Contact lens and process for fitting

a technology of contact lenses and fittings, applied in the field of contact lenses, can solve the problems of limited success, blue vision at near points, and the ability of the eye's natural lens, and achieve the effect of increasing the near power

US20030123024A1Inactive Publication Date: 2003-07-03DUNN STEPHEN A
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Patent Information

Authority / Receiving Office
US · United States
Patent Type
Applications(United States)
Current Assignee / Owner
Publication Date
2003-07-03
Estimated Expiration
Not applicable · inactive patent

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Abstract

A contact lens with a central region (10) that is optimally less than approximately 1.9 millimeters in diameter and that is preferably overcorrected by approximately 25% to 100% over the correction needed for reading. Unexpectedly, the central region (10) does not impair distance vision, but compensates for presbyopia and therefore alows a user to focus on objects within a range of near and intermediate distances. A method for fitting the contact lens is also provided.
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Description

[0001] This invention relates to a contact lens that restores the ability to focus on objects within a range of distances near to the user (referred to as "natural accommodation"), while retaining the ability to see distant objects. More specifically, this invention relates to a contact lens with a conventional spherical concave surface conforming to the curvature of the eye (base curve) and having a non-conventional convex surface (optic curve) combining spherical and non constant aspherical curvature resulting in an optical system that provides true monocular presbyopic correction (correction of presbyopia in each eye independently, instead of partial or full distance correction in one eye and partial or full near correction in the other) and restores the phenomenon of "natural accommodation." Additionally, the invention affords a methodology of fitting that substantially reduces the skill and experience required by the contact lens fitter to a very basic level while affording a h...

Examples

example 1

[0065] A Microturn 9000 three axis radius lathe with aspheric surface cutting capabilities has been used to make contact lenses according to the present invention with base curves of 8.6 millimeters wet (6.6 millimeters dry). The lenses were manufactured dry from Ocufilcon B (a 53% water content material) and were hydrated afterwards. Therefore compensating calculations were made to achieve the appropriate hydrated parameters, such as base curve, radial expansion, linear expansion, power changes due to changes in index of refraction caused by hydration. When hydrating Ocufilcon B, the linear expansion parameter is approximately 1.35, the radial expansion parameter is approximately 1.30, and the power change parameter is approximately 0.57. The settings for the various radii of curvature in the various zones (for dry manufacturing using Ocufilcon B) are shown in the following cutting charts:

1 Zone 1 2 3 4 CENTER 1.10 1.50 1.90 6.00 DIA. C.T. DIST. POWER 1.40 1.80 2.20 6.00 DIA. C.T. ...