JP2003514597A - Multifocal aspheric contact lens - Google Patents

Abstract

  (57) [Summary] Provided is an optical surface for correcting presbyopia, which is brought into proximity with a human pupil, a method for obtaining the optical surface, and a laser surgical system for performing the method. The optical surface includes a first viewing zone, a second viewing zone surrounding the first viewing zone, and a third viewing zone surrounding the second viewing zone, wherein the first viewing zone is a first viewing zone. The second viewing zone has a range of refractive power and the third viewing zone has a second substantially different power than the first single refractive power. The first, second and third viewing zones have an aspheric surface and the other zones have a spherical surface. The method includes reshaping the cornea to obtain this optical surface. The cornea can reform the anterior or underlying surface by erosion or collagen shrinkage, which is performed by applying excimer laser, surgical laser, water cutting, fluid cutting, liquid cutting or gas cutting techniques. I do. The method also includes obtaining the optical surface by placing a contact lens having desired optical properties on the cornea. The laser surgery system adjusts the beam striking the cornea with a laser beam generator to remove a selected amount of corneal tissue from the area of the optical zone of the cornea with erosive radiation, thereby providing a first viewing zone, A laser beam control for forming a re-profiled region having a second viewing zone surrounding the first zone and a third viewing zone surrounding the second viewing zone.

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION Simultaneous vision refers to a type of bifocal contact lens in which the optical power for distance vision and the optical power for near vision are simultaneously located within the pupil area of the user.
Conventional clinical knowledge for simultaneous vision is that a bifocal lens projects distant and near images simultaneously onto the retina. Depending on the viewing distance of the object, one of the images is in focus and the other is out of focus. It is believed that the brain can ignore irrelevant defocused images and process only relevant in-focus images. Thus, the lens can provide an acceptable level of visual acuity for many patients regardless of whether the object is in a distant or near position.

There have been attempts in the past to provide simultaneous vision contact lenses. One type of simultaneous vision lens is a concentric zone bifocal lens in which the distance power and the near power form two concentric optical zones. These lenses included a far-center or near-center structure. The dimensions of the two zones are selected to provide approximately equal areas of distance and near power within the pupil area. This lens includes the advantage of providing the user with two relatively large optical areas on the lens. However, the size of the user's pupils varies from user to user and depending on the ambient light level, so the relative area between the distance and near powers deviates significantly, resulting in near vision. Or, one of the distance vision comes to be prioritized at the expense of the other. This distant or near-field bias may not be appropriate for a particular user's visual acuity requirements, as this dependence on pupil size is not controllable by the user.

To reduce this dependence on pupil size, additional concentric zones can also be incorporated into the lens. See, for example, US Pat. No. 4,704,016 (Cohen). The full bifocal optical zone of such a lens consists of a series of concentric annuluses which must be located in the pupillary zone, which alternately provide distance and near power.
However, as the number of annuluses increases, the width of each annulus must be reduced if the zones (or at least a significant portion thereof) must remain in the pupillary zone.
This reduces the optical properties of the distance power and the near power due to the size reduction of each zone. In addition, the boundaries between the various zones cause unwanted edge effects. This optical degradation can offset the potential benefit of reducing the dependence on pupil size by incorporating multiple zones.

Another type of simultaneous vision lens involves the use of an aspheric surface within the bifocal optical zone that continuously grades the optical power over a range of selected powers. The gradient power gradient must be designed to provide the desired difference between the near and far power values (ie, the desired bifocal additive power) in the pupil area. . Therefore, the visual performance of the aspherical simultaneous lens design is similar to that of the concentric zone design.
Limited by a similar dependence on pupil size. Moreover, by attempting to provide all power corrections over the full range of values between distance and near, aspheric designs provide the visual quality provided at a particular power value. Impair.

An example of an aspherical lens is US Pat. No. 5,754,270 (Rehse et al.).
The '270 patent discloses a centrally located first aspherical optical zone, a concentric second aspherical optical zone, and a rapid refractive power shift between the first and second zones. And a transition zone to provide a lens. This lens is
Since it includes a range of powers rather than a selected power zone, it suffers from the drawback of impairing the visual acuity of the user at a particular power value.

Yet another type of simultaneous vision lens is based on diffractive optics. In theory, this lens provides approximately equal levels of distance and near vision with minimal dependence on pupil size, but in practice, the clinical acceptance of diffractive bifocal contact lenses is relatively low. It is not clear whether this low acceptance is mainly due to the quality limitations inherent in diffractive optics or the complexity of diffractive optics which is very difficult to manufacture.

In order to develop higher performance designs, it must first be recognized that the above conventional description of simultaneous viewing can be erroneous. The conventional theory is that the brain somehow distinguishes by describing simultaneous vision in terms of near and distant images,
It is assumed that there are two separate retinal images that can be processed separately. At any particular moment, the eye is looking at a particular object at a particular viewing distance. With all simultaneous vision lenses, a partially degraded image of the object is projected onto the retina. The result of this image degradation is the loss of visual information (decreasing signal, increasing noise), and the degraded image quality may not be acceptable to the patient. The clinical effect of this deterioration is
It can be objectively measured by converting it into a decrease in visual acuity and contrast sensitivity. The subjective effects of deterioration are perceived by the patient in a variety of ways collectively referred to as "conscious blur." Thus, when wearing a simultaneous vision lens, the patient may not choose between separate distant and near images. Rather, in the presence of subjective blur, the patient may seek to function with a reduced level of visual information provided by the degraded image.

The visual system does not have the ability to filter out some of the noise, and many patients present an enormous potential to adapt to subjective blur. For some patients, adaptation is complete,
It may not report any subjective blur, despite the apparent loss of vision by objective measurements. However, while the objective assessment shows normal visual performance, the opposite situation may occur in which the patient paradoxically complains of visual impairment.

Therefore, there is a need for an improved simultaneous vision lens design that maximizes the visual information available to objects at distant and near positions while minimizing visual disruption. is there. There is also a need to apply the improved design to alternatives to contact lenses, such as the latest corneal reshaping techniques under development that are becoming more common alternatives.

SUMMARY OF THE INVENTION The present invention provides an optimum that allows for improved visual acuity over a range of distances, yet reduces visual confusion resulting from transitions between areas such as those formed by lenses in the past. To provide an optimized lens structure. There is also a need for a lens that combines the positive features of the concentric design with the positive features of the aspherical design to create a unique integrated design that minimizes each drawback.

Briefly stated, the present invention provides a lens having multiple viewing zones. The plurality of areas includes a first viewing area, a second viewing area that surrounds the first viewing area, and a third viewing area that surrounds the second viewing area. The first viewing zone has a first power, the second viewing zone has a range of powers, and the third viewing zone has a second power that is different from the first power. Have. One of the first, second and third viewing zones has an aspheric surface designed to provide a monotonic gradient of power, the other zone provides a single power value. Spheres or aspherical surfaces designed to correct optical aberrations in these single power zones.

Accordingly, one embodiment of the present invention reprofiles the cornea to
A method of providing the eye with multifocal ability for correcting presbyopia. The method comprises providing a laser operable to deliver ablative laser radiation to the cornea, and selectively exposing the cornea to the ablative radiation to provide a first viewing area, a first area. A second viewing area surrounding the second viewing area and a third viewing area surrounding the second viewing area,
The first viewing zone has a substantially single power, the second viewing zone has a range of powers, and the third viewing zone differs from the first single power. A second, substantially single refracting power, at least one of the first, second and third viewing zones having an aspherical surface and two other zones having a spherical surface; Creating second and third viewing zones.

In a second embodiment, the invention relates to a method of changing the curvature of the cornea for the correction of presbyopia. In this method, a thin layer-shaped incision extending like an incomplete circle is made on the surface of the cornea to form a surface layer connected to the cornea at a portion near the parietal surface, and the surface layer is turned up to form the lower surface of the cornea. Is exposed and ablation or removal of tissue is performed on the underlying surface to change the curvature of the cornea to alter the first viewing zone, the second viewing zone surrounding the first zone and the first viewing zone. A third viewing zone surrounding the second viewing zone, the first viewing zone having a substantially single refractive power, the second viewing zone having a range of refractive powers, The third viewing zone has a second substantially single refractive power different from the first single refractive power, and at least one of the first, second and third viewing zones has an aspheric surface. And creating first, second and third viewing zones, where the other zones have spherical surfaces, and returning the surface to the top of the underlying surface.

In a third embodiment, the invention relates to an optical surface for correcting presbyopia, which is close to the pupil. The optical surface includes a first viewing area, a second viewing area that surrounds the first area, and a third viewing area that surrounds the second viewing area, where the first viewing area is the first substance. Has a single refractive power, the second viewing zone has a range of refractive powers, and the third viewing zone has a second substantially different refractive power from the first single refractive power. It has a single refractive power and at least one of the first, second and third viewing zones has an aspherical surface and the other zone has a spherical surface. Preferably, the point on the optical surface is obtained by the following equation.

[0015]

[Equation 7]

Where Z ₁ is the chord diameter of the central first viewing zone, Z ₂ is the chord diameter (outer diameter) of the second viewing zone, and Z ₃ is the third viewing zone. The chord diameter of the zone, Z ₁ is 1.2 mm
2.1 mm, Z ₂ is 2.0 mm to 4.8 mm, Z ₃ is less than 8 mm,
The specific values assigned to the variables r _i , p _i , ε _i , η _i and Z _i (i = 1, 2 and 3) are selected to provide the patient with the desired refractive index and presbyopia correction. More preferably, p ₁ = p ₃ = 1 and η ₁ = η ₃ = 0, and for i = 2, η ₂ = 0 is arranged by appropriate choice of other variables.

In a fourth embodiment, the invention relates to a method of reshaping the cornea to obtain the optical surface of the third embodiment. The method involves reforming the anterior or underlying surface of the cornea by ablation or collagen contraction, which employs excimer laser, surgical laser, water cutting, fluid cutting, liquid cutting or gas cutting techniques. It is carried out by
Corneal reshaping also involves placing a contact lens with the desired optical properties on the cornea, or embedding a lens with the desired optical properties into the cornea to place the optical surface on an artificially created anterior surface of the cornea. Can also include obtaining.

In a fifth embodiment, the invention relates to a method of pre-adapting a patient to final presbyopia correction prior to corneal reshaping. The method comprises a first viewing zone in the central area of the pupil, a second viewing zone surrounding the first area and a third viewing zone surrounding the second viewing zone, the first viewing zone The area has a first substantially single power for near vision correction, the second viewing area has a range of powers, and the third viewing area has a first single power. A second substantially single power different from the power, the second power is for distance vision correction, the first and third viewing zones have spherical surfaces, and the second Providing the patient with a pair of multifocal contact lenses, each of which includes a first, second and third viewing zone, the areas of which have aspheric surfaces. After the lens has been worn for a short period of time to accommodate the vision correction by the multifocal lens, the cornea is reformed to provide the patient with satisfactory vision correction. Achieve an optical surface that provides a profile. The method is also preferably independent of the dominant and non-dominant eyes, step by step as necessary to achieve presbyopia correction that is satisfactory to the patient at near, far and intermediate distances. Different first refractive power,
By providing a patient-replacement multifocal contact lens having a different second power, a different Z ₁ or Z ₂ size or a combination of different first and second powers and zone sizes, the desired presbyopia correction is achieved. Can be improved.

As used herein, “lens” is broadly interpreted to include a variety of lenses including contact lenses and intraocular lenses.

As used herein, “refractive power” is also broadly construed to include a single power or an average power.

Further, as used herein, “a range of refractive power” is broadly construed to include a substantially continuous or discontinuous series of refractive powers.

As used herein, “area” is broadly construed to include zones or areas.

[0023]   As used herein, the "visual area" includes an area that contributes to the vision of the user.

The present invention, together with attendant objects and advantages, will be clearly understood by reference to the following detailed description in connection with the accompanying drawings.

