MXPA00011631A - Contact lenses with contoured edges - Google Patents

Abstract

The invention provides contact lenses with contoured lens edges. The contoured lens edges of the invention form a substantially smooth curve (21). The lens edge comprises the area beginning at the periphery (18) of the optic zone (11) and ending at the outermost point (19) of the lens. The use of the contoured lens edge eliminates the need for one or more of a lenticular zone, bevel, side wall, or other zones found in a conventional contact lens to facilitate lens handling and comfort. The invention provides also a method for designing a contact lens comprising, consisting essentially of, and consisting of:a) designing an optic zone for a first lens surface;b) selecting an x and a y coordinate for each of at least two points on the first lens surface;and c) fitting a curve through the points specified in step b) to form a contoured lens edge, the contoured lens edge being a substantially smooth curve having a functional form selected from a group consisting of a polynomial, a ratio of two polynomials, a trigonometric function, a parametric function, a spline, a conic section, and combinations thereof.

Description

CONTACT LENSES WITH CONTOURED EDGES FIELD OF THE INVENTION The invention relates to contact lenses. In particular, the invention relates to contact lenses having contoured edges designs that improve lens handling and comfort.

BACKGROUND OF THE INVENTION The use of cosmetic contact lenses and contact lenses for the correction of visual acuity is well known. In general, the anterior, or convex, surface of a contact lens incorporates an optical zone, a lenticular zone, a bevel, and a side wall. The presence of all but the optical zone is necessary for the contact lens to fit comfortably, for the lens to be correctly positioned in the user's eye, and for the lens to be easily handled by the wearer of the lenses. However, the use of the lenticular zone, bevel and lateral wall is problematic. For example, the bevel forms a junction with the lenticular 2: one, which can act as a hinge point allowing the bevel to turn inward to, or out of, the user's eye. In addition, the joint can be rough enough to make it uncomfortable to wear the lenses.

The side wall can also cause discomfort to the user. Accordingly, there is a need for a lens that overcomes some of these disadvantages.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a partial and enlarged cross-sectional view of a lens illustrating a step in the method of the invention. Figure 2 is a partial and enlarged cross-sectional view of a lens illustrating another step in the method of the invention. Figure 3 is a partial and enlarged cross-sectional view of a lens illustrating another step in the method of the invention.

DETAILED DESCRIPTION OF THE INVENTION AND MODALITIES PREFERRED The invention provides contact lenses with contoured lens edges, and methods for producing contact lenses. The contoured lens edges of the invention form a substantially smooth curve. By "lens edge" is meant the area that starts at the periphery of the optical zone and ends at the outermost point of the lens. The use of the contoured lens edge eliminates the need for one or more of a lenticular zone, bevel, sidewall, or other areas found in a conventional contact lens to facilitate lens handling and orientation. In addition, because the contoured edge forms a smooth bond with the optical zone of the lens, the lens is more convenient to use than conventional lenses. Finally, the contoured lens edge of the invention is favorable because it provides greater volume towards the periphery of the lens than a bevel, helping to maintain the shape and orientation of the lens and facilitating lens handling. In one embodiment, the invention provides a contact lens comprising, consisting essentially of, and consisting of a convex surface and a concave surface, one or both surfaces consisting essentially of an optical zone and a contoured lens edge. Preferably, the contoured lens edge of the invention is located on the convex surface of the lens. Accordingly, in another embodiment, the invention provides a contact lens comprising, consisting essentially of, and consists of a convex surface and a concave surface, the convex surface consisting essentially of an optical zone and a contoured lens edge. In another embodiment, the invention provides a method for designing a contact lens comprising, consisting essentially of, and consisting of: a) designing an optical zone for a first lens surface; b) selecting an x coordinate and a y coordinate for each of at least two points on the first lens surface; and c) adjusting a curve through the points specified in step b) to form a contoured lens edge, the contoured lens edge being substantially curved A soft tftttfÉfMÉÉÉMUfiÜi that has a functional form selected from the group consisting of a polynomial, a ratio of two polynomials, a trigonometric function, a parametric function, a flexible ruler to draw curves, a conical section, and combinations thereof. 5 The contact lenses useful in the invention can be hard or soft lenses. Soft contact lenses, made of any suitable material for producing such lenses, are preferably used. The lenses of the invention may have any of a variety of corrective optical features incorporated in the surfaces. For example, the lens may have any or more of spherical, aspheric, bifocal, multifocal, prismatic or cylindrical corrections. These corrections may be on either the convex or concave surface or both. For example, the lens of the invention may be a soft thorax contact lens, which means that the contact lens has a cylindrical optical surface, or increase to correct the astigmatism of the user. In the method of the invention, the optical zone of the lens is designed, or its radius, diameter, shape factor, and center thickness are determined, using any known method. Suitable methods include, without limitation, the use of design computer programs commercially available. Typically, the optical zone is designed after the base curve for the opposite surface is determined. After the determination of the base curve, the optical zone will be designed from ÜHÜHJH ^^^^ Mi ^^^^^^, ^, ^^,,,,,, it- .n ..- way that the combination of the base curve and optical zone provide the desired refraction correction for the lens. Once the optical zone design is complete, the contoured lens edge is provided by first selecting points on the surface that has the optical zone and then adjusting a curve through the selected points. The x and y coordinates are specified for the selected points on the lens surface. One skilled in the art will recognize that at least two points must be specified for curve fitting effects. One of the points should be located at the periphery of the optical zone and one at the outermost point of the lens. Additional points can be used and one skilled in the art will recognize that the more points that are used, the more complex the shape of the contoured edge can be. However, lens production machinery and procedural limitations can limit the number of points that can be used. 15 Then a curve is adjusted through the selected points. The functional form of the curve can be a polynomial, a ratio of two polynomials, trigonometric, parametric, a flexible ruler to draw curves, a conical section, or a combination thereof. The specific function and locations of points used are preferably are selected to provide a substantially smooth curve and the desired local thickness. The curve fitting step can be carried out by any convenient method. For example, curve fitting can be carried out using known numerical interpolation methods. By way of Alternatively, the adjustment can be made using commercially available computer programs. With reference to Figure 1, an optical zone of convex surface 11 is illustrated, which is designed in relation to the base curve 12. The coordinates x and y for points 13 to 17, shown in Figure 2, are selected, the points 13 and 17 corresponding to the periphery of the optical zone 18 and the outermost point of the lens 19, respectively. A commercially available finite element analysis computer program can be used to select points 13 through 17 so that the lens thickness profile is optimized for handling and comfort. A polynomial shape curve is adjusted across the dots resulting in the substantially soft contoured lens edge 21 of the lens 10 shown in Figure 3. The lenses of the invention can be formed by any convenient means. For example, an optical cutting tool with a numerically controlled lathe can be used to form a metallic optical tool incorporating the contoured edge of the invention. The tool is then used to make convex surface molds which are then used, together with concave surface molds, to form the lens of the invention using a suitable liquid resin placed between the molds followed by compression and curing of the resin.

