Contact lens and method of making same

Claim 1

The method of making a multifocal contact lens which comprises the steps of: providing a lens blank having a concave posterior surface shaped in conformity with a user's cornea; rotating the lens blank about an axis substantially coincidental with the optical axis of the user's eye as defined by the posterior surface; cutting a convex frst corrective surface on the anterior surface of the lens blank while the lens blank is being rotated about the rotation axis and in such relation to the posterior surface as to determine the maximum thickness of the contact lens to be produced until the first corrective surface provides a power for that surface conforming with the nearest distance correction of the user's prescription and thereby produces a focal point for the initial corrective surface lying substantially on the optical axis of the patient's eye; shifting the lens blank perpendicularly tp the axis of rotation in offset relation thereto; and cutting a convex second corrective surface on the anterior surface of the lens blank having the first corrective surface thereon while the lens blank is being rotated about the rotation axis until the second corrective surface provides a power for that surface conforming to a distance correction of the user's prescription to remove a portion of the first corrective surface and blend therewith at a point beginning substantially corresponding to the distance of the offset relation to leave a generally crescent-shaped first corrective surface zone surmounted by the second corrective surface zone in which the center of curvature of the second corrective zone lies adjacent to the focal point of the first corrective zone but offset therefrom by said offset relation.

Claim 2

The method of making a multifocal contact lens which comprises the steps of: providing a lens blank having a concave posterior surface shaped in conformity with a user's cornea; rotating the lens blank about an axis substantially coincidental with the optical axis of the user's eye as defined by the posterior surface; cutting a convex frst corrective surface on the anterior surface of the lens blank while the lens blank is being rotated about the rotation axis and in such relation to the posterior surface as to determine the maximum thickness of the contact lens to be produced until the first corrective surface provides a power for that surface conforming with the nearest distance correction of the user's prescription and thereby produces a focal point for the initial corrective surface lying substantially on the optical axis of the patient's eye; shifting the lens blank perpendicularly tp the axis of rotation in offset relation thereto; and cutting a convex second corrective surface on the anterior surface of the lens blank having the first corrective surface thereon while the lens blank is being rotated about the rotation axis until the second corrective surface provides a power for that surface conforming to a distance correction of the user's prescription to remove a portion of the first corrective surface and blend therewith at a point beginning substantially corresponding to the distance of the offset relation to leave a generally crescent-shaped first corrective surface zone surmounted by the second corrective surface zone in which the center of curvature of the second corrective zone lies adjacent to the focal point of the first corrective zone but offset therefrom by said offset relation.