Lens design method and resulting aspheric lens

• US 5,050,981 A
• Filed: 07/24/1990
• Issued: 09/24/1991
• Est. Priority Date: 07/24/1990
• Status: Expired due to Term

• Current Assignee: Johnson & Johnson Vision Products, Inc.
• Original Assignee: Johnson & Johnson Vision Products, Inc.
• Inventors: Roffman, Jeffrey H.
• Primary Examiner(s): Sugarman, Scott J.
• Application Number:
  US07/557,261
• Time in Patent Office: 427 Days
• Field of Search: 351/160 R, 351/160 H, 351/161, 351/162, 351/159, 351/167, 351/177
• US Class Current: 351/177
• CPC Class Codes: A61F 2/1637 Correcting aberrations caused by inhomogeneities; correcting intrinsic aberrations, e.g. of the cornea, of the surface of the natural lens, aspheric, cylindrical, toric lenses
• CPC Class Codes: A61F 2240/002 Designing or making customized prostheses
• CPC Class Codes: G02C 7/02 Lenses; Lens systems ; Methods of designing lenses
• CPC Class Codes: G02C 7/028 Special mathematical design techniques
• CPC Class Codes: G02C 7/04 Contact lenses for the eyes disinfection or sterilisation of contact lenses A61L12/00

Abstract

An aspheric lens for providing improved vision and a method for generating such a lens is described. The lens provides a sharp image focus while minimizing image aberrations. The method utilizes ray tracing techniques in conjunction with Modulation Transfer functions to accurately account for the total corrective lens-eye system. The lens may be in the form of a contact lens, an intraocular lens, a natural lens or a spectacle lens, and is suitable for correcting myopia, presbyopia, astigmatism and other focusing problems. The lens is characterized by a hyperbolic or parabolic surface which functions to reduce spherical aberrations and minimize the retinal image spot size.

Claims

1. A method of constructing a lens for focusing light on the retina of the eye comprising the steps of:

a) constructing a Fourier Transform function model that generates modulation transfer frequencies for the human eye and a preliminary lens, said lens having at least one rotationally symmetric surface defined by the equation;

##EQU4## where X is the aspheric surface point at position Y, r is the central radius, and κ

is commonly used aspheric constant, wherein the value of κ

is less than or equal to -1,

b) performing an analysis using the model so constructed to trace light ray paths through the lens-eye system,

c) varying the value of the aspheric constant, κ

, for the preliminary lens to achieve a lens-eye system with a trace of light ray paths optimized for sharpest focus by minimizing retinal spot size of said rays.

2. The method of claim 1 wherein the lens so constructed is a contact lens.

3. The method of claim 1 wherein the value of κ

is varied between about -1 and about 31 2 in optimizing the performance of the corrective lens-eye system.

4. The method of claim 1 wherein the modulation transfer frequency is compared to the diffraction limit to optimize the corrective lens-eye system.

5. The method of claim 1 wherein the eye in the corrective lens-eye system is emmetropic and the optimization process produces vision that exceeds that of the normal eye.

6. The method of claim 1 wherein the corrective lens-eye system is optimized by positioning the focused image closest to the retina.