Drawings and Detailed Description of the Preferred Embodiments FIG. 1 is a front view of the optical portion of one preferred embodiment of the present invention, also represented in part by the graph shown in FIG. FIG. 1 shows a contact lens 10 having a near-center structure. Central zone 12 is a single power zone that provides the desired near power. Outer zone 16 is a single power zone that provides the desired distance power. The intermediate zone 14 is a gradient power aspheric zone that provides a continuous monotonic power change from the near power of zone 12 to the far power of zone 16. It should be appreciated that when the central area 12 and the outlying areas 16 are single power areas in the preferred embodiment, each of these areas may also be formed from a plurality of areas having multiple powers. Is. The dotted circles in area 16 represent typical pupil size dimensions.

The intermediate zone 14 acts as a zone of long depth of focus. As such, the intermediate zone 14 contributes to visual acuity over a range of objective distances, including those for distance vision, near vision and intermediate vision. When the object is in a close position, the central area 12 and the intermediate area 14 combine (about 70% of the 3.0 mm pupil area or about 52% of the 3.5 mm pupil area in one of the examples below). Contribute to myopia. When the object is at a distant position, the intermediate area 14 and the outlying area 16 combine (about 61% of the 3.0 mm pupil area or about 72% of the 3.5 mm pupil area in one of the following examples). ) Contribute to distance vision. At the intermediate distance, the intermediate area 14 is approximately 32% of the 3.0 mm pupil area.
Or provide a useful level of intermediate distance vision over approximately 24% of the 3.5 mm pupil area.

The dimensions of the three zones must be calculated appropriately to maximize the utilization of the pupil area for distance and near vision, and various factors such as required power, pupil size, It depends on ocular aberrations and other patient and application related factors. Thus, if desired, each lens may be ordered to suit the user's specified power prescription and other personal characteristics. In addition to the user's distance and near power prescriptions, factors such as pupil size, occupational requirements, and personal habits and preferences are also taken into account to create a custom designed lens, i.e., for a particular user. Lenses can be manufactured with optical areas, power values and dimensions that are specifically selected to meet the needs. Alternatively, the dimensions of the three zones may be standardized to a number of choices that meet the needs of most of the average user population and are also economies of scale derived from mass production. A toric surface may be used with the lens to correct astigmatism. The toric surface will be used on the side facing the areas 12, 14, 16.

In one embodiment, the diameter and pupil area% values for each zone for a typical pupil size are listed below.

[0029]

[Table 1]

In the most preferred embodiment, the% values of the diameter and pupil area of each zone for a typical pupil size are listed below.

[0031]

[Table 2]

Preferred embodiments are shown in Tables 1-2, with the central zone 12 being in the range 1.0-3.8 mm, more preferably 1.2 mm-2.1 mm, most preferably 1.5 mm.
It can have a range of up to 1.9 mm. The intermediate section 14 can have a minimum diameter of 1.2 mm and a maximum diameter of 4.8 mm, more preferably an inner diameter in the range of 1.2 mm to 2.1 mm and an outer diameter of 2.3 mm to 3.0 mm. Outer area 16 is 2.0 mm
And a maximum diameter of 10.0 mm, more preferably an inner diameter of 2.3 mm to 3.0 mm and an outer diameter of 4.0 mm to 9.0 mm.

The lens is easy to design to have a desired value for the bifocal additive power. In normal clinical practice, the most commonly prescribed additive power is +0
． Although it is in the range of 75D to + 2.50D, an additive refractive power exceeding this range may be prescribed. Then, the radius of curvature of the central area 12 and the outer area 16 is determined from the prescribed distance optical power, and the additive optical power is determined from the standard optical method commonly used by those skilled in the art. Then, the method described in detail below is used to determine the variables that specify the aspherical area of the present invention. The table below shows the details obtained in the sample range of distance power in a lens of +1.50 D additive power with the zone dimensions described above in Tables 1-2. In the table, r ₁ , r ₂ and r ₃ are variables indicating the radii of curvature of the central area, the intermediate area and the outer area, p ₂ is a variable indicating the asphericity of the intermediate area, and ε ₂ and ε ₃ is a position variable of the middle area and the outer area. All these variables will be explained more fully below, as we develop the mathematical description in the formulas for each of these aspects. In these examples, it is assumed that multiple optical zones are at the anterior surface of the contact lens, but each example may be calculated for its equivalent posterior surface arrangement if desired.

[0034]   Rear radius: 8.30mm   Center thickness: 0.08mm   Refractive index: 1.412   Bifocal addition refractive power: + 1.50D

[0035]

[Table 3]

[0036]

[Table 4]

The transition between the central zone 12 and the intermediate zone 14 and the transition between the intermediate zone 14 and the outlying zone 16 have a significant impact on the vision, an improvement over the prior art. Figure 2
1 shows the cross-sectional appearance of a prior art concentric two-section bifocal lens (curves exaggerated to make the surface profile features visible in the figure). At the intersection of the two concentric zones (point A in Figure 2), a sharp angle is created in the surface profile, at which sharp local tangent to the surface profile becomes discontinuous. Therefore,
The local tangent to the surface profile approaches different limits as one approaches the intersection from both sides of the corner. The presence of sharp corners causes undesired edge effects due to diffraction and due to prism differences induced between off-axis rays incident on each side of the corner. In spectacle bifocal lenses, this induced prismatic difference is known as "bifocal jump," and most spectacle bifocal lenses are specifically designed to mitigate this confusing visual effect. There is.

The sharp corners in FIG. 2A can be rounded by a blend curve connecting the two areas (dotted curve B in FIG. 2). Such blend curves can eliminate local tangent discontinuities to the surface profile and can be created, for example, by polishing or buffing the original unblended surface. However, simply rounding a sharp corner cannot completely eliminate the corner or its effect. As shown in FIG. 2, the surface profile of the area of the original concentric zone is downwardly concave in the figure, while the area of the blend curve B is upwardly concave in the figure. There is no tangent discontinuity, but the slope sometimes increases in value and sometimes decreases.
This means that the second derivative for the surface profile changes sign on each side of the rounded corner. The potential for confusing edge effects still exists with such blended profiles. The transition of the present invention significantly avoids these disruptive effects.

FIG. 3 partially shows the embodiment of FIG. 1 in cross section. In Figure 3,
The surface profile of the intermediate aspherical area 14 is represented by a dotted line so that it can be distinguished from the central area 12 and the outlying area 16 shown by the solid line. There is no visible physical separation at the boundary between the intermediate zone 14 and the central zone 12 or the outboard zone 16 of the preferred embodiment. Therefore, the profile is smooth and continuous, has no sharp or rounded corners, and is always downwardly concave with respect to the particular structure. Central area 1
Since the intermediate area 14 between the 2 and the outlying area 16 is completely unbroken, there are no sharp boundaries that would cause undesired edge perturbations, such as the bifocal jump effect.

Each surface area or zone of the present invention is a surface of revolution. As such, the surface of each zone can have its cross section mathematically specified in two dimensions. Then, by rotating the cross section around the rotation axis, a complete three-dimensional surface is generated. In the simplest form of the invention, this axis of rotation is also the optical axis of the contact lens, on which the geometric center of the contact lens lies. However, in order to achieve a more favorable placement of the optical system with respect to the eye, it may be appropriate to shift the optical area of the contact lens from the contact lens geometric center. For example, if the average position of the contact lens is not centered with respect to the eye, then it may be preferable to decenter the optical section so that the optical section is centered with respect to the eye rather than with respect to the contact lens. is there. Furthermore, it is known that the eye itself is not a center-aligned system. For example, the pupil is usually not centered with respect to the visible iris and the visual axis of the eye is usually not centered with respect to the pupil. By offsetting the center of the contact lens optics so that the final position of the optical zone is centered with respect to the pupil or the visual axis of the eye, all these alignment deviations can be corrected. In order to maintain this desired alignment of the optical area to the eye, contact lenses must also incorporate appropriate systems to stabilize the lens, as commonly found in toric surface contact lenses. For example, a prism ballast system may be used to maintain the correct orientation of the contact lens with respect to the eye. However, if the geometric center of the lens lies on the optical axis, such a stabilizing system is not necessary.

The cross-sectional profile of the rotating aspheric surface can be conveniently described in terms of a conical cross section. If the cross section of the surface of revolution is not a true conical cross section, then a small area of the surface profile can be approximated by a part of the conical cross section.

One form of the formula for the conical section is shown in formula (1). Where r is the radius of curvature at the apex of the surface (apex radius), y is the distance from the axis of the conical section to a point on the surface, and x is the axial distance from the apex to the surface point. Is. In contact lens technology, the distance x is commonly referred to as the sagittal distance or sagittal depth, and 2y is the chord diameter (y is the half chord diameter) with respect to the sagittal distance x. Equation (1) is convenient because it can be used to describe both spherical and aspherical surfaces.

[0043]

[Equation 8]

The variable p is a quantity indicative of the asphericity of the surface and is related to the well-known eccentricity e of the conical cross section by equation (2) or equation (3). If the curvature of the surface becomes flatter as the point on the surface moves away from the vertex position, then equation (2) applies and if the curvature of the surface becomes steeper as the point moves away from the vertex position, then equation (3) ) Applies. It is also appropriate to use the relevant variable k = p-1 in equation (4) as the asphericity variable.

[0045]   The following table summarizes the relationship between these asphericity variables and common surfaces of revolution.

[0046]

[Table 5]

Thus, with proper choice of the asphericity variable p, equation (2) can be used to indicate both spherical and aspherical surfaces.

Since the present invention provides a contact lens having multiple zones, equation (1) can be refined as in equation (5). In the formula (5), the index i is used to represent the formula showing the i-th surface area. For example, i = 1 indicates the first surface area, i = 2 indicates the second surface area, and so on.

[0049]

[Equation 9]

Equation (5) shows the surface where the vertex of the surface is located at the origin of the coordinate system. Considering the fact that not all vertices of different surfaces are at the origin, equation (5) must be further generalized as in equation (6). In equation (6), ε _i and η _i are
Are the x and y coordinates of the surface vertices, respectively

[0051]

[Equation 10]

The inverse relationship of equation (6) is shown in equation (7). This formula provides a convenient formula for the sagittal depth of the surface as a function of the (half) chord diameter.

[0053]

[Equation 11]

The surfaces of the present invention are not limited to surfaces derived from a conical cross section. Equation (7) can be further generalized to include higher order terms, as in equation (8), to accommodate aspheric surfaces deviating from the conical cross section. The inclusion of such higher order terms may be desirable to minimize or eliminate certain optical aberrations.

[0055]

[Equation 12]

For the sake of brevity in mathematical development, these higher order terms are not included in the description that follows, but may be incorporated into alternative aspects of the invention if desired. Therefore, the following expansion uses equation (7) rather than equation (8).

In a preferred embodiment of the invention, the anterior surface of the contact lens comprises three zones within the multifocal optical zone. Each zone has its own characteristics and requirements,
The point on the optical surface containing the three zones can be simply shown by the following equation derived from equation (6) above.

[0058]

[Equation 13]

In these equations, Z ₁ is the chord diameter of the central first zone, Z ₂ is the chord diameter (outer diameter) of the second zone, and Z ₃ is the chord diameter of the third zone. Is. Therefore,
Once specific values are assigned to the variables r _i , p _i , ε _i , η _i and Z _i (i = 1, 2 and 3), the surface profile of the three zones is completely defined by the above equation. .

The unique features of the present invention can now be described in terms of its physical and mathematical requirements. These requirements are then used to derive the values of the variables r _i , p _i , ε _i , η _i and Z _i that specify the preferred embodiment of the present invention.

