Optics: eye examining – vision testing and correcting – Spectacles and eyeglasses – Ophthalmic lenses or blanks
Patent
1980-04-21
1985-06-25
Corbin, John K.
Optics: eye examining, vision testing and correcting
Spectacles and eyeglasses
Ophthalmic lenses or blanks
351161, G02C 704, G02C 706
Patent
active
045250430
ABSTRACT:
A contact lens whose posterior surface has three zones, a central, an intermediate and a peripheral. The anterior surface of the lens also has a central zone corresponding to the posterior central zone. The central zones of these surfaces form the optical zone of the lens. The posterior intermediate zone of the lens is aspheric with its radius of curvature increasing continuously from the central to the peripheral zones to cause the cornea to assume a more optimal shape. The chord diameter of the posterior central zone is equal to or less than the measured maximum radius of curvature of the central zone of the cornea and preferably larger than the largest measured diameter of the pupil of the eye of the patient. The radius of curvature of the posterior central zone is such that the difference between the sag depth of the posterior central zone of the lens and the sag depth of the corresponding corneal central zone having the greatest measured spherical radius of curvature is in the range of zero to 15 microns. The radius of curvature of the lens in conjunction with that of the posterior central zone, provides the wearer substantially normal distance vision. For the presbyope, the optical zone can be modified to provide normal near as well as distant vision. The peripheral zone is beveled to provide limbal clearance.
REFERENCES:
patent: Re25286 (1962-11-01), De Carle
patent: 3950082 (1976-04-01), Volk
patent: 4302081 (1981-11-01), Tsuetaki
patent: 4418991 (1983-12-01), Breger
Corbin John K.
Flickinger Don J.
Sugarman Scott J.
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