Optics: eye examining – vision testing and correcting – Spectacles and eyeglasses – Ophthalmic lenses or blanks
Patent
1979-04-17
1981-11-24
Corbin, John K.
Optics: eye examining, vision testing and correcting
Spectacles and eyeglasses
Ophthalmic lenses or blanks
G02C 704
Patent
active
043020810
ABSTRACT:
A bifocal contact lens having a principal, distant vision body portion made from a material having a first index of refraction, and a bifocal segment fused in place at least partially within the body and formed from a material having a second index of refraction higher than the first index. The lens has an arcuate lower bifocal segment surface lying generally parallel to the outer edge of the lens body and terminating at a pair of outer end portions which are spaced from each other by a first included angle. The upper bifocal segment surface has at least three elements including a first, radially inner partially circular surface element disposed generally inwardly of the lens, and terminating at a pair of inner end portions spaced from each other by a second included angle. The second and third upper bifocal segment surface elements extend respectively between the outer and inner end portions, with the included angles being less than 170.degree., and the first included angle being no larger than the second included angle. The uppermost portion of the segment surface thus lies below the center of the lens and the second and third surfaces extend at least partially downwardly from the inner end portions when the lens is oriented to its intended position of use.
REFERENCES:
patent: 3684357 (1972-08-01), Tsuetaki
Encyclopedia of Contact Lens Practice; vol. II, Supplement 7, Chapter XXXI; Nov. 15, 1960; p. 37.
Kendall, C. A.; "Ultrafocal.RTM. Bifocal Contact Lens", Contacto, Jan. 1976, pp. 31-35.
Corbin John K.
Fitzgibbon James T.
Sugarman Scott J.
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