The starting point for designating the preferred embodiment is the choice of zone dimensions Z ₁ , Z ₂ and Z ₃ . The maximum zone Z ₃ is similar to the optical zone size of a conventional single vision lens. As such, it is designed to be significantly larger than the average pupil diameter. For example, typical values of Z ₃ is 8.0 mm. In dimensions,
There is a large tolerance, but usually it is probably 6.0 mm or above 6.5 mm. Also,
The theoretical upper limit for Z ₃ is the total diameter of the lens, but Z ₃ is usually smaller than the lens diameter to prevent the center or peripheral area of the lens from becoming too thick or too thin. Therefore, in a preferred embodiment, Z ₃ is set to 8.0 mm for many low to medium range powers, but higher + range or higher −.
Larger or smaller Z ₃ values are acceptable or desirable for a range of powers.

In a preferred embodiment, the central zone 10 is a single power zone designed to provide the power required for near vision. For prior art lenses where the central zone includes near power, the dimension of Z ₁ is for an average pupil diameter of 3.0 mm to 3.2 mm,
The area of the central near zone is selected to be substantially equal to 50% of the pupil area. For example, a central zone where Z ₁ equals 2.1 mm provides a central zone that is approximately 50% of the area of a 3.0 mm pupil. The rationale for this choice is that the simultaneous presence of the distance and near power zones in the pupil implies some compromise for the user, and that the distance and near vision requirements Is that each power zone must be substantially equal to 50% of the pupil area.

However, this rationale is not based on an analysis of the complete visual need of the average presbyope. The improved multifocal lens would not only provide better distance and near vision properties, but also vision for intermediate viewing distances. Accordingly, it is an object of the present invention to provide at least three optical zone areas for providing distance power, near power and progressive power for intermediate distance vision. The natural geometric result of incorporating such a third zone with progressive power, which occupies a substantial portion of the pupil area, is that the central near power zone is substantially less than 50% of the pupil area. It must be limited in size so that it only occupies.

In addition to the geometrical implications of incorporating at least three optical zone areas within the pupil area, another object of the present invention is that the visual needs of the average user are very broad. It is to provide the optimal placement of the zone areas that will be satisfied over the course of regular daily activities. For this reason, the size of the central near zone must be large enough to allow comfortable reading vision. However, if the central near zone is too large, near vision can be improved, but at the cost of diminishing the quality of distance and intermediate vision to the extent that it may be unacceptably impaired.
Therefore, it has been found that in order to achieve the full range of power requirements, the visual needs of the user are best met when the area of the central near zone is substantially less than 50%.

In a preferred embodiment, a dimension of Z ₁ = 1.86 mm enables a central near zone 12 that is about 38% of a 3.00 mm pupil diameter. For larger pupil diameters, this same central near zone 12 corresponds to a smaller portion of the pupil area. For example,
Z ₁ = 1.86 mm, which corresponds to approximately 38% of the area of a 3.00 mm pupil
The 2 dimension would only correspond to about 28% of the area of a 3.50 mm pupil.

The second annular zone 14 is the zone of gradient power and provides intermediate distance vision. Its outboard dimension Z ₂ is such that it provides a useful gradient power optical zone within the pupil while preserving the distance visual acuity provided by the outermost third optical zone or zone. Must be selected.

The variables r _i , p _i , ε _i and η _i of the first and third zones are the single power zones designed so that they provide the required optical power for distance and near vision. Therefore, it is relatively easy to specify. In a preferred embodiment, these monorefractive power zones may be spherical or aspherical to correct for optical aberrations such as contact lenses or spherical aberrations of the eye. The associated spherical aberration of the single power zone is relatively small because the dimensions of the zone are chosen to fit within the pupil. For example, 3
． For pupil sizes less than 6 mm, the spherical aberration in the corresponding area of the contact lens is substantially less than about 0.25D for most refractive powers. Therefore, the aspherical adjustment required to correct this level of aberration is also small. The spherical aberration of the eye varies from individual to individual, but is usually about 0.50 when the pupil size is less than 3.6 mm.
It is D or less. This requires somewhat larger aspheric adjustments, but is still relatively small compared to the adjustments required for the multifocal power of contact lenses.

For simplicity, in the mathematical expansion below, it is assumed that the single power zone is a sphere, ie its asphericity value is simply denoted by p ₁ = p ₃ = 1. Moreover, the spherical radii of curvature r ₁ and r ₃ of these zones are determined by the distance and near power prescriptions of the lens. Furthermore, the centers of curvature of these two spherical zones define the optical axis of the lens. And, by definition, the vertices of these spherical zones must lie on the optical axis. Therefore, η ₁ = η ₃ = 0.

The vertex positions of the first and third surfaces along the optical axis are specified by ε ₁ and ε ₃ , respectively. By convention, the origin of the coordinate system can be placed at the apex of the surface of the central zone without loss of generality (ε ₁ = 0). Then, the vertex position of the third surface is determined only by the value of ε ₃ . The vertex position ε ₃ also determines γ ₁₃ , which is the distance between the center of the first surface curvature and the center of the third surface curvature, which is obtained by the equation (12).

[0070]

[Equation 14]

In the absence of the second toroidal zone, the first and third spheres with a center-to-center distance γ ₁₃ intersect at a virtual zone boundary of diameter Z ₁₃ given by equation (13).

[0072]

[Equation 15]

Ε ₃ , and thus γ ₁₃ , must be selected so that Z ₁₃ satisfies the following equation (14). The virtual intersection boundary of the first surface and the third surface must be located within (and replaced by) the surface of the second zone. Otherwise, the first surface and the third surface would intersect at a boundary outside the second zone, unintentionally creating additional zones.

[0074]

[Equation 16]

First, equation (14) may appear to allow a degree of latitude in the choice of ε ₃ , such that the corresponding degree of latitude is obtained at the value of γ ₁₃ . However, the second zone 14
It will be understood below that the desired properties of the gradient power within s impose a further important constraint on ε ₃ that is not described in prior art multifocal contact lenses.

Then it remains to develop the values of r ₂ , p ₂ , ε ₂ and η ₂ that complete the designation of the aspherical surface of the second zone. An essential feature of the present invention is that the tangent to the lens surface is continuous at all points, especially at the boundaries of different areas or zones. The tangent to the surface profile of the ith zone is the first derivative y ′.
As very conveniently described. This is calculated from the equation (6) and the following equation (
15) is given.

[0077]

[Equation 17]

Expression (16) can also be obtained by combining Expression (15) with the inverse relationship shown in Expression (7). This formula provides a formula for calculating the tangent directly from the chord diameter,
This is convenient because it does not require explicit knowledge of sagittal depth.

[0079]

[Equation 18]

We now apply the requirement of continuity of y and y ′ to solve the variables r ₂ , p ₂ , ε ₂ and η ₂ which specify the aspherical surface of the second zone. For convenience, the quantities x ₁ , y ₁ , y ₁ ′ and x ₃ ,
y ₃ and y ₃ ′ are defined below. The half chord diameter at the boundary between the first zone and the second zone is calculated by the equation (17). Then, x ₁ , y ₁ , and y ₁ ′ are defined by the equations (18) to (20).

[0081]

[Formula 19]

Similarly, the half chord diameter at the boundary between the second zone and the third zone is obtained by the equation (21), and x ₃ , y ₃ , y ₃ ′ are defined by the equations (22) to (24).

[0083]

[Equation 20]

With respect to the quantities x ₁ , y ₁ , y ₁ ′, x ₃ , y ₃ and y ₃ ′, the continuity feature of the present invention can be summarized as four conditions or expressions. From equation (6), equations (25) and (26) are obtained, and from equation (16), equations (27) and (28) are obtained.

[0085]

[Equation 21]

These equations (25) to (28) represent a system of four nonlinear equations in four unknowns r ₂ , p ₂ , ε ₂ and η ₂ . Since the system of this equation is non-linear, it is convenient to go back and recalculate equation (6) for the second surface into the general quadratic equation of equation (29).

[0087]

[Equation 22]

Equation (29) can be slightly simplified by eliminating the cross product term Cxy. In the general case, this can always be achieved by a suitable rotation of the coordinate system, but due to the symmetry of the plane of rotation of the invention, a suitable coordinate rotation has already been carried out, so that C = 0. You can also assume. For example, an alternative, but equivalent, equation for the second surface is given by equation (30) and the corresponding relationship for the tangent is given by equation (31).

[0089]

[Equation 23]

Then, four equations equal to the continuity requirements of equations (25)-(28) are given by:

[0091]

[Equation 24]

Equations (32)-(35) are a system of four equations for the four unknowns A, B, D and E. However, a major advantage of this formula over equations (25)-(28) is that it is now a linear system of four unknowns and is easy to solve by standard methods. Is. In particular, the solution of this system can be written directly by using the Kramel's law method and the appropriate 4 × 4 determinant. For example, the determinant defined by the following expression (36) is designated as Q.

[0093]

[Equation 25]

Therefore, the four unknowns A, B, D, and E are obtained by the equations (37) to (40) by applying the Kramer's rule (if the determinant Q is not zero).

[0095]

[Equation 26]

Expanding the terms of equation (6) and comparing each coefficient of x, x ² , y and y ² with the corresponding coefficient of equation (30), finally r ₂ , p ₂ , ε ₂ and The desired relationship for η ₂ is obtained.

[0097]

[Equation 27]

It is assumed that the vertex position of the third zone given by ε ₃ only satisfies the general requirement of Z ₁₃ given by equation (14). However, it is an object of the invention that the aspheric second zone provides a useful optical zone in which the gradient power varies monotonically in only one direction. Such a refractive power profile is shown in FIG. FIG. 4 shows the optical power as a function of the chord diameter 2y for the example of the preferred embodiment of the invention. The optical power in the central first zone is essentially constant at near power values. In the peripheral third zone, the power is essentially constant at distance power values. In the second zone, the refractive power changes continuously and monotonically from the near value to the far value. A sufficient condition for producing this desired form of power profile in the second zone is η ₂ = 0. Therefore, η ₂ = 0 is a requirement of the preferred embodiment of the present invention.

From the equation (44), when E = 0, η ₂ = 0. By expanding the determinant of Expression (40), if the relationship shown in Expression (45) below is satisfied, η ₂ =
It can be shown that E = 0.

[0100]

[Equation 28]

In fact, equation (45) is the desired constraint on ε ₂ . Expression (46) is changed to expression (4
This is an identity that can be rearranged into the form shown in 7). Then, using the equations (45) and (7), the term of the equation (47) can be represented by a numerical value. The result is that for the third surface, η ₂ = 0 holds in relation to the continuity requirement, and that the power profile of the second zone of the aspheric surface has the desired monotonic progression shown in FIG. Is a condition for ε ₂ (regardless of whether ε ₁ = 0 is assumed).

[0102]

[Equation 29]

It has been found that a surprisingly slight (about half a micron) deviation of the surface from the preferred embodiment can cause undesired optical effects. Such small physical deviations from the preferred embodiment can cause significant optical effects, such as unwanted spikes or drops in the power profile, so that the required surface profile is faithfully produced. , The manufacturing process must be highly controlled. In prior art lenses that create an aspheric surface by a polishing or blending process, the process is not well controlled to allow an analytical description of the resulting surface profile. This low level of control cannot ensure that the specified requirements of producing the desired power profile shown in FIG. 4 are met, so that the power profile obtained by polishing or blending is not desirable as shown in FIGS. It is much more likely to have an effect.

Contact lens 10 complies with the following conditions resulting in a lens having the advantages of both spherical and aspherical lenses.

1. Looking at the surface profile of the contact lens 10 in cross-section (FIG. 3), the intersections of the intermediate section 14 with the central section 12 and the outer section 16 are smooth, continuous and without sharp corners. As any point in the surface profile approaches the intersection from each side, the tangent to the curve at that point approaches the exact same value at the actual intersection. Mathematically, the requirement is that the first derivative of the cross-sectional profile (dy / dx or y ')
Is continuous, especially that the first derivative is continuous at the intersections between the zones.

In the Cartesian coordinate system and the numbering system used above, this continuity requirement for the first derivative y ′ is summarized at the boundary between the central zone 12 and the intermediate zone 14 as be able to.

