MXPA96000978A - Rotationalally stabilized contact lens and len stabilization methods - Google Patents

Abstract

The present invention relates to contact lenses, especially toric and bifocal, which are substantially rotationally stabilized and methods for stabilizing contact lenses. Contact lenses are stabilized with respect to rotation when placed on the eye, by providing the lens with a non-circular shape. In a preferred concept, a toric lens is rotationally stabilized by providing the lens with an oval shape. Methods for providing noncircular lenses that have adequate shapes to fit the patient's eye are also presented.

Description

ROTATIONALALLY STABILIZED CONTACT LENS AND LENS STABILIZATION METHODS BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates broadly to ophthalmic lenses that rotationally stabilize while the lenses are in their position within the ocular environment. More specifically, this invention relates to methods and designs for stabilizing toric contact lenses for the correction of astigmatism and multifocal contact lenses for the correction of presbyopia. 2. Description of the related technology The use of ophthalmic lenses, such as contact lenses, to correct vision is well known in this art. Many patients can be treated correctly with contact lenses that are substantially spherical and have uniform power, that is, contact lenses that are designed to fit a substantially spherical eye. However, some patients suffer from a condition known as astigmatism. An astigmatic patient has an eye with an irregular shape, this means that the eye is not spherical. These patients require specialized contact lenses, known as toric lenses.

A toric lens has a surface that is essentially a torus, this means that the lens has two cylindrical curvatures, whose axes are substantially oriented perpendicularly to each other. In order to correct the astigmatism properly, a toric lens must be oriented in the design position on the eye. In case the lens rotates slightly, either clockwise or counterclockwise with respect to the design orientation, the patient's vision will be affected substantially.

Additionally, some patients require lenses that provide more than one power. For example, elderly patients tend to require bifocal lenses that are capable of providing a certain power for a first reading region, and a second power for a second region for viewing distant objects. Therefore, in the case of toric lenses and some bifocal lenses, it is important to keep the lens in a specific position within the eye. Previous techniques for rotational stabilization of contact lenses include those published in "Contact Lens Practice", fourth edition, Robert Mandell, pp 661-2 (1988). Mandell publishes two general methods of stabilizing rotation: the ballast of the prism and the thinning of the upper and lower periphery. In the prism ballast method, Mandell states that the thicker (base) portion of the prism will move to a lower position, such as a result of gravity. A ballast lens of the prism may optionally include a lower truncation. Typically, the truncation is expected to remain in a horizontal position while the lens is in position over the patient's eye, so that it appears that the truncation is along the top or bottom of the lens when it is in position over the eye. Truncated lenses cause little rotational stability, because the truncation line of the lens can be above or below the margins of the eyelids. Additionally, truncated lenses cause discomfort to the patient due to increased abrasion between the lens and the eyelid. U.S. Patent No. 4,874,234, published October 17, 1989 by Wichterle and U.S. Patent No. 4,095,878, published June 20, 1978 by Fanti, publish methods on contact lenses stabilized by rotation involving the thinning of the periphery of the lens (ie, cutting techniques). Wichterle proposes adding weight to the desired part of the lens, so that the gravitational forces would keep the lens in its proper position. Fanti seeks to maintain rotational stability through the interaction of the eyelids with the thicker areas of the lens. However, thickened parts of a lens reduce oxygen permeability, which is necessary for good health of the cornea.

Additionally, unwanted changes in optical power may occur when the thickened area of the lens flexes to fit the eye (See generally, M.Remba, "Evaluating the Hydrasoft Toric", Contact Lens Forum, pp. 45-51 , March 1987). While several methods have been suggested for stabilizing a contact lens in a suitable position, the need for rotationally stabilized contact lenses and methods for stabilizing contact lenses that do not suffer from the disadvantages of prior technologies, such as inadequate stabilization, remain. , decreased oxygen permeability, variations in optical power and increased patient discomfort.

SUMMARY OF THE INVENTION An object of the invention is to provide a means for stabilizing an ophthalmic lens that requires stabilization within the ocular environment.

Another object of the invention is to provide a rotationally stabilized toric contact lens.

A further object of the invention is to provide a rotationally stabilized multifocal contact lens.