Those skilled in the art will understand that various other changes of the details of the described invention may be made. It is intended that said changes be included within the scope of the claimed invention. .ÉÜMÉMÉMI

Claims (20)

NOVELTY OF THE INVENTION CLAIMS

1. - A contact lens comprising a convex surface and a concave surface, one or both surfaces consisting essentially of an optical zone and a contoured lens edge.

2. The lens according to claim 1, further characterized in that the convex surface consists essentially of the optical zone and the edge of the contoured lens.

3. The lens according to claim 1, further characterized in that the lens is a soft contact lens.

4. The lens according to claim 2, further characterized in that the lens is a soft contact lens.

5- A method for designing a contact lens comprising the steps of: a) designing an optical zone for a first surface of the lens; b) selecting an x coordinate and a y coordinate for each of at least two points on the first surface of the lens; and c) adjusting a curve through the points specified in step b) to form a contoured lens edge, the contoured lens edge being a substantially smooth curve having a functional form selected from the group consisting of a polynomial, a of two polynomials, a trigonometric function, a u ^ + jaamto parametric function, a flexible rule to draw curves, a conical section and combinations thereof.

6. The method according to claim 5, further characterized in that the first surface of the lens is the surface 5 of the convex lens.

7. The method according to claim 5, further characterized in that one of at least two points is at the periphery of the optical zone and one of at least two points is at an outermost point of the lens.

8. The method according to claim 6, further characterized in that one of at least two points is at the periphery of the optical zone and one of at least two points is at an outermost point of the lens.

9. The method according to claim 5, further characterized in that the functional form of the curve is a polynomial.

10. The method according to claim 5, further characterized in that the functional form of the curve is a ratio of two polynomials.

11. The method according to claim 5, further characterized in that the functional form of the curve is a trigonometric function.

12. - The method according to claim 5, further characterized in that the functional form of the curve is a parametric function.

13. The method according to claim 5, further characterized in that the functional form of the curve is a flexible rule of plotting curves.

14. The method according to claim 5, further characterized in that the functional shape of the curve is a conical section.

15. The method according to claim 8, further characterized in that the functional form of the curve is a polynomial.

16. The method according to claim 8, further characterized in that the functional form of the curve is a ratio of two polynomials.

17. The method according to claim 8, further characterized in that the functional form of the curve is a trigonometric function.

18. The method according to claim 8, further characterized in that the functional form of the curve is a parametric function.

19. The method according to claim 8, further characterized in that the functional shape of the curve is a flexible rule of plotting curves.

20. - The method according to claim 8, further characterized in that the functional shape of the curve is a conical section. .UÜfi..MÉÉ áá