[0107] As made from the bottom to the y → Z _1/2, as it goes y → Z _1/2 from the top lim y '= y _1', in _{lim y '= y 1' y} = Z 1/2, y ′ ＝ y ₁ ′

That is, the first derivative y ′ has one unique value y ₁ ′ at the boundary between the central zone 12 and the intermediate zone 14, where y is Z ₁ / from each side of the boundary between zones. As you approach 2,
It approaches this one value y ₁ ′.

Similarly, the first derivative y ′ has one unique value y ₃ ′ at the boundary between the intermediate zone 14 and the outer zone 16.

[0110] As made from the bottom to the y → Z _2/2, as it goes y → Z _2/2 from the top lim y '= y _3', in _{lim y '= y 3' y} = Z 2/2, y ′ = Y ₃ ′

2. Viewed in cross section, the surface profile of contact lens 10 is either always convex or always concave throughout the optical zone. There is no local area where the concave direction changes sign. This mathematically means that there are no inflection points on the surface profile, since the second derivative of the surface profile does not change sign. Equivalently, this means that when any point on the surface profile moves across an area, the first derivative or tangent changes monotonically. The surface profile has no sharp corners or even rounded corners. The surface profile is smooth and has no undulations or undulations that suggest sharp or rounded corners.

3. The aspherical intermediate area 14 has an area 16 where the optical power deviates from that of the central area 12.
It is an area of gradient refractive power that continuously and monotonically changes up to the refractive power of. The exact shape of the aspheric surface provides the power profile for this purpose, since even slight deviations from the required shape can result in an unwanted power profile of the type shown in FIGS. 5 and 6. In order to calculate in detail. By providing such a continuous and monotonically varying power profile, the intermediate aspheric zone 14 acts as an optical zone of long depth of focus and also provides useful visual acuity for intermediate viewing distances.

Then, subject to the above three conditions, the dimensions of the zone can be calculated to maximize utilization of the pupil area for distance, near, and intermediate vision. At this step, all the above three conditions must be satisfied by the present invention. Failure to meet even one of the conditions can lead to visual confusion, which is common and noticeable in prior art lenses. These visual perturbations can be induced by edge effects at the boundaries of the constituent zones, or by the presence of an improper power profile resulting from a poorly characterized and uncontrolled aspheric surface. It may be triggered.

Unlike conventional concentric zone designs, the integration of the monorefractive power zone and the monotonic gradient power zone in the present invention, at any time, whether the object is in hyperopia or myopia,
Achieve higher utilization of pupil area, whether in intermediate vision or not. This maximizes the visual information available to the object at all viewing distances. The pupil size dependence is reduced because a larger portion of the pupil is always utilized. Properly configured, this is achieved without introducing unwanted edges or bifocal jump effects at the zone boundaries, as the intermediate zone 14 provides a seamless transition between single power zones. .

In another embodiment of the invention shown in FIG. 7, the lens is configured such that the diameters of the three zones provide a greater proportion of the pupil area due to near optical power. Except that it is similar to the preferred embodiment of FIG. Still middle area 2
4 has been calculated to meet all the conditions listed above for the present invention.

[0116]

[Table 6]

From the table above, it can be seen that for this configuration, for smaller pupil diameters, the proportion of the pupil area devoted to near vision power approaches the 50% level of prior art lenses.

However, it has been found that for the average user, this configuration does not provide the best visual performance over the full range of far, intermediate and myopic conditions. Useful clinical assessments must include not only an objective measure of visual performance as provided by a visual acuity assessment, but also a subjective grade of visual quality provided by the subject. The preferred embodiment shown in FIG. 1 has improved performance compared to the embodiment of FIG. This is because in order to consider the entire range of the visual distance, the central area of the near power is 5 of the pupil area.
Consistent with previous findings that it should correspond to less than 0%.

Another alternative embodiment of the present invention is shown in FIG. The illustrated contact lens 30 is a far-centered embodiment. In the preferred embodiment, the central zone 32 is a single power zone that provides the desired distance power. Outer zone 36 is a single power zone that provides near power. The intermediate section 34 is a gradient power aspherical section that provides a continuous power transition from the central section 32 to the outer section 36. In the embodiment of FIG. 8, the diameters of the various power zones are the same as in FIG. 7, but the order of distance power and near power is reversed.

[0120]

[Table 7]

Specific surface area designations for the sample power range are shown below. Again, for convenience, a frontal structure is assumed.

[0122]   Rear radius: 8.30mm   Center thickness: 0.08mm   Refractive index: 1.412   Bifocal addition refractive power: + 1.50D

[0123]

[Table 8]

The refractive power zone of the present invention is biocompatible with the eye and placed on the anterior or posterior surface of a soft contact lens made of a suitable soft material capable of supporting a surface of good optical quality. be able to. These soft materials are collectively referred to as "hydrogels".
And hydrous polymers and copolymers, silicone elastomers containing very little water and hydrous silicone polymers.
Examples of suitable hydrogel materials are polymers and copolymers of hydroxyethylmethylmethacrylate, ethoxyethylmethacrylate, diacetoneacrylamide, glycerylmethacrylate, methylmethacrylate.

The present invention can also be placed on the anterior or posterior surface of rigid contact lenses made from materials such as polymethylmethacrylate, various silicone acrylate polymers and fluoroacrylate polymers.

The lenses of the present invention can be manufactured by turning or molding techniques. With turning, turning equipment must be able to machine common surfaces, including spherical and aspherical profiles. One class of lathe with this capability is commonly referred to as a twin-axis or XY lathe because it allows the position of the cutting tool to be numerically controlled in two independent orthogonal directions. In the above coordinate system, the two orthogonal directions are the x-axis direction (the sagittal distance direction) and the y-axis direction (the chord diameter direction). Other lathes control the movement of the cutting tool by calibrating the movement of the cam follower. An aspherical surface is produced when the cam follower outlines a cam or template that acts as a master. However, this method first requires a method of manufacturing a cam that becomes the desired aspherical master. Therefore, these lathes do not have the flexibility to machine general aspherical surfaces at will.

The turning equipment must also provide a level of precision and accuracy that is sufficient to ensure that the specified continuity and power profile requirements of the present invention are met. It has been found that small deviations of half a micron from the optimum surface can result in the undesired power profile shown in FIGS. High precision XY lathes are available that provide this required level of control. Therefore, the XY lathe offers all the advantages of flexibility, precision and accuracy, thus providing a preferred turning method.

Another preferred method of making the present invention is by molding techniques. This method first requires the manufacture of a precision master part, which must then be faithfully duplicated into the final finished part. Master parts are often machined from a suitable durable metal using a very accurate XY lathe. The advantage of this method is that the efforts to accurately manufacture the aspherical surface of the present invention can be focused on the manufacture of very high quality metal masters.

In the method known as cast molding, no metal master is used to directly mold the contact lens. Rather, in a two-step molding process, a metal master is used to injection mold thousands of plastic masters from polypropylene or other suitable rigid polymeric material. Plastic parts are typically used only once to cast the final contact lens and then discarded. The contact lens is then hydrated in saline solution to the final shape.

[0130]   The following steps are required to design a metal master suitable for this casting method.

1. The shrinkage of injection molded plastic parts must be determined. The process used to make the examples of the present invention uses polypropylene, the shrinkage of which is about 1-5% depending on the grade of polypropylene used, the conditions of the injection molding process and other factors. .

2. The coefficient of swelling due to hydration of the selected contact lens polymer material must be determined. In this method, the coefficient of expansion of the polymeric material was found to be about 3-11%, depending on the composition of the polymer.

3. In this method, the metal master is produced by using a Moore (Bridgeport, CT) aspheric forming lathe to achieve the desired final shape. And
A metal master is used to injection mold plastic parts from polypropylene for final contact lens casting.

Contact lens 10 can also be manufactured using the method known as wet casting. A low molecular weight diluent may be added to cast the hydroxyethylmethacrylate (HEMA) mixture and the diluent removed during hydration to provide volume control during the hydration process. In the ideal wet cast case, swelling is zero. However, often less diluent is added so that some swelling occurs during the hydration process.
Lenses were manufactured using a range of diluent concentrations and in each case the results were good.

A range of diluent concentrations leads to a corresponding range of solids in the crude monomer mix. In this method, high solids formulations have been found to provide better lens performance than low solids formulations. However, low solids formulations appear to have some particular advantages. For example, (1) low solids monomer contains more diluent and has less swelling during polymerization and hydration as compared to high solids formulations. (2) Therefore,
The dimensions of the metal master of the low solids formulation are closer to those of the final contact lens because its coefficient of expansion is lower than that of the high solids formulation. (3) The yield of low solids formulations is higher when the coefficient of swelling itself is low, due to less variation in the polymer swelling process. Therefore, it would be preferable if a low solids formulation could be achieved that performed almost as well as a high solids formulation.

US Pat. Nos. 4,028,295, 5,63, which are incorporated herein by reference.
Wet cast UV absorbing HEMA polymers with a diluent concentration of about 33%, similar to the materials described in 7,726, 5,866,635 and 5,729,322 were selected as preferred materials. .

The present invention may also be sold as kit 40. Kit 40 includes a contact lens 42 constructed in accordance with the present invention in a sterile package and a bacteriostatic or sterile solution. The lens 42 can also be stored in a vial or blister package and includes a storage case 44. Kit 40 also includes at least one of cleaning solution 46 and disinfecting solution 48. The cleaning solution 46 can also include conventional cleaning solutions. Similarly, the antiseptic solution 48 can include conventional antiseptics. Kit 40 also includes a conventional wetting solution 50.

The present invention can also be used with durable contact lenses, frequently replaced contact lenses or day-use disposable contact lenses. Also, a custom made (MTO) contact lens may be implemented with the present invention. This custom contact lens has the following combinations: turning, casting, as described in US Pat. No. 5,110,278, the disclosure of which is incorporated herein by reference in the case of a toric surface. , Spherical or toric surface with injection molding or base curve molding and optical multifocal surface turned, colored, with print, U
It can also include any of the V-blocking materials. The present invention also includes US Pat. Nos. 4,976,533 (Knapp), 4,58, the disclosure of which is incorporated herein by reference.
2,402 (Knapp), 4,704,017 (Knapp), 5,414,4
77 (Jahnke) and 4,668,240 (Loshaek) and US Pat. Nos. 5,034,166 (Rawlings), 5,116,112 (Rawlings) and 5,302,978 (Evans). ) And colored toric surface toric surface multifocal contact lenses. More specifically, the present invention is directed to US Pat. No. 5,302,97, the disclosure of which is incorporated herein by reference.
An area adjacent to the user's iris can be included, including a dark, substantially light-absorbing power zone, as disclosed in No. 8. In addition, as disclosed in No. 09 / 298,141 filed April 23, 1999 in the name of M. Quinn and B. Atkins, the disclosure of which is incorporated herein by reference, Lens patterns, pad printing processes and mixtures of inks and binders can be used with the lenses of the present invention. For example, a pad printing method may be used that uses a flexible pad that is pressed against the lens surface for patterning. The ink will include a pigment, an enhancing paste and an activating solution. The present invention also provides a UV blocker as disclosed in 09 / 121,071 filed on July 21, 1998 in the name of Hermann Faubl, the disclosure of which is incorporated herein by reference. It can also be realized.

US Pat. Nos. 4,976,533, 4,582,402 or 4,704
, 017, a colorant is added to the non-hydrated lens,
The lens is print hardened and then hydrated.

The present invention also includes US Pat. No. 5,02, the disclosure of which is incorporated herein by reference.
Inventions relating to toric surface lenses described in Nos. 0,898, 5,062,701 and 4,976,533 can be used. It is desirable to provide an optimal optical correction for a patient's refractive error, regardless of whether the patient has presbyopia. Therefore, it is desirable to use the present invention with toric surface contact lenses if there is a significant astigmatic component in addition to refractive disorders in presbyopia patients. Such a combination corrects the patent's complete refractive error and also corrects the loss of near focusing power that occurs in presbyopia. In most toric surface contact lenses, since the toric surface is disposed on the front surface or the rear surface, from the viewpoint of economical manufacturing, the bifocal element of the present invention is a non-toric surface, that is, a toric surface. It is convenient (although not required) to place it on the opposite side. In a bituric surface contact lens, both the anterior and posterior surfaces are toric surfaces, and the bifocal element may be on either surface. To stabilize the bifocal toric surface combination lens, any method of stabilizing the toric surface lens may be used, such as prism ballasts and thin zones.