A further objective of the invention is to provide rotationally stabilized lenses and methods of stabilization of lenses that do not significantly increase the inhibition of the lens towards the penetration of oxygen into the cornea.

A further object of the invention is to provide rotationally stabilized lenses and lens stabilization methods, which do not require more complex adjustment and handling techniques.

A further objective of the invention is to provide rotationally stabilized lenses and lens stabilization methods, without modifying the power of the lens. A further object of the invention is to provide a method and design for comfortably fitting a rotationally stabilized lens having an oval edge in a plan view.

A concept of the invention is an ophthalmic lens that is rotationally stabilized when it is within the ocular environment, by means of the non-circular shape of the lens.

The dimensions of the lens are chosen in such a way that the lens is longer through a section that is desired to remain substantially horizontal when placed on the eye, and shorter through a section that is desired to remain substantially vertical when placed. over the eye. In a preferred concept, the invention is a toric contact lens having a substantially oval shape, This means that it has a long axis that is intended to remain substantially horizontal when placed over the eye, and a short axis that is intended to remain substantially vertical when placed over the eye. The short axis is substantially perpendicular to the long axis. Another concept of the invention is a method for stabilizing an ophthalmic lens in position on an eye, such that the lens does not rotate substantially when used. The method involves providing an ophthalmic lens with a non-circular shape, such that the blinking of the user's eyelid, together with the lens shape, keeps the lens in a substantially stable position on the eye, with respect to the rotation around it. of the center of the lens. In a preferred concept, the method involves providing a substantially oval shape to a toric contact lens to provide rotational stability. A further concept of the present invention is a method for providing a non-circular, rotationally stabilized lens that fits suitably to the patient's eye.

The lens has an inner portion designed to correct the patient's vision and an outer portion designed to rotationally stabilize the lens over the eye. The method includes providing the inner portion of vision correction, a first selected radius to fit suitably to the portion of the eye intended to be adjacent to said inner portion of the correction of the eye. the vision. The method also includes providing the outer portion of rotational stability, with a second radius selected to suitably fit the portion of the eye, which is intended to be adjacent to said outer portion of rotational stability.

A further concept of the present invention is a multifocal lens that is rotationally stabilized by a noncircular peripheral edge, preferably an oval seen from the plane. The preferred multifocal lens is a bifocal lens. In one concept, each of the focal areas lies outside the center of the lens, such that the center of each focal area is aligned with the optical axis of the eye.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a view of the plane, of a rotationally stabilized lens having a periphery defining an oval, seen from the plane.

Figure 2 is a plan view of a rotationally stabilized, oval toric lens along the entire lens surface.

Figure 3 is a view of the plane, of an oval, rotationally stabilized oval lens, having a central toric area with toric radii, corresponding to the axes of the oval.

Figure 4 is a view of the plane, of an oval toric lens, rotationally stabilized, having a central toric area with toric radii, which do not correspond to the axes of the oval.

Figure 5 is a view of the plane, of an oval, rotationally stabilized lens, which is incorrectly placed on the patient's eye.

Figure 6 is a view of the plane, of an oval, rotationally stabilized lens, which is in the desired orientation on the patient's eye.

Figure 7 is a view of the plane of a circular lens of prior technology on the eye of a patient.

Figure 8 is a sectional view of an oval, rotationally stabilized oval contact lens.

Figure 9 is the bottom view of the lens of Figure 8.

Figure 10 is a view from the upper plane of a bifocal, rotationally stabilized lens.

