision system are induced to concentrate. The induced aperture results in increased clarity in distance vision. Nonconical aspheric optical surfaces are defined to produce the desired optical power distributions. These surface functions are also provided in form of polynomial series for simplicity of use in computer driven lathes for shaping contact lenses. To allow increased manipulation of the defining functions additional elements such as conic terms are added. To improve near vision correction in some configurations, an annular near vision region extends radially outward from the optical step. To improve low light distance vision, power is reduced in the lens region outside the mesopic pupillary dimension. In alternative embodiments, the distance vision region and optical step are formed by cyclic functions. These have benefits in ease of manipulation to fit various specific user geometry requirements. In some configurations, an extended near vision region is used outside the optical step to improve near vision correction. The invention includes contact lenses, scleral lenses, intraocular lenses, and lenses impressed or surgically shaped within the corneal tissue as well as methods of designing and fitting these lenses. Although nominally positive power lenses are also within the present invention, negative lenses gain particular benefit due to decreased lens thickness at the lens perimeter and consequent reduced spherical aberration.

Description

[0001] related application [0002] This application claims priority to US Patent Application No. 09 / 657,562, filed September 8,2000. Background of the invention [0003] The present invention relates to a lens having more than one focal length. The provided methods and structures are applicable to near and spectacle lenses and other lenses used to correct human vision. [0004] Most vision correction lenses are designed to correct distance vision only—that is, have a unique focal length. When a person looks at an approaching object, the eyes adapt to the divergent light emanating from the approaching object rather than parallel light. The accommodation of the human eye results in a physical change in the shape of the lens in the eye. The curvature of the lens reconverges and focuses incident light diverging from approaching objects onto the retina. This accommodation increases the convergence of light waves by bending the lens surface more steeply, which in turn increases ...

AI Technical Summary

Problems solved by technology

[0011] Lenses made according to the above patents and methods reflect optical limitations caused

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