10 and 11 show a useful and preferred toric surface lens 200 having a toric surface on the front or back surface of the lens of the present invention. The preferred embodiment 200 is
It has an edge lift 202 of 0.030 mm and a perimeter thickness 204 of 0.150 mm. The lens 200 includes a corner thickness 206 of 0.380 mm. Referring to FIG. 11, the upper lenticular portion 210, the optical zone 212 and the carrier 214 are shown. In the preferred embodiment, the lens 200 has a trim width 220 of 1.0 mm
And a corner angle 222 of °. Of course, these dimensions can be varied, as will be appreciated by those skilled in the art.

The present invention can also include methods of using contact lenses constructed according to the present invention. The method includes placing a contact lens over the user's pupil. Contact lenses will be constructed in accordance with the present invention.

The present invention also includes a method of prescribing a combination of contact lens structures, each constructed according to the present invention. For many users, the combination of such structures can further enhance the range of visual performance beyond that achieved with a single structure of the present invention. A method of use known as monobition is to prescribe both monoculars with conventional single vision lenses of different refractive power. Usually, a distance vision prescription single vision lens is placed in the user's dominant eye, and a near vision prescription lens is placed in the non-dominant eye (However, this order may be reversed depending on the subject. It may be preferable to place a lens of refractive power in the non-dominant eye). This method can provide reasonable levels of distance and near vision, but only one eye at a time. In fact, many users find the overall vision level unacceptable in monovision because this method confuses binocular vision and does not account for vision at intermediate viewing distances.

The combination formulation of the present invention can minimize these drawbacks that limit success in monovision. In one such combination method, a lens having a relatively small central zone of near power is prescribed for one eye. Although such a structure for this eye does not enhance myopia, the central zone is still large enough to provide a small but useful level of myopia. On the other hand, the distance vision in such a structure is relatively enhanced. In this same manner, a lens of the invention having a relatively high near power central zone is prescribed to the other eye. For eyes with this structure, near vision is relatively enhanced and far vision is useful, although not enhanced. Usually, a lens with a relatively small central zone of near power is prescribed for the dominant eye, and a lens with a relatively large central zone is prescribed for the non-dominant eye, but in each case the reverse order is preferred. There is also.

This combination prescription method has the great advantage of providing a much higher level of binocular vision than is possible with the monovision method, since useful levels of distance and near vision are simultaneously provided in both eyes. Have. This method also has the advantage of providing binocular mid-range vision to both eyes due to the gradient power intermediate zone present in the lens of each eye. Thus, this combination prescription method of the present invention significantly reduces or eliminates both major drawbacks to the monovision method.

In addition to contact lenses and intraocular lenses, the optical elements of the invention can be incorporated into the cornea itself using the technique of excimer laser refractive surgery.

In a form of laser surgery known as photorefractive keratectomy or RPK, the anterior surface of the cornea is reformed by a laser to alter the anterior curve of the cornea and thus the final refractive power. This technique removes the corneal epithelium. Therefore, PRK is considerably painful until the epithelium is completely regenerated.

General methods and devices for laser engraving the cornea using PRKs are known and include the correction of astigmatic presbyopia using PRKs applying the optics and considerations described herein. Achieving presbyopia correction would be a routine skill in the art. US Pat. No. 5,395,356 to King et al., Issued Mar. 7, 1995, describes such a method and apparatus, which is incorporated herein by reference. King et al. In reprofiling the cornea to create at least one region with a different focus (“additional” power relative to the patient's normal prescription), thereby accommodating near vision conditions. Discloses that correction of presbyopia is achieved by assisting the eye. King et al. Disclose that photoablation of the cornea creates at least one region of different curvature to allow the eye to adapt to nearby objects. This "summing" region is preferably located near the center of the optical zone, preferably in the adjacent upper portion of the stroma, located in or just below the Bowman's membrane. The disclosed device includes laser means and beam shaping means disposed between the laser means and the corneal surface for applying a predetermined ablation profile to the cornea.
The system may also include feedback control means for measuring the efficacy of the laser during surgery and controlling the laser. The beam shaping means is an aperture,
Beam-shaping stop means, for example, may be included alone or in combination with the beam-shaping window and may be photodegradable or otherwise absorptive in order to provide a predetermined profile of resistance to laser radiation. Can also include a gradually changing mask.

A mask used to correct presbyopia has also been described by Vinciguerra et al. To correct 3 presbyopia of 3 patients (Journal of Refracti).
ve Surgery, Vol. 14, January / February 1998, pp. 31-37). In this case, a mask consisting of a movable diaphragm formed by two blunt blades was used to ablate a crescent-shaped area 10 to 17 μm deep beneath the center of the pupil, resulting in a steep corneal curvature in that area. ing. The Aesculap-Meditec MEL excimer laser is used (Aesculap Meditec, Heroldsberg, Germany).

Other techniques for reprofiling the anterior surface of the cornea are known. September 1999
International application WO99 / 4449 with VISX Corporation as the assignee, published on October 10
2 describes an ophthalmic surgery system and a method of treating presbyopia by performing ablative photolysis of the corneal surface. A variable aperture, such as a variable width slit and offset image of the variable diameter iris diaphragm, is scanned in a preselected pattern to perform ablative engraving of a predetermined portion of the corneal surface. The scan is performed to ablate an optical zone sized to fit the patient's pupil with the peripheral transition zone outside the pupil. The shape of the ablated optical zone differs from the shape of the final optical correction to the anterior surface of the cornea. The optical zone corrects near vision at the center and far vision at the periphery. A moveable image displacement mechanism allows radial displacement and angular rotation of the profiled beam exiting the variable aperture. This reference discloses a large area treatment with a laser having a beam narrower than the treatment area and can be used in the treatment of many conditions associated with presbyopia, such as hyperopia, hyperopic astigmatism and malrefractive aberrations.

Also, many patients may have astigmatism in addition to presbyopia, in which case
The refractive powers for distance, near and intermediate vision must be combined with cylinder correction. Vinciguerra et al., Journal of Refractive Surgery, Vol. 15,
March / April (suppl.) 1999, pp. S186-96 uses the Nidek EC-5000 excimer laser to ablate half of the amount of cylinder along the steepest meridian, It describes the correction of hyperopic astigmatism by ablating the other half along a flat meridian. The spherical equivalent was then corrected. Nidek EC-
Later versions of 5000 software (version 3.0) removed less tissue.

Recently, the PRK procedure has generally been superseded by laser-assisted corneal curvature plasty, or LASIK. In this method, the front surface of the corneal tissue is incised into a flap shape by a microkeratome, and then the inner surface of the cornea is created and exposed. Then, after the newly exposed surface is re-formed by a laser, the corneal flap is restored. There is little pain associated with LASIK because the corneal epithelium is preserved.

As an alternative to the single vision refraction correction provided by conventional techniques, an excimer laser may be used to engrave the optical surface of the invention on the cornea of a presbyopia patient. The optical considerations for such multifocal corneal reshaping are similar to the considerations of placing the optical surface of the present invention on the anterior surface of a contact lens.

It is within the skill of the art to apply the optical system of the present invention to the LASIK approach with the considerations described herein, and there are commercially available instruments for that purpose. LASIK
The method is described in Bura, published August 10, 1999, which is incorporated herein by reference.
U.S. Pat. No. 5,935,140 to tto. The disclosed method involves making a thin semicircular incision in the cornea to form the epidermal layer, which is left attached to the cornea at the region of the top of the head to form the flap. The skin layer is flipped up to expose the underlying surface and exposed to the desired ablation. After that, the epidermis layer is put back on the surface of the lower layer and deposited. By forming a flap near the parietal region with the hinge area of the tether, the flap that is flipped up during surgery and then returned is smoothly continuous with the rest of the cornea due to the effect of blinking and gravity. . This promotes expansion of the epidermal layer and center alignment, enhancing the effectiveness of the ablation process. The method of the present invention also enhances ease and convenience to the practitioner performing the method.

One of the differences between applying a given optical principle to correct hyperopia by laser surgery and applying the same optical principle to correct hyperopia by the use of contact lenses is In order to make the cornea a steep angle by engraving, the cornea itself must be ablated at a steep angle, and there is a risk of corneal damage as a result of steep ablation. This may be especially true if a large ablation zone is desired to reach the large visual zone. Developments in laser ablation profiles for hyperopia have been developed to address this issue, some of which have been published by Anschutz et al., Journal of R.
efractive Surgery, Vol. 14, No. 2 (Suppl.), April 1998, pp.
Discussed in 5192-5196.

Another reference dealing with general hyperopia, myopia and astigmatism considerations both in terms of apparatus and method is an apparatus for performing corneal refractive surgery by ablating a portion of the corneal surface. Described, Laser Sight, published May 7, 1998
International application WO98 / 18522 with Technologies Inc. as the assignee. The device includes a pulsed laser for emitting a pulsed output of a light beam. A scanning mechanism scans the output beam, and the output beam is operatively associated with the scanning mechanism to direct the output beam onto a given surface defined by a mathematically derived ablation layer boundary curve for each ablation layer. You can scan with. The controller is operatively associated with the scanning mechanism to integrate the edges of the ablation layer boundary curve to more closely match the desired ablation shape so that the center point of the output beam is within the ablation layer boundary curve. , Directing the output beam to a predetermined surface on and outside the ablation layer boundary curve but within a predetermined distance from the closest point on the ablation layer boundary curve. Such a device can be programmed to provide the optical system of the present invention.

The multifocal optical surface or element of the present invention offers several advantages over multifocal contact lenses when incorporated into a LASIK (or PRK) approach. Unlike contact lenses, which cannot be precisely centered or are slightly offset with each blink, the element to be engraved will always remain in its original aligned position. Also, because each cornea must be individually reshaped, the constraints of mass production of contact lenses do not apply. Therefore, "one size fits all"
Each eye can receive the equivalent of a customized multifocal prescription, without the need for a traditional approach. Finally, the contact lens aspect of the present invention is for selecting patients so that only those patients who would benefit from the particular embodiment of the present invention (the patient being able to model many of them) would subsequently undergo laser treatment. Can also be used for. Experience with contact lenses prior to laser treatment allows the patient's visual system to be more easily adapted to the sculpted optics.

PRK and LASIK are the most commonly practiced techniques for corneal engraving, but other techniques have also been used, in the future reshaping the cornea or other optical surfaces on the pupil. New techniques for proximity may be developed. For example, 1
US Patent No. 5,618,284 to Sand, issued April 8, 997,
A method of reshaping the cornea by thermal contraction of collagen in the cornea by the application of coherent infrared is described. The radiation is delivered at a wavelength of approximately 1.80 microns to 2.55 microns, for a time and intensity sufficient to cause collagen to contract without causing ablation of corneal tissue, causing the cornea to contract into different shapes. The multifocal optical system of the present invention can be applied not only to the more general laser engraving technique, but also to such technique.

Typical zone dimensions for a laser engraving multifocal element would be similar to those shown in Table 2 for the preferred embodiment as a contact lens. However, the dimensions specific to a given eye can vary somewhat from Table 2 due to the freedom to provide a customized prescription. The outermost diameter of the optical zone is usually about 6 in the case of LASIK.
． Although less than or equal to 5 mm, this dimension is on the order of 8 mm or 9 mm for contact lenses, and is often much larger.

Otherwise, the same considerations for the calculation of specific zones that apply to the contact lens surface also apply to laser corneal reshaping. In the case of corneal reshaping, either a near-center or far-center structure can be selected, but like the contact lens, a near-center structure is preferable. The near-centric structure also has the advantage that the final corneal thickness profile of the reshaped multifocal region differs by only a few microns from the thickness profile obtained by the same distance refractive correction from the corresponding monovision technique. Have.