DESCRIPTION OF THE PREFERRED CONCEPTS i Current presentations on rotational stabilization can be used in a wide variety of contact lenses. However, rotational stabilization is desired especially in toric or multifocal contact lenses (for example bifocal). Toric lenses have more than one radius of curvature along the lens, in order to correct the patient's astigmatism (this means non-spherical aberrations of the patient's eye). Accordingly, in order to achieve the best vision, a toric lens must be properly placed over the patient's eye to correct aberrations in a localized area. Therefore, a toric lens will have a first radius of curvature "r" in one direction, and a second radius of curvature "r2" in a second direction, which is substantially perpendicular to the first direction. , as used here, means an equivalent radius of curvature, defined by a circle through two end points and an upper point on a curve, so for a curve, which is an arc of a circle, the radius equivalent is the radius of the circle, however, for a curve whose points do not completely correspond to the arc of a circle, the radius equivalent is defined as the radius of a circle that passes through the end points of the curve and a point that have the greatest distance perpendicular to the line between the end points of the curve, the radius equivalent of curvature, or simply the radius of curvature, as used here, approximates the surface defined by the curve. Rotational stability is of similar importance for multifocal contact lenses (eg, bifocals). For a single object, bifocal lenses provide two images, each at its own distance away from the eye. An incorrect alignment of these images, with respect to the visual axis of the eye causes the patient to see double images (this means diplopia) due to the parallax of the images. Over the eye, conventional lenses are placed temporarily (away from the nose) and inferiorly (below) the pupil of the eye and the visual axis (See in general, P. Erickson and M. Robboy, "Performance Characteristics of a Hydrophilic Concentric Bifocal Contact Lens ", Am. J. of Optometry & Phisiological Optics, vol. 62, no. 10, pp. 702-8 (1985)). Therefore, in order to inhibit or prevent diplopia, bifocal lenses must have the optical area displaced from the geometric center of the lens, such that the bifocal optic is aligned with the visual axis of the eye. Therefore, rotational stability is highly important in bifocal lenses that inhibit diplopia. The invention can be understood more easily, referring to the drawings. Figure 1 illustrates the view of the plane of a rotationally stabilized contact lens, having an oval shape of the edge of the periphery from the view of the plane, or top, with a first axis of length ua "and a second axis of length "b" The oval is defined by the edge or periphery of the lens in a view through the visual axis of the lens. Figures 2 to 4 illustrate a variety of rotationally stabilized toric lens designs, which are in accordance with the present invention. Figure 2 shows a lens that is toric along the entire surface of the lens. While the tori radii, xx and r2, are shown as corresponding to the axes of the edge of the oval, of length "a" and "b", this is not a requirement of the present invention.

Figure 3 illustrates a rotationally stabilized lens having a toric surface, exclusively in a central optical area of the lens. The tori radii of figure 3 correspond to the axes of the edge of the oval. Therefore, the toric radius of curvature "r ^ along the surface of the lens is aligned with the long axis" a "defined by the edge of the lens, while the toric radius of curvature" r2"is aligned with the short axis "b", as shown in figures 1 and 2. While this alignment of the toric spokes with the axes of the oval is suitable for patients who have the so-called astigmatism "against the rule" and "with the rule "(this means that the elongation is in a vertical or horizontal direction), said alignment is not a requirement for the invention.

Figure 4 shows an alternative concept, in which Toric spokes do not correspond to the axes of the edge of the oval. This concept is appropriate to correct vision in patients who have the so-called "oblique" astigmatism, a condition in which the eye has elongated areas, which do not correspond to the horizontal or vertical axes of the eye (with the vertical axis parallel to an axis). of bilateral symmetry of the body). Without taking into account the axes of the ocular astigmatism, a toric area of the lens is provided to correct the astigmatism, while the innovative, present oval peripheral edge of the lens keeps the toric area within an appropriate orientation on the eye to correct the astigmatism.

The characteristics of the dynamic rotational stabilization of the present invention can be understood by referring to figures 5 and 6. Figure 5 shows the oval contact lens 20 in an incorrect position on the eye of a patient. The upper eyelid 24 and the lower eyelid 28 are shown contacting the lens at positions 22 and 26, respectively. It is believed that during involuntary or reflex blinking, the upper eyelid imparts a downward force on one side of the lens at position 22, while the lower eyelid imparts a force upward on the other side of the lens at position 26. These forces cause the lens to rotate counter-clockwise, back to the position in which the long axis is substantially horizontal, while that the short axis is substantially vertical, as shown in Figure 6. (Note that it is believed that the upper eyelid provides most, if not all, of the rotation force). Therefore, any rotational disorientation of the lens places the lens in such a way that unbalanced forces are produced which act on the lens when the patient blinks. This imbalance of forces continues, causing the lens to rotate, until the lens returns to a correct orientation by means of the flickering forces.

