Optics: eye examining – vision testing and correcting – Spectacles and eyeglasses – Ophthalmic lenses or blanks
Patent
1987-12-16
1989-09-26
Sugarman, Scott J.
Optics: eye examining, vision testing and correcting
Spectacles and eyeglasses
Ophthalmic lenses or blanks
G02C 704
Patent
active
048695874
ABSTRACT:
Disclosed is a multifocal contact lens of the concentric simultaneous vision type. A bifocal embodiment of the lens includes a central, near portion and an outer surrounding, distant portion. The lens body has a circular outer periphery and the near and distant portions are concentrically arranged on the lens body. The lens includes a prism ballast weighting at a lower edge and has a posterior curve fitted to the wearer's eye so that the lens is low-riding. The center of the near portion of the lens is offset below the center of the wearer's pupil leaving a crescent-shaped portion of the pupil covered by the distant rather than the near portion of the lens. In another embodiment, the lens is provided with a central distant portion of reduced size which, when downwardly offset with respect to the wearer's pupil, overlies a generally ovoid portion thereof. A trifocal embodiment of the lens includes a central portion having a first optical prescription, an outer annular portion having a second optical prescription, and an intermediate annular portion having an intermediate optical prescription. The central portion may provide either near or distant power correction, with the outer portion providing distant or near power correction, respectively. The central, outer and intermediate portions are preferably formed of the same material homogeneous throughout the lens body. Also disclosed is an outer annular fitting portion having a diameter of size approximately equal to that of the wearer's cornea for maintaining the inner concentric, optical correction portions of the lens with respect to the wearer's pupil.
REFERENCES:
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Mandell, R. B., Contact Lens Practice; Hard and Flexible Lenses; Charles C. Thomas; Springfield, Ill., pp. 649-679 (2nd Edition).
Kendell, C. A.; "Ultrafocal Bifocal Contact Lens"; Contacto; Jan. 1976, pp. 31-35.
Bronstein, L.; "Reverse Centrad Bifocal Contact Lenses"; The Optometric Weekly; Jun. 20, 1968, pp. 45-48.
Breger, J. L.; "New Design Elements for a Gas-Permeable Bifocal"; Contacto; Jul. 1983; pp. 31-32.
Advertisement: University Optical Products Co., Alges (Hefilcon A) Bifocal Contact Lenses, copyright 1986.
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