The calculations using equations (1)-(47) describing the continuity requirement of the surface profile at the zone boundaries and the contact lens surface also apply to the reshaping of the corneal surface. Therefore, in the near-center structure, the apex radius r ₃ of the third or outermost zone is the same radius as used in the conventional method for single vision distance correction. The central zone apex radius r ₁ is steeper as it provides the desired bifocal “additive” power. Then, the remaining variables including the variables of the aspherical area are calculated from the equations (1) to (47).

By trial wearing appropriate multifocal contact lenses prior to the surgical procedure, the subjective acceptance of the visual acuity provided by the multifocal element can be readily determined in advance. If the accuracy of laser reshaping is at least as accurate as the contact lens manufacturing process, the visual acuity of the laser reshaping corneal multifocal element should be equal to or better than that associated with multifocal contact lenses. .

Accordingly, one embodiment of the present invention reprofiles the cornea to
A method of providing the eye with multifocal ability for correcting presbyopia. The method comprises providing a laser operable to deliver ablative laser radiation to the cornea, and selectively exposing the cornea to the ablative radiation to provide a first viewing area, a first area. A second viewing area surrounding the second viewing area and a third viewing area surrounding the second viewing area,
The first viewing zone has a substantially single power, the second viewing zone has a range of powers, and the third viewing zone differs from the first single power. A second, substantially single refracting power, at least one of the first, second and third viewing zones having an aspherical surface and two other zones having a spherical surface; Creating second and third viewing zones.

In a second embodiment, the invention relates to a method of changing the curvature of the cornea for the correction of presbyopia. In this method, a thin layer-shaped incision extending like an incomplete circle is made on the surface of the cornea to form a surface layer connected to the cornea at a portion near the parietal surface, and the surface layer is turned up to form the lower surface of the cornea. Is exposed and ablation or removal of tissue is performed on the underlying surface to change the curvature of the cornea to alter the first viewing zone, the second viewing zone surrounding the first zone and the second viewing zone. A third viewing zone surrounding the viewing zone of, the first viewing zone having a substantially single refractive power and the second viewing zone having a range of refractive powers,
The third viewing zone has a second substantially single refractive power different from the first single refractive power, and at least one of the first, second and third viewing zones has an aspherical surface. Creating a first, a second and a third viewing zone, the other two zones having a spherical surface, and bringing the surface back onto the underlying surface.

In a third embodiment, the invention relates to an optical surface for correcting presbyopia, which is close to the pupil. The optical surface includes a first viewing area, a second viewing area that surrounds the first area, and a third viewing area that surrounds the second viewing area, where the first viewing area is the first substance. Has a single refractive power, the second viewing zone has a range of refractive powers, and the third viewing zone has a second substantially different refractive power from the first single refractive power. It has a single refractive power and at least one of the first, second and third viewing zones has an aspherical surface and the other zone has a spherical surface. Preferably, the points on the optical surface are defined by the equation:

[0166]

[Equation 30]

Where Z ₁ is the chord diameter of the central first viewing zone, Z ₂ is the chord diameter (outer diameter) of the second viewing zone, and Z ₃ is the third viewing zone. The chord diameter of the zone, Z ₁ is 1.2 mm
2.1 mm, Z ₂ is 2.0 mm to 4.8 mm, Z ₃ is less than 8 mm,
The specific values assigned to the variables r _i , p _i , ε _i , η _i and Z _i (i = 1, 2 and 3) are selected to provide the patient with the desired refractive index and presbyopia correction. More preferably, p ₁ = p ₃ = 1 and η ₁ = η ₃ = 0, and in the case of i = 2, η ₂ = 0 is arranged by appropriate choice of other variables. In particular, equation (45)
Is satisfied, then η ₂ = 0 is satisfied.

[0168]

[Equation 31]

Where x ₁ is the sagittal distance at the boundary between the first viewing area and the second viewing area, and x ₃ is the sagittal distance at the boundary between the second viewing area and the third viewing area. , Y ₁ and y ₃ are the half chord diameters at these same boundaries and y ₁ ′ and y ₃ ′
Is the tangent to the surface profile of the cross section at these same boundaries.

With respect to the first, second and third embodiments, it is preferred that the first viewing zone has near vision correcting power and the third viewing zone has far vision correcting power. More preferably, the first viewing area covers the central area of the pupil. More preferably, the first and third viewing zones are spherical and the second zone is aspherical.

Regarding the specific dimensions of the viewing zone, or visual zone, the second visual zone is an annulus concentric with the first visual zone and the second visual zone is between 1.2 mm and 2.1 mm. It has an inner diameter and an outer diameter of 2.0 mm to 4.8 mm. More preferably, the second visual zone has an inner diameter of 1.5 mm to 1.9 mm and an outer diameter of 2.3 mm to 3.0 mm. It is also preferred that the second visual zone is adjacent to the first and third viewing zones. Within these dimensions, the first viewing zone covers less than 50% of the pupil area under indoor ambient lighting conditions, and more preferably the first viewing zone is under indoor ambient lighting conditions. It is preferable to cover 38% or less of the area.

Similarly, the second viewing zone is continuous from the first single refractive power adjacent to the first viewing zone to the second single refractive power adjacent to the third viewing zone. It is preferable to have a certain range of refractive power that changes substantially monotonically. Preferably the surface profile is
The first viewing zone surface has a first tangent line adjacent to the second viewing zone surface and the second viewing zone surface adjacent to the first viewing zone surface has the same tangent line. Similarly, it is preferred that the third viewing zone surface has a second tangent line adjacent to the second viewing zone surface, and the second viewing zone surface adjacent to the third viewing zone surface has the same tangent line. More preferably, the surfaces of the first, second and third viewing zones have a constant unidirectional concave shape.

In a fourth embodiment, the invention relates to a method of reshaping the cornea to obtain the optical surface of the third embodiment. The method involves reforming the anterior or underlying surface of the cornea by ablation or collagen contraction, which employs excimer laser, surgical laser, water cutting, fluid cutting, liquid cutting or gas cutting techniques. It is carried out by Corneal reshaping can also include placing a contact lens having desired optical properties on the cornea to obtain this optical surface on the artificially created anterior corneal surface. Similarly, corneal reshaping can include implanting a lens with desired optical properties into the cornea.

These embodiments of the method of profiling or reshaping the cornea using a laser to correct presbyopia can be carried out using a laser system, which is also within the scope of this invention. One embodiment of a laser surgical system is in the form of an ophthalmic surgical system for reprofiling the cornea to provide the eye with multifocal ability to correct presbyopia. In this embodiment, the system comprises a laser operable to deliver ablative laser radiation to the cornea, and a portion of the cornea is selectively exposed to the ablative radiation to provide a first visual field on the cornea. An area, a second viewing area on the cornea surrounding the first area and a third viewing area on the cornea surrounding the second viewing area, the first viewing area being substantially a single A second viewing zone having a range of powers and a third viewing zone having a second substantially single power different from the first single power. For creating first, second and third viewing zones, wherein at least one of the first, second and third viewing zones has an aspherical surface and the other two zones have spherical surfaces A laser control system.

In another aspect, a laser system includes a laser assembly for projecting radiation onto a selected area of an exposed surface of the cornea to ablate the selected area to a certain depth, and radiation projected onto the area. Of the corneal ablation, thereby controlling the depth of corneal ablation, the first viewing zone, the second viewing zone surrounding the first zone and the second viewing zone surrounding the first viewing zone. The third viewing zone has a substantially single refractive power, the second viewing zone has a range of refractive powers, and the third viewing zone has a first viewing zone. A second substantially single power different from a single power, at least one of the first, second and third viewing zones having an aspheric surface and the other two zones A laser system controller for creating first, second and third viewing zones having spherical surfaces.

In yet another aspect, a laser system includes a radiation source for emitting a laser beam of ablative radiation and a beam shaping means for receiving the beam and selectively transmitting at least a portion of the beam to the cornea. And applying a beam to the cornea to remove a selected amount of corneal tissue from the region of the optical zone of the cornea by ablative radiation, thereby enclosing a first viewing zone, a second zone surrounding the first zone. A third viewing zone surrounding the second viewing zone and the second viewing zone having a substantially single refractive power and the second viewing zone having a range of refractive powers. And the third viewing zone has a second substantially single refractive power different from the first single refractive power, and at least one of the first, second and third viewing zones First, second and third viewing zones, one having an aspherical surface and the other two zones having a spherical surface And a laser control system for forming a reprofiled region having a photorefractive keratectomy system.

In addition, the present invention relates to methods of improving the desired presbyopia correction and acclimatizing the patient to the final presbyopia correction prior to corneal reshaping. The method comprises a first viewing zone in the central area of the pupil, a second viewing zone surrounding the first area and a third viewing zone surrounding the second viewing zone, the first viewing zone The area has a first substantially single power for near vision correction, the second viewing area has a range of powers, and the third viewing area has a first single power. A second substantially single power different from the power, the second power is for distance vision correction, the first and third viewing zones have spherical surfaces, and the second Providing the patient with a pair of multifocal contact lenses, each of which includes a first, second and third viewing zone, the areas of which have aspheric surfaces. Preferably, the patient is differentiated for the dominant and non-dominant eyes separately in steps as necessary to achieve presbyopia correction that is satisfactory for the patient at near, far and intermediate distances. Provided is a replacement multifocal contact lens having one power, a different second power, a different Z ₁ or Z ₂ dimension or a combination of different first and second powers and zone dimensions. After the patient has worn the lens and adapted to vision correction with a multifocal lens, the cornea is reformed to provide a refractive power correction profile corresponding to the refractive power of the contact lens that provided satisfactory visual correction for the patient. Achieve the optical surface.

For example, in order to improve the patient's visual acuity by providing a replacement lens, it is proposed that the binocular fit that provides an acceptable visual acuity to the individual patient's requirements is only slightly deviated. In order to improve distance vision, it is proposed to use a hand-held lens to add a slight negative refractive power to the dominant eye monocularly. Then, it is determined whether the distance vision and the near vision with both eyes are acceptable. If acceptable, add this negative power to the distance power of the dominant eye contact lens. Alternatively, the additive refractive power of the first viewing zone is monotonically reduced with respect to the dominant eye to provide more acceptable vision for the patient.

In order to improve myopia, it is proposed to use a hand-held lens to apply a small positive power to the non-dominant eye monocularly. Then, it is determined whether the distance vision and the near vision of both eyes are acceptable. If acceptable, add this positive power to the distance power of the non-dominant eye contact lens. Alternatively, the additive refractive power of the lens for the non-dominant eye may be increased monocularly. The gradual combination of these adjustments to the contact lens provided to the patient over a period of days to weeks provides satisfactory vision over myopia, intermediate vision and distance vision for a variety of real life activities. A combination of multifocal lens corrections to provide to the patient can be reached. After the patient has worn the contact lens for about a week or longer to adapt to multifocal corrective vision, the patient has remodeled the cornea and has been found to be very satisfactory for the patient. A corrective procedure may be performed that provides an optical surface that corresponds to the force profile.

Similarly, contact lenses having the optical properties of one of the embodiments of the present invention can also be used to screen patients for corneal reprofiling. In other words, another aspect of the invention includes a method of selecting a patient that is a desirable candidate for corneal sculpting to correct presbyopia. The method comprises a first viewing zone in the central area of the pupil, a second viewing zone surrounding the first area and a third viewing zone surrounding the second viewing zone, the first viewing zone The area has a first substantially single power for near vision correction, the second viewing area has a range of powers, and the third viewing area has a first single power. A second substantially single power different from the power, the second power is for distance vision correction, the first and third viewing zones have spherical surfaces, and the second Providing the patient with a pair of multifocal contact lenses, each of which includes a first, second and third viewing zone, the areas of which have aspheric surfaces. Preferably, if the contact lens does not provide acceptable vision correction to the patient, the patient will be presbyopia that is satisfactory to the patient at near, far and intermediate distances, separately for the dominant and non-dominant eyes. Different first powers, different second powers, different Z ₁ or Z ₂ dimensions or different first and second powers and zones, stepwise as necessary in an attempt to achieve correction. A replacement multifocal contact lens having a combination of dimensions is provided. Then, if satisfactory vision correction is achieved at near, far and intermediate distances, the patient is selected as a candidate. A refractive correction profile corresponding to the refractive power of the contact lens that provided the patient with satisfactory vision correction by reshaping the cornea after the selected patient has worn the lens and adapted to the vision correction by the multifocal lens. To achieve an optical surface.