As illustrated in Figure 6, when a lens is appropriately oriented on the eye, the forces acting on the lens are substantially balanced. This balance of forces prevents the lens from rotating to an undesired position. In the event that an external force causes the lens to temporarily rotate to a slightly misaligned position, as shown in Figure 5, the flickering of the patient's eyelids will impart forces, as shown in Figure 5, to automatically readjust. the position of the lens.

In contrast, Figure 7 illustrates a substantially circular lens of prior technologies. While the eyelids of a patient can impart forces on the lens during blinking, the forces will not inhibit or promote lens rotation. As can be predicted in figure 7, without Any importance of the rotational orientation around the center of the lens, the force exerted by the eyelids 44 and 48 will be located centrally on the lens, at or near positions 42 and 46, respectively. Blinking forces that are located centrally will not cause any rotation or reorientation of the lens when the lens is in an incorrect rotational position. Therefore, small external forces on said circular lenses of previous technologies can cause the lens to rotate into an undesirable position, and blinking will not correct this disorientation.

As mentioned above, previous attempts to impart rotational stability included the thickening of the lens in some region, said region being found in the lower part of the eye. However, this prior technology of thickening techniques has problems, which include patient discomfort, undesirable power variations, and decreased oxygen permeability in the thickened regions. In contrast, the present invention avoids thickening or truncation of the lens, and therefore avoids the problems associated with these methods. Therefore, a concept of the present invention is a rotationally stabilized contact lens, having a non-circular shape defined by the edge of the lens in a view of the plane or upper, in which the lens has a first 11 dimension in a first cross section of the lens, and a second dimension in a second cross section of the lens. The first cross section is substantially perpendicular to the second cross section, both cross sections being perpendicular to the plane defined by the periphery of the edge from a plane view. The first dimension is longer than the second dimension, such that the lens remains substantially rotationally stable when placed over the patient's eye. When being on the eye, the lens maintains a position with the cross section having the first longest dimension remaining substantially horizontal, and the second dimension with a second shorter dimension remaining substantially vertical.

The peripheral shape of the lens (defined by the edge of the lens) can be chosen from a wide variety of shapes having the long and short sections as described above. For example, the lens may have a substantially rectangular shape, a rectangular shape with rounded edges or an oval shape. The preferred shape of the lens is oval. Additionally, it is not a requirement of this invention that the edge of the lens is on a single plane. The oval shape of the edge is defined by a perspective that looks down, this means through the axis of vision of the lens (view of the plane or higher).

The preferred rotationally stabilized oval shaped contact lens of the present invention has a peripheral edge defining an oval shape (from a plan view) with a long axis in a first direction, and a short axis in a second direction which is substantially perpendicular to the first direction. The long axis "a" is preferably from 14 to about 20 millimeters, while the short axis "b" is preferably from 13 to about 15 millimeters. Preferably, the long axis "a" is about 16 to 18 millimeters, while the short axis "b" is about 13. 5 to about 14.5 millimeters.

The radii of curvature of the toric lens depend on the characteristics of the patient's eye. The design of toric contact lenses is described more broadly in "Contact Lens Practice", Fourth Edition, Robert Mandell, pp. 659-680 (1988); "The Contact Lens Manual", A. Gasson and J. Morris, pp. 196-207 (1992); and "Clinical Contact Lens Practice," revised edition, E. Bennett and B. Weissman, pp. 1-12 (1993); each of which are incorporated here as a reference. The rotationally stabilized contact lenses of the present invention can be manufactured by means of various techniques, such as molding on both sides, conventional mechanical turning, or laser-ablative tornado techniques. Preferably, the rotationally stabilized oval contact lenses are manufactured from the molding techniques of 12 both sides, because the more complex oval shape is more suitable for some molding techniques. In a preferred concept, the present toric lens, rotationally stabilized, has a radius of curvature, ri # in a substantially spherical, inner portion and of visual correction, and a second radius of curvature, r0, in an outer portion of rotational stabilization , this is in an external area that has a border that defines the preferred oval shape. The different radii of curvature may be necessary for an adequate adjustment of the rotationally stabilized oval lens with the patient's eye. For example, in some cases, the internal radius of curvature, rt, will be too small, and will therefore cause the lens to exert excessive pressure on the eye. This excessive pressure can cause the lens to distort or mark the eye tissue, especially at the periphery of the lens. In other cases, the internal radius of curvature will be too large, such that if this internal radius extends evenly from the center of the lens to the edge, the lens will fit properly to the eye at its center, but will bend or separate from the center. eye on the edge of the lens. Therefore, in the preferred concept, shown in FIGS. 8 and 9, the rotationally stabilized, oval oval lens 50 has a first internal radius of curvature, r, in the inner vision correction portion 52. The portion Vision Corrector 52, which is typically substantially spherical, is located in the center and includes the toric surface 54. This preferred lens has a second outer radius of curvature, r0, which is different from the first internal radius, in the outer rotational stabilization area 56, extending from the periphery 58 of the inner portion of the correction of the view 52, to the peripheral edge of the lens 60. The peripheral edge of the lens 60 defines an oval shape 62 which provides the rotational stability of the lens 50. Figures 8 and 9 illustrate the overall edge of the lens, which preferably has a shape oval, with a major axis of length "a" and a minor axis of length "b", where a > b.

