WO2004023189A1

WO2004023189A1 - Presbyopia-correcting lens and method for the production of such a lens

Info

Publication number: WO2004023189A1
Application number: PCT/EP2003/008788
Authority: WO
Inventors: Kristian Hohla; Birte Jansen; Gerhard Youssefi
Original assignee: Technovision GmbH Gesellschaft für die Entwicklung medizinischer Technologie
Priority date: 2002-09-05
Filing date: 2003-08-07
Publication date: 2004-03-18
Also published as: WO2004023189A8; DE10241208B4; WO2004023189B1; DE10241208A1; AU2003260387A1

Abstract

The invention relates to a presbyopia-correcting lens, particularly a contact lens or intraocular lens, and a method for producing such a lens. At least one near vision zone having high refractive power and at least one far vision zone having low refractive power are arranged on said lens so as to provide simultaneous near vision and far vision. Said near vision and far vision zones merge by means of a transition area. The inventive lens is characterized by the fact that the at least one near vision zone and the at least one far vision zone are arranged in a rotationally asymmetric manner on the lens while the transition area is about centrally located on the lens and the distribution of the refractive power is approximately coma-shaped. The inventive production method allows client-specific lenses to be produced with a similar distribution of the near vision and far vision zones, the transition area being centered approximately in front of the pupil (optical axis) of the eye.

Description

Presbyopia correcting lens and manufacturing method for such a lens

The present invention relates to a presbyopia-correcting lens according to the preamble of claim 1 and to a manufacturing method for a presbyopia-correcting lens. Contact lenses or intraocular lenses (IOL's) can be used as lenses for the correction of presbyopia. If for the sake of simplicity only "contact lenses" are mentioned below, intraocular lenses are also always included.

With increasing age, the lens of every person loses its elasticity, so that the affected people can no longer see clearly in the vicinity. This deteriorating ability of the eye to adapt is called presbyopia or presbyopia.