Patients may have vision corrected to near / 2.0 visual acuity at near, intermediate and far distances, but vision correction may not be satisfactory to the patient. It should be understood that satisfactory vision correction is a very subjective measure for individual patients. Thus, as with changes in eye prescription, vision correction can be a compromise between vision and comfort for the patient. Measurable 2.0
Even if a /2.0 correction can be provided objectively, the blurring, distortions and shadowing that may cause the patient to be less than satisfied with the vision correction of a multifocal contact lens is not uncommon. Sometimes patients can adapt to multifocal contact lenses in a short, short period of about a week, and these patients are
It is a good candidate for corneal engraving of contact lens refractive power correction profiles. On the other hand, some patients do not adapt to corrected vision even after a few weeks and do not think that their vision has been corrected to a satisfactory degree by trial of multifocal contact lenses. These latter patients can be excluded from the population of potential candidates for corneal engraving of optical surfaces that correspond to those of trial multifocal contact lenses. It is up to the individual practitioner and the patient at what point in the trial when he or she fails to adapt to a particular lens correction, at which point he determines that the patient has worn the lens for a sufficient period of time. The number of trial contact lenses that a patient can wear and the number of trials in order to exclude patients who may not be promising candidates for corneal remodeling, in determining that they have attempted lens replacement for a sufficient period of time, and the number of trials. Economically considered by.

The embodiments described above and shown herein are illustrative and not limiting. The scope of the invention is indicated by the appended claims rather than the foregoing description and accompanying drawings. The present invention may be embodied in other specific forms without departing from the essence of the invention. For example, additional zones may be incorporated into the design. In particular, one further embodiment will include a further aspherical zone and an outer spherical zone, such that the optical surface comprises three spherical zones and two aspherical zones. The dimensions of the various areas would have to be sized to fit within the user's pupil area. Modifications that fall within the scope of the claims are intended to be embraced herein.

[0183]   All references disclosed above are incorporated herein by reference.

[Brief description of drawings]

FIG. 1 is a front view of the optical portion of a contact lens constructed according to one preferred embodiment of the present invention.

[Fig. 2]   3 is a graph showing a cross section of a lens of the related art.

[Figure 3]   2 is a graph showing a cross section of the preferred embodiment shown in FIG. 1.

[Figure 4]   3 is a graph showing optical power as a function of chord diameter for the preferred embodiment.

[Figure 5]   6 is a graph showing a lens having an incorrect power profile.

[Figure 6]   6 is a graph showing another lens having an incorrect power profile.

FIG. 7 is a front view of the optical portion of a contact lens constructed in accordance with another preferred embodiment.

FIG. 8 is a front view of the optical portion of a contact lens constructed in accordance with another preferred embodiment.

[Figure 9]   FIG. 6 shows a kit constructed according to another preferred embodiment.

FIG. 10 is a front view of a contact lens constructed in accordance with yet another preferred embodiment.

FIG. 11   11 is a cross-sectional view of the embodiment of FIG.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) A61F 9/00 540 (81) Designated country EP (AT, BE, CH, CY, DE, DK, ES, FI) , FR, GB, GR, IE, IT, LU, MC, NL, PT, SE, TR), OA (BF, BJ, CF, CG, CI, CM, GA, GN, GW, ML, MR, NE) , SN, TD, TG), AP (GH, GM, KE, LS, MW, MZ, SD, SL, SZ, TZ, UG, ZW), EA (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), AE, AG, AL, AM, AT, AU, AZ, BA, BB, BG, BR, BY, BZ, CA, CH, CN, CR, CU, C , DE, DK, DM, DZ, EE, ES, FI, GB, GD, GE, GH, GM, HR, HU, ID, IL, IN, IS, JP, KE, KG, KP, KR, KZ, LC, LK, LR, LS, LT, LU, LV, MA, MD, MG, MK, MN, MW, MX, MZ, NO, NZ, PL, PT, RO, RU, SD, SE, SG, SI , SK, SL, TJ, TM, TR, TT, TZ, UA, UG, UZ, VN, YU, ZA, ZW

Claims (77)