A preferred version of the internal area of vision correction can be defined as an area spherically extending from the center of the lens to the periphery. The diameter of the internal area of vision correction, from a plane view, can be about 11 to 15 mm. This diameter is shown as "D" in Figure 8. Preferably, the internal area of vision correction has a diameter of 12 to 14.5 mm.

The dimensions of the internal and external radius, which will produce an adequate fit for a particular patient, are clearly dependent on the characteristics of the patient's eye shape. However, in general, the radius of curvature of the inner area, r, can vary from about 7 mm to 10 mm, while the radius of curvature of the external area, r0, can 11 vary from about 8 to about 13 mm. Preferably, the internal radius is between 7.5 and 9.5 mm, and the external radius is between 9 and 11 mm. In a further concept, a multifocal lens is rotationally stabilized by providing the lens with a peripheral non-circular edge, as described above. As shown in figure 10, the bifocal lens 80 includes an inner vision correction portion 86 having a diameter of 11 to 15 mm and a radius of curvature of the base curve of 7 to 10 mm. The lens 80 further includes an outer rotational stabilization portion 88 extending from the inner vision correction portion 86 to the oval edge 90. Within the internal vision correction portion 86, there is a first and a second second region of vision correction, 82 and 84, respectively.

The first view of vision correction 82 preferably has a diameter of 7 to 9 mm in the plane view and a radius of curvature of the base curve of 7 to 9.5 mm. The second region of vision correction 84 preferably has a diameter of 2 to 4 mm in the plane view and a radius of curvature of the base curve that provides a power difference of 1 to 3.5 diopters, with respect to the first portion of vision correction 82. As discussed above, in order to avoid or minimize diplopia, bifocal lenses should be designed in such a way that the focal optic is aligned with the visual axis of the eye. According to this, the First and second regions of vision correction 82 and 84 are preferably displaced from the center of the lens, such that the centers of these vision correction regions correspond substantially to the center of the visual axis of the patient. To achieve this alignment, the centers of the vision correction regions 82 and 84 are preferably offset about 1 to 2 mm toward the nasal side (this means towards the right side for the lens of the left eye, or towards the left side for the lens of the right eye), with respect to the minor axis of the edge of the oval 94, and deviated from 0.5 to 2 mm above the major axis of the edge of the oval 92. However, the vertical deviation of the vision correction centers may be above or below the major axis of the oval edge 92, depending on the particular characteristics of the patient's eye.

The above discussion will allow someone who has ordinary skill in this technique to carry out the invention. In order to allow the reader to better understand the specific concepts and their advantages, it is recommended to refer to the following examples.

EXAMPLE 1 An oval contact lens was made, with a peripheral edge of the lens defining an oval having a long axis of about 14.5 millimeters and a short axis of about 13 mm. The lens was manufactured with a radius of 8.9 mm base curve curvature along the entire lens surface. The lens produced an unexpected and undesirably flat adjustment on the short axis, resulting in a "separation of the edge", a situation in which the edge of the lens does not remain in intimate contact with the eye. This result shows that proper adjustment may require providing the lens with a radius of curvature, ri t in an interior vision correction portion, and a second radius of curvature, r0in an external rotating stabilization portion.

