Mold for contact lens with non-rotationally symmetric rim or edge

Abstract

A mold for a front curve of an ophthalmic lens includes an inner region having a non-rotationally symmetric shape, an outer region having a rotationally symmetric shape, and a continuous middle region between the inner region and the outer region. A first portion of the middle region is in contact with the inner region, defining a non-rotationally symmetric rim or edge of a front surface of the ophthalmic lens. A second portion of the middle region is in contact with the outer region and is rotationally symmetrical.

Claims

1. A mold pair for forming a contact lens therebetween, the contact lens having a front surface and an opposing back surface that meet at a lens edge, comprising: a back mold having a convex, rotationally symmetric surface; a front mold having an inner region, an outer region and a middle region positioned between and connecting said inner and outer regions, wherein the front mold further comprises an inner region having a concave portion bounded by a continuous, non- circular, non-planar, rotationally non-symmetric outer peripheral edge, wherein the concave portion and outer peripheral edge are sized and shaped to define said front surface and lens edge of said contact lens; an outer region having a rotationally symmetric shape and which does not influence a shape of said contact lens, said outer region lying in a single plane and having a continuous, circular, rotationally symmetric inner periphery, wherein said inner periphery of said outer region does not intersect with said outer peripheral edge of said inner region; and a middle region positioned between and connecting the outer peripheral edge of the inner region and the inner periphery of said outer region, the middle region comprising a continuous two-dimensional variable surface; wherein said front and back molds are adapted to be positioned relative to one another such that the outer peripheral edge of said inner region of said front mold is in constant contact with said convex surface of said back mold, and a space between said front and back molds defines a shape of said contact lens to be formed.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The foregoing and other features and advantages of the invention will be apparent from the following, more particular description of preferred embodiments of the invention, as illustrated in the accompanying drawings.

(2) FIG. 1 is a perspective view of a known mold for a front curve of a contact lens. The mold results in a contact lens having a rotationally-symmetric rim or edge.

(3) FIG. 2 is a perspective view of an exemplary mold for a front curve of a contact lens according to an embodiment of the present invention, showing an inner region, and outer region, and a middle region or zone. The mold results in a front curve of the lens having a non-rotationally symmetric rim or edge.

(4) FIG. 3A is a cross-section side view of a mold for a front curve of a contact lens according to an embodiment of the present invention, which is affixed to a mold for a back curve of the contact lens. A middle region or zone of the front curve mold is shown. The resulting contact lens (circled) has a rim or edge that is circular, continuous, and non-planar.

(5) FIG. 3B is a top view of the molds of FIG. 3A with four cross sections AB, AC, AD, AE and illustrating the middle region or zone according to the present invention.

(6) FIG. 3C is a side view comparison of cross sections AB and AD to cross sections AC and AE of the molds of FIGS. 3A-B. The rim or edge of the contact lens does not lie in the same plane as shown by the dotted line.

(7) FIG. 4A is a top view of contact lens molds with the four cross sections AB, AC, AD, and AE and illustrating a middle region or zone according to the present invention. The resulting contact lens has a non-circular, continuous, and non-planar rim or edge.

(8) FIG. 4B is a side view comparison of cross-sections AB and AD to cross sections AC and AE of the molds of FIG. 4A. The rim or edge of the contact lens does not lie in the same plane as shown by the dotted line.

(9) FIG. 5A is a top view of contact lens molds with the four cross sections AB, AC, AD, and AE and illustrating a middle region or zone according to the present invention. The resulting contact lens has a non-circular, non-continuous, and non-planar rim or edge.

(10) FIG. 5B is a side view of cross sections AB and AD of the contact lens molds of FIG. 5A. FIG. 5C is a side view comparison of cross section AE to cross section AC of the molds of FIG. 5A. The rim or edge of the contact lens does not lie in the same plane as shown by the dotted line.

(11) FIG. 6A is a top view of contact lens molds with the four cross sections AB, AC, AD, and AE and illustrating a middle region or zone according to the present invention. The resulting contact lens has a non-circular, continuous, and planar rim or edge.

(12) FIG. 6B is a side view comparison of cross sections AB and AD to cross sections AC and AE of the molds of FIG. 6A. The rim or edge of the contact lens lies in the same plane as shown by the dotted line.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(13) A contact lens is defined by a front surface, a back surface or base curve and a rim or edge. For the purpose of the present invention, the shape of the rim or edge may be described by circularity, continuity, and planarity. A rim or edge is circular if the rim or edge projection onto a given plane is a circle, otherwise the rim or edge is non-circular. A rim or edge is continuous if the edge is a curve that may be classified as at least a class C1 curve. Continuous in this sense is defined as the shape being smooth and closed, which means that the slope, i.e. the first derivative of the curve is continuous, otherwise the rim or edge is discontinuous. A rim or edge is planar if it lies fully in a single plane, otherwise it is non-planar.

(14) The present invention relates to a mold for a front curve of an ophthalmic lens, such as a contact lens, that enables manufacture of a lens with a non-rotationally symmetric rim or edge. In particular, the front curve mold according to the present invention allows for the use of an existing soft-molded manufacturing process for soft contact lenses. The mold for the front curve according to the present invention has a middle region or zone that maintains surface continuity between different mold regions, while providing for a lens having a non-rotationally symmetric rim or edge. In exemplary embodiments, the front curve mold provides for a contact lens having rim or edge that is at least one of non-circular, non-continuous, non-planar, or any combination thereof.

(15) Referring now to FIG. 2, a front curve lens mold 200 according to the present invention comprises an inner region 205, which forms the front curve of the resulting lens, and an outer region 210, which does not form any part of the resulting lens. Inner region 205 has a non-rotationally symmetric shape and outer region 210 has a rotationally symmetric shape. Unlike the lens mold shown in FIG. 1, the inner region 205 and the outer region 210 do not intersect.

(16) According to the present invention, a middle region or zone 215 is located between the inner region 205 and the outer region 210. In order to ensure surface continuity of the mold 1) a first portion of middle region 215 is in contact with the inner region 205, thereby defining a non-rotationally symmetrical rim or edge 220, and 2) a second portion of middle region or zone 215 is in contact with the outer region 210 and defines a rotationally symmetric rim or edge 225.

(17) According to the present invention, the middle region or zone 215 does not have a known three-dimensional (3D) geometric form. Thus, the middle region 215 does not have a close form equation. Rather, the middle region 215 may be described as a two-dimensional (2D) variable surface with a geometry that varies by meridian. That is, the shape may be different in one or more cross-sections. Another way to define this middle region 215 is to define the two dimensional variable surface as the result of connecting the rotationally symmetric edge 225, which lies in a single plane, to the desired non-rotationally symmetrical lens edge geometry, for example, edge 220, which may be non circular, non planar and non continuous and connect these two edges with a line, a curve, a polynomial, or a combination of multiple curves that results in a variable surface that facilitates mold halves interaction, including mold insertion, molding and mold removal. Although cross-sections AB, AC, AD, and AE are illustrated in the figures, it will be understood that additional meridians may be used to describe the variable surface of the middle region. The shape of the portion of the middle region that contacts the inner region depends on the desired shape of a resulting lens rim or edge. In specific embodiments, the middle region may be defined by a line, a curve, a polynomial, or a combination of multiple curves in order to facilitate the molding process.

(18) Referring now to FIG. 3A, a side view of a portion of the front curve contact lens mold 300 according to the present invention and a back surface contact lens mold 303 is shown. Inner region 305 and outer region 310 of the front curve mold 300 are shown. The resulting contact lens located between the molds is circled. In this exemplary embodiment, middle region or zone 315 is a two-dimensional line. The contact lens has a rim or edge 320 that is circular, continuous, and non-planar.

(19) FIG. 3B is a top view of the molds 300, 303 shown in FIG. 3A, with middle region 315, lens rim 320, and cross sections AB, AC, AD, and AE illustrated.

(20) FIG. 3C shows side view comparisons of portions of cross sections AB & AD to cross sections AC & AE of the molds of FIGS. 3A-3B. The dotted line shows that the lens rim or edge 320 does not lie in a single plane.

(21) Referring now to FIG. 4A, a top view of front and back molds for a contact lens having a non-circular, continuous, and non-planar rim or edge 420 is shown. A middle region 415 of the front curve mold according to the present invention is shown, along with cross-sections AB, AC, AD, and AE.

(22) FIG. 4B shows side view comparisons of front curve contact lens mold 400 and back curve mold 403 for cross sections AB & AD to that of cross sections AC & AE of the molds of FIG. 4A. Inner region 405, outer region 410, and middle region or zone 415 of the front curve mold are shown. The dotted line shows that the lens rim or edge 420 of cross sections AB & AD is in a different plane than the lens rim or edge 420 of cross sections AC & AE due to the fact that the rim or edge is non-circular and non-planar.

(23) Referring now to FIG. 5A, a top view of front and back molds for a contact lens having a non-circular, non-continuous, and non-planar rim or edge 520 is shown. A middle region 515 according to the present invention is shown, along with cross-sections AB, AC, AD, and AE.

(24) FIG. 5B shows side view comparisons of front curve contact lens mold 500 and back curve contact lens mold 503 for cross sections AB & AD of FIG. 5A. Inner region 505, outer region 510, and middle region 515 are shown. FIG. 5C shows side view comparisons of cross section AE, to that of cross section AC both of FIG. 5A. The dotted line shows that the lens edge or rim 520 of cross section AC is in a different plane than the lens rim or edge 520 of cross section AE due to the fact that the rim or edge is non-circular, non-continuous, and non-planar.

(25) Referring now to FIG. 6A, a top view of molds for a contact lens having a non-circular, continuous, planar rim or edge 620 is shown. A middle region 615 of a front curve mold according to the present invention is shown, along with cross-sections AB, AC, AD, and AE.

(26) FIG. 6B shows side view comparisons of front curve contact lens mold 600 and back curve contact lens mold 603 for cross sections AB & AD to cross sections AC & AE of the molds FIG. 6A. Inner region 605, outer region 610, and middle region or zone 615 are shown. The dotted line shows that the lens edge or rim 620 of cross sections AB & AD is in the same plane as the lens rim or edge 620 of cross sections AC & AE due to the fact that the rim or edge of the contact lens is planar.

(27) Although shown and described is what is believed to be the most practical and preferred embodiments, it is apparent that departures from specific designs and methods described and shown will suggest themselves to those skilled in the art and may be used without departing from the spirit and scope of the invention. The present invention is not restricted to the particular constructions described and illustrated, but should be constructed to cohere with all modifications that may fall within the scope of the appended claims.