[Claims] 1. A method of reprofiling the cornea to provide the eye with a multifocal ability to correct presbyopia, the method comprising providing a laser operable to deliver ablative laser radiation to the cornea. And selectively exposing the cornea to the ablative radiation to provide a first viewing zone, a second viewing zone surrounding the first zone and a third viewing zone surrounding the second viewing zone. Wherein the first viewing zone has a substantially single refractive power, the second viewing zone has a range of refractive powers, and the third viewing zone is the first viewing zone. A second substantially single power different from the single power of at least one of the first, second and third viewing zones having an aspherical surface, and the other two powers of the other two. Creating the first, second and third viewing zones, wherein the zones have a spherical surface. 2. The method of claim 1, wherein the first viewing zone has near vision correction power and the third viewing zone has far vision correction power. 3. The method of claim 2, wherein the first viewing zone covers a central zone of the pupil. 4. The method of claim 3, wherein the first and third viewing zones are spherical and the second zone is aspherical. 5. The second visual zone is a circular ring concentric with the first visual zone, and the second visual zone has an inner diameter of 1.2 mm to 2.1 mm and 2.0 mm to 4 mm.
． The method according to claim 4, having an outer diameter of 8 mm. 6. The inner diameter of the second visual zone is between 1.5 mm and 1.9 mm and 2.
The method of claim 5 having an outer diameter of 3 mm to 3.0 mm. 7. The second viewing area is adjacent to the first and third viewing areas,
The method of claim 3. 8. The second single viewing zone from the first single refractive power adjacent to the first single viewing zone to the second single single power to adjacent the third single viewing zone. 8. The method of claim 7, having a range of refractive power that continuously and substantially monotonically varies up to. 9. The first viewing zone surface has a first tangent that is adjacent to the second viewing zone surface, and the second viewing zone that is adjacent to the first viewing zone has the same tangent. 9. The method of claim 8, comprising: 10. The third viewing area surface has a second tangent line adjacent to the second viewing area surface, and the second viewing area adjacent to the third viewing area has the same tangent line. 9. The method of claim 8, comprising: 11. The method of claim 8, wherein the surfaces of the first, second and third viewing zones have a constant unidirectional concave shape. 12. The method of claim 3, wherein the first viewing zone covers less than 50% of the pupil area at ambient ambient lighting conditions. 13. The method of claim 3, wherein the first viewing zone covers less than 38% of the pupil area at ambient ambient lighting conditions. 14. A method for changing the curvature of the cornea to correct presbyopia, which comprises making a thin layer-shaped incision extending like an incomplete circle on the surface of the cornea, and making a cornea near the parietal region. Forming a connected surface layer, exposing the lower surface of the cornea by flipping the surface layer, by changing the curvature of the cornea by performing tissue ablation or removal to the lower surface,
A first viewing zone, a second viewing zone surrounding the first viewing zone and a third viewing zone surrounding the second viewing zone, the first viewing zone being substantially single Second refraction power having a range of refraction powers, and the third refraction power is different from the first single refraction power. The first, second and third viewing zones have an aspherical surface and the other zone has a spherical surface,
Creating a first, second and third viewing zone, and returning the surface layer over the underlying surface. 15. The method of claim 14, wherein the first viewing zone has near vision correction power and the third viewing zone has distance vision correction power. 16. The method of claim 15, wherein the first viewing zone covers a central zone of the pupil. 17. The method of claim 16, wherein the first and third viewing zones are spherical and the second zone is aspherical. 18. The second visual zone is a circular ring concentric with the first visual zone, and the second visual zone has an inner diameter of 1.2 mm to 2.1 mm and a diameter of 2.0 mm.
18. The method of claim 17, having an outer diameter of 4.8 mm. 19. The second visual zone has an inner diameter of 1.5 mm to 1.9 mm and 2
． 19. The method of claim 18, having an outer diameter of 3 mm to 3.0 mm. 20. The method of claim 16, wherein the second viewing area is adjacent to the first and third viewing areas. 21. The second viewing zone from the first single refractive power adjacent to the first viewing zone to the second single refractive power adjacent to the third viewing zone. 21. The method of claim 20, having a range of refractive power that continuously and substantially monotonically varies up to. 22. The first viewing zone surface has a first tangent line adjacent to the second viewing zone surface, and the second viewing zone adjacent to the first viewing zone has the same tangent line. 22. The method of claim 21, comprising: 23. The third viewing area surface has a second tangent line adjacent to the second viewing area surface, and the second viewing area adjacent to the third viewing area has the same tangent line. 22. The method of claim 21, comprising: 24. The method of claim 21, wherein the surfaces of the first, second and third viewing zones have a constant unidirectional concave shape. 25. The method of claim 16, wherein the first viewing zone covers less than 50% of the pupil area at ambient ambient lighting conditions. 26. The method of claim 16, wherein the first viewing zone covers less than 38% of the pupil area at ambient ambient lighting conditions. 27. The ablation is performed by applying an excimer laser, surgical laser, water cutting, fluid cutting, liquid cutting or gas cutting technique.
The method described. 28. An optical surface proximate to the pupil for correcting presbyopia, comprising: a first viewing zone, a second viewing zone surrounding the first zone and the second viewing zone. An enclosing third viewing zone, the first viewing zone having a first substantially single power, the second viewing zone having a range of powers, and The three viewing areas
A second substantially single power different from the first single power, at least one of the first, second and third viewing zones having an aspheric surface, and An optical surface whose area has a spherical surface. 29. The optical surface of claim 28, wherein the first viewing zone has near vision correction power and the third viewing zone has distance vision correction power. 30. The first viewing zone spans the central zone of the pupil.
The optical surface described. 31. The optical surface of claim 30, wherein the first and third viewing zones are spherical and the second zone is aspherical. 32. The second visual zone is a circular ring concentric with the first visual zone, and the second visual zone has an inner diameter of 1.2 mm to 2.1 mm and a diameter of 2.0 mm.
The optical surface of claim 31, having an outer diameter of 4.8 mm. 33. The second visual zone has an inner diameter of 1.5 mm to 1.9 mm and 2
． 33. The optical surface of claim 32, having an outer diameter of 3 mm to 3.0 mm. 34. The optical surface of claim 30, wherein the second viewing area is adjacent to the first and third viewing areas. 35. The second viewing zone from the first single refractive power adjacent to the first viewing zone to the second single refractive power adjacent to the third viewing zone. 35. The optical surface of claim 34 having a range of refractive power that continuously and substantially monotonically varies up to. 36. The first viewing zone surface has a first tangent that is adjacent to the second viewing zone surface, and the second viewing zone that is adjacent to the first viewing zone is the same tangent. 31. The method of claim 30, comprising: 37. The third viewing zone surface has a second tangent line adjacent to the second viewing zone surface, and the second viewing zone adjacent to the third viewing zone surface has the same tangent line. 31. The method of claim 30, comprising: 38. The method of claim 30, wherein the surfaces of the first, second and third viewing zones have a constant unidirectional concave shape. 39. The optical surface of claim 30, wherein the first viewing area covers less than 50% of the pupil area under indoor ambient lighting conditions. 40. The optical surface of claim 30, wherein the first viewing area covers less than 38% of the pupil area under indoor ambient lighting conditions. 41. An optical surface proximate to a pupil for correcting presbyopia, comprising: a first viewing zone, a second viewing zone surrounding the first zone and the second viewing zone. An enclosing third viewing zone, the first viewing zone having a first substantially single power, the second viewing zone having a range of powers, and The three viewing areas
A second substantially single power different from the first single power, at least one of the first, second and third viewing zones having an aspheric surface, and Has a spherical surface, and the point on the optical surface is represented by the following formula: Where x is the sagittal distance of a point on the surface, y is the half chord diameter,
Z ₁ is the central chord diameter of the first viewing zone, Z ₂ is the chord diameter (outer diameter) of the second viewing zone, and Z ₃ is the chord diameter of the third viewing zone. Is the diameter and Z ₁ is 1.2
mm to 2.1 mm, Z ₂ is 2.0 mm to 4.8 mm, Z ₃ is less than 8 mm, and variables r _i , p _i , ε _i , η _i and Z _i (i = 1). The specific values assigned to 2 and 3) are selected to provide the patient with the desired refraction and presbyopia correction). 42. The optical according to claim 41, wherein p ₁ = p ₃ = 1, η ₁ = η ₃ = 0 and, for i = 2, η ₂ = 0 by appropriate choice of other variables. surface. 43. The point on the optical surface is further defined by the following equation: (In the formula, x ₁ is a sagittal distance at the boundary between the first viewing area and the second viewing area, and x ₃ is a boundary between the second viewing area and the third viewing area. Is the sagittal distance at, y ₁ and y ₃ are the half chord diameters at these same boundaries, and y ₁ ′ and y ₃ ′ are tangents to the cross-sectional surface profile at these same boundaries). 43. The method of claim 42, wherein 44. A method of correcting presbyopia, comprising: a corneal surface comprising a first viewing zone, a second viewing zone surrounding the first zone and a third viewing zone surrounding the second viewing zone. A viewing zone, wherein the first viewing zone has a substantially single refractive power, the second viewing zone has a range of refractive powers, and the third viewing zone is the third viewing zone. A second substantially single power different from one single power,
Reshaping to include the first, second and third viewing zones, wherein at least one of the first, second and third viewing zones has an aspherical surface and the other zone has a spherical surface. And the point on the optical surface is represented by the following equation: Where x is the sagittal distance of a point on the surface, y is the half chord diameter,
Z ₁ is the chord diameter of the central first viewing zone, Z ₂ is the chord diameter (outer diameter) of the second viewing zone, and Z ₃ is the chord diameter of the third viewing zone. Is the diameter and Z ₁ is 1.2
mm to 2.1 mm, Z ₂ is 2.0 mm to 4.8 mm, Z ₃ is less than 8 mm and the variables r _i , p _i , ε _i , η _i and Z _i (i = 1). The specific values assigned to 2 and 3) are selected to provide the patient with the desired refraction and presbyopia correction). 45. The method according to claim 44, wherein p ₁ = p ₃ = 1, η ₁ = η ₃ = 0, and when i = 2, η ₂ = 0 by appropriate choice of other variables. . 46. The point on the optical surface is further defined by the following equation: (In the formula, x ₁ is a sagittal distance at the boundary between the first viewing area and the second viewing area, and x ₃ is a boundary between the second viewing area and the third viewing area. Is the sagittal distance at, y ₁ and y ₃ are the half chord diameters at these same boundaries, and y ₁ ′ and y ₃ ′ are tangents to the cross-sectional surface profile at these same boundaries). 45. The method of claim 44, wherein 47. The method of claim 44, wherein the reshaping surface of the cornea is the anterior or underlying surface formed by ablation or collagen contraction. 48. The ablation is performed by applying excimer laser, surgical laser, water cutting, fluid cutting, liquid cutting or gas cutting techniques.
The method described. 49. The method of claim 44, wherein the reshaping surface of the cornea is an artificial layer formed by placing a contact lens on the cornea. 50. The method of claim 44, wherein the reshaping surface of the cornea is the underlying surface formed by embedding the lens in the cornea. 51. A method of pre-adapting a patient to a final presbyopia correction prior to corneal reshaping, the method comprising: a first viewing zone spanning a central zone of the pupil, a second zone surrounding the first zone. A third viewing zone surrounding the second viewing zone and the first viewing zone having a first substantially single refractive power for near vision correction, The second viewing zone has a range of powers and the third viewing zone has a second substantially single power that is different than the first single power; The second refractive power is for distance vision correction, the first and third viewing zones have a spherical surface, and the second zone has an aspherical surface. To provide the patient with a pair of contact lenses, each containing a field of vision, and to contact the patient for only a short period of time to accommodate corrective vision The method comprising causing a worn lens, and reshape the cornea, and achieving optical surfaces to provide a power correction profile which corresponds to the refractive power of providing contact lenses satisfactory vision correction for the patient. 52. In contact lenses separate for the dominant and non-dominant eyes of a patient, stepwise as necessary to achieve presbyopia correction that is satisfactory to the patient at near, far and intermediate distances. 52. The method of claim 51, further comprising: providing a replacement contact lens having an adjusted first or second power correction or different Z ₁ or Z ₂ dimensions or combinations thereof. 53. The method of claim 51, wherein the cornea of the dominant eye is reformed to provide a downward correction for near vision in the first area. 54. The method of claim 51, wherein the cornea of the non-dominant eye is reshaped to provide downward correction for distance vision in the third area. 55. The method of claim 51, wherein the patient is provided with the replacement contact lens for at least one week. 56. The method of claim 51, wherein the patient wears the contact lens for at least one week. 57. A method of selecting a patient that is a desirable candidate for corneal engraving for correcting presbyopia, the method comprising: a first viewing zone spanning a central zone of a pupil, a second zone surrounding the first zone. A third viewing zone surrounding the viewing zone and the second viewing zone, the first viewing zone having a first substantially single refractive power for near vision correction; The second viewing zone has a range of powers, the third viewing zone has a second substantially single power that is different from the first single power, and The second refractive power is for distance vision correction, the first and third viewing zones have a spherical surface, and the second zone has an aspherical surface. Providing the patient with a pair of contact lenses, each containing a visual zone, and for a short period of time trying to adapt to corrected vision A patient who wears the contact lens by using the contact lens, and a patient who achieves a satisfactory vision correction at a short distance, a long distance, and an intermediate distance. Selecting as a candidate for undergoing corneal reshaping to obtain an optical surface that provides a correction profile. 58. In separate contact lenses for the dominant and non-dominant eyes of the patient, optionally in an attempt to achieve presbyopia correction that is satisfactory to the patient at near, far and intermediate distances. 58. further comprising providing a replacement contact lens having an adjusted first or second power correction or different Z ₁ or Z ₂ dimensions or combinations thereof.
The method described. 59. An ophthalmic surgical system for profiling the cornea to provide the eye with multifocal capability for correcting presbyopia, the system operable to deliver ablative laser radiation to the cornea. A laser capable of selectively exposing a portion of the cornea to the ablative radiation to provide a first viewing area on the cornea, a second viewing area on the cornea surrounding the first area, and the second viewing area on the cornea. A third viewing zone on the cornea surrounding the viewing zone of, the first viewing zone having a substantially single refractive power and the second viewing zone having a range of refractive powers. Of the first, second and third viewing zones, the third viewing zone having a second substantially single power different from the first single power. Said first, second and third viewing zones, at least one having an aspherical surface and the other two zones having a spherical surface System comprising a laser control system for creation. 60. The system of claim 59, wherein the first viewing zone has near vision correction power and the third viewing zone has far vision correction power. 61. The system of claim 60, wherein the first viewing zone covers a central zone of the pupil. 62. The system of claim 61, wherein the first and third viewing zones are spherical and the second zone is aspherical. 63. The second visual zone is an annulus concentric with the first visual zone, and the second visual zone has an inner diameter of 1.2 mm to 2.1 mm and a diameter of 2.0 mm.
63. The system of claim 62 having an outer diameter of 4.8 mm. 64. The second visual zone has an inner diameter of 1.5 mm to 1.9 mm and 2
． 64. The system of claim 63, having an outer diameter of 3 mm to 3.0 mm. 65. The system of claim 61, wherein the second viewing zone is adjacent to the first and third viewing zones. 66. The second viewing zone from the first single refractive power adjacent to the first viewing zone to the second single refractive power adjacent to the third viewing zone. 66. The system of claim 65, having a range of refractive power that continuously and substantially monotonically varies up to. 67. The first viewing zone surface has a first tangent that is adjacent to the second viewing zone surface, and the second viewing zone that is adjacent to the first viewing zone is the same tangent. 67. The system of claim 66, comprising: 68. The third viewing zone surface has a second tangent that is adjacent to the second viewing zone surface, and the second viewing zone that is adjacent to the third viewing zone has the same tangent. 67. The system of claim 66, comprising: 69. The system of claim 66, wherein the surfaces of the first, second and third viewing zones have a constant unidirectional concave shape. 70. The system of claim 61, wherein the first viewing zone covers less than 50% of the pupil area at ambient lighting conditions indoors. 71. The system of claim 61, wherein the first viewing area covers less than 38% of the pupil area at ambient lighting conditions indoors. 72. The computer selectively ablates a portion of the cornea to obtain the following equation: Where x is the sagittal distance of a point on the surface, y is the half chord diameter,
Z ₁ is the chord diameter of the central first viewing zone, Z ₂ is the chord diameter (outer diameter) of the second viewing zone, and Z ₃ is the chord diameter of the third viewing zone. Is the diameter and Z ₁ is 1.2
mm to 2.1 mm, Z ₂ is 2.0 mm to 4.8 mm, Z ₃ is less than 8 mm, and variables r _i , p _i , ε _i , η _i and Z _i (i = 1). 59. The specific values assigned to 2) and 3) are programmed to create an optical surface defined by) selected to provide the desired refraction and presbyopia correction to the patient.
The system described. 73. The optical surface is further defined by η ₂ = 0 by p ₁ = p ₃ = 1 and η ₁ = η ₃ = 0 and, if i = 2, by appropriate selection of other variables. 73. The system of claim 72. 74. The point on the optical surface is further defined by the following equation: (In the formula, x ₁ is a sagittal distance at the boundary between the first viewing area and the second viewing area, and x ₃ is a boundary between the second viewing area and the third viewing area. Is the sagittal distance at, y ₁ and y ₃ are the half chord diameters at these same boundaries, and y ₁ ′ and y ₃ ′ are tangents to the cross-sectional surface profile at these same boundaries). 74. The system according to claim 73. 75. The system of claim 59, wherein the desired refraction and presbyopia correction is pre-determined by a patient's subjective adaptation to a contact lens having a corresponding refraction and presbyopia correction. 76. A laser assembly for projecting radiation onto a selected area of an exposed surface of the cornea to ablate the selected area to a certain depth, and controlling the amount of radiation projected onto the area. To control the depth of corneal ablation to provide a first viewing zone, a second viewing zone surrounding the first zone and a third viewing zone surrounding the second viewing zone. And the first viewing zone has a substantially single refractive power, the second viewing zone has a range of refractive powers, and the third viewing zone has a first single viewing zone. A second substantially single power different from that of at least one of the first, second and third viewing zones has an aspherical surface and the other two zones have a spherical surface. A laser system controller for creating the first, second and third viewing zones. 77. A photorefractive corneal ablation system for correcting presbyopia of a patient's cornea, comprising a radiation source for emitting a laser beam of ablative radiation, receiving the beam and at least a portion of the beam. Beam shaping means for selectively transmitting to the cornea, and applying the beam to the cornea to remove a selected amount of corneal tissue from the region of the optical zone of the cornea by the ablative radiation, thereby, A first viewing zone, a second viewing zone surrounding the first viewing zone and a third viewing zone surrounding the second viewing zone, the first viewing zone being substantially single Second refraction power having a range of refraction powers, and the third refraction power is different from the first single refraction power. Having a refractive power of at least one of the first, second and third viewing zones A laser control system for forming a reprofiled region having the first, second and third viewing zones, one having an aspherical surface and the other two zones having a spherical surface. Refractive Keratectomy System.