EXAMPLE II An oval, rotationally stabilized lens was fabricated with a rear surface of the lens (base curve) being a truly toric surface. The toric surface has a radius of 8.74 mm along one axis of the cylinder and 9.42 mm along the other axis of the cylinder. An advantage of this design is that the production complexities can be reduced because the entire surface is toric, instead of just the central area. However, it is believed that the design is not advantageous, because both the cylinder power and the adjustment are changed when the toric spokes are changed. Therefore, in order to provide adequate vision correction for many patients, an additional toric surface may be required in the front curve of the lens, thereby increasing the complexities of production and cost.

EXAMPLE III An oval contact lens was made, with the edge of the periphery of the lens defining an oval having a long axis of 15.8 millimeters and a short axis of 13.8 millimeters. The lens was given a radius of curvature of 8.74 mm for the inner portion of vision correction (this means an equivalent radius with a diameter of 13.8 mm). The lens was also provided with a radius of 9.42 mm in the outer portion of rotational stabilization (this means a radius equivalent to a diameter of 15.8 mm) The equivalent radii of curvature for the vision correction portion and for the rotational stabilization portion were achieved by providing an actual radius of curvature of 8.45 mm from the center of the lens to a diameter of 11 mm (from the plane view); providing a true radius of curvature of 8.80 mm from the diameter of 11 mm to a diameter of 13.5 mm; and providing a real radius of curvature of 11 mm extending from a diameter of 13.5 mm to the edge of the lens. Both the short and long axis fit the eye properly, without producing a substantial ocular distortion or the "lifting on the edge" of the lens.

EXAMPLE IV An oval, rotationally stabilized contact lens was fabricated as described in Example III, with the addition of a toric surface in the base curve of the lens. The toric area imparts a difference of 1.00 diopter to the power of the cylinder, between the major and minor axis of the oval bank. In a plan view, the radii of the toric area are aligned with the major and minor axes of the oval edge, comprising about 9 mm along the major axis and about 8 mm along the minor axis.

EXAMPLE V A bifocal, oval contact lens is manufactured according to the description of the rotational stabilization characteristics of Example III. Using the rotational stabilization structure of Example III, a bifocal optical region is added to the base curve of the lens. A first region of vision correction of 8.0 mm in diameter imparts a power of -3.0 diopters. A second region of vision correction of 2.3 mm in diameter imparts an increase in power of 2.0 diopters with respect to the first region. The centers of the vision correction regions are offset 1.4 mm from the center of the lens to the nasal side of the minor axis of the edge of the oval lens and 1.0 mm above the major axis of the edge of the oval lens.

The invention has been described in detail, with reference to certain preferred concepts, in order to allow the

Claims (18)

reader who practices the invention without the need for extensive experimentation. However, a person who has an average knowledge of the technology will quickly recognize that many of the components and parameters can be varied or modified to a certain degree, without deviating from the approach and concept of the invention. Additionally, titles, headings, or others, are provided to enhance the reader's understanding of this document, and should not be read as limiting the scope of the present invention. Accordingly, the intellectual property rights of this invention are defined solely by the following claims and any reasonable extension thereof. NOVELTY OF THE INVENTION Having described the foregoing invention, it is considered as a novelty and therefore the content of the following claims is claimed as property: CLAIMS

1. A rotationally stabilized contact lens, having a non-circular shape of the peripheral edge, in which the periphery of the lens has a first dimension in a first cross section of the lens and a second dimension in a second cross section of the lens, wherein said first and second cross sections mentioned above, are located on planes that are substantially parallel to the direction of vision passage through the lens, wherein said first cross section is substantially perpendicular to said second cross section, and wherein said first dimension is larger than said second dimension, wherein said non-circular edge shape allows the lens to remain substantially rotationally stable when placed over the patient's eye, with said first section having a larger first dimension, mentioned above, remaining substantially horizontal when the lens is over the eye.

2. A rotationally stabilized contact lens according to claim 1, wherein said edge of the periphery of the lens has a substantially oval shape from a top view, having a long axis in said first section, and a short axis in said second section.

3. A rotationally stabilized contact lens according to claim 2, wherein said long axis is 14 to 20 millimeters, and wherein said short axis is 13 to 15 mm. ü

4. A rotationally stabilized contact lens according to claim 3, wherein said long axis is 16 to 18 millimeters, and said short axis is 13.5 to 14.5 millimeters.

5. A rotationally stabilized contact lens according to claim 1, wherein said lens is a toric lens.

6. A rotationally stabilized contact lens according to claim 1, further including an inner vision correction portion having a first radius of curvature and an outer rotational stabilizing portion having a second radius of curvature, wherein said outer stabilization portion of rotation extends from said inner portion of vision correction to the edge of said lens, and wherein said first radius differs from the second radius.

7. A rotationally stabilized lens according to claim 6, wherein said first radius is smaller than said second radius.

8. A rotationally stabilized lens according to claim 7, wherein said first radius is longer than said second radius.

9. A rotationally stabilized lens according to claim 7, wherein said first radius is 7 mm to 15 mm in said inner portion of vision, and said second radius is 8 to 13 mm in said outer stabilization portion. of rotation.

10. A rotationally stabilized lens according to claim 9, wherein said first radius is 7.5 to 9.5 mm, and said second radius is 9 to 11 mm.

11. A rotationally stabilized lens according to claim 4, further including; a toric surface, and an inner portion of vision correction having a first radius of curvature of between 7.5 and 9.5 mm, and an outer portion of rotational stabilization having a second radius of curvature of between 9 and 11 mm, in wherein said outer rotation stabilizing portion extends from said inner vision correction portion to the edge of said lens.

12. A rotationally stabilized lens according to claim 1, which is a multifocal lens, having a plurality of vision correction regions.

13. A rotationally stabilized lens according to claim 12, which is a bifocal lens, having a 23. first region of vision correction located substantially in the center, and a second portion of vision correction located within said first region of vision correction.

14. A rotationally stabilized contact lens according to claim 12, wherein the centers of said plurality of vision correction regions are substantially aligned with one another and offset from the center of said lens.

15. A rotationally stabilized contact lens according to claim 14, wherein the centers of said vision correction regions are located 1 to 2 mm horizontally from the center of said lens, when said lens is placed over the eye.

16. A rotationally stabilized contact lens according to claim 14, wherein the centers of said vision correction regions are located 1 to 2 mm vertically from the center of said lens, when said lens is placed over the eye.

17. A method for imparting rotational stability to a contact lens, including imparting to a lens, of a non-circular shape of the peripheral edge, seen from the plane, wherein the periphery of the lens has a first 21 dimension in a first cross section of the lens and a second dimension in a second cross section of the lens, wherein said first and second cross sections are in planes substantially parallel to the direction of the passage of vision through said lens, in wherein said first cross section is substantially perpendicular to said second cross section, and wherein said first dimension is longer than said second dimension, wherein said non-circular shape of the edge allows said lens to remain substantially rotationally stable when placed on the patient's eye, with said section having a first longer dimension that remains substantially horizontal when the lens is over the eye.

18. A method for providing a non-circular lens with a suitable fit to the patient's eye, said lens having an internal portion designed to correct the patient's vision and an external portion designed to rotationally stabilize the lens on the eye, said method includes the steps of : (a) providing said inner portion of vision correction with a first selected radius to be adjusted UP. suitably to the portion of the eye that is intended to be adjacent to said inner portion of vision correction; Y (b) providing said outer portion of rotational stability with a second radius, suitably selected to conform to the portion of the eye which is intended to be adjacent to said external portion of rotational stability. il ROTATIONALALLY STABILIZED CONTACT LENSES AND LENS STABILIZATION METHODS Contact lenses, especially toric and bifocal, which are substantially rotationally stabilized and methods to stabilize contact lenses. Contact lenses are stabilized with respect to rotation when placed on the eye, by providing the lens with a non-circular shape. In a preferred concept, a toric lens is rotationally stabilized by providing the lens with an oval shape. Methods for providing noncircular lenses having suitable shapes to correctly fit the patient's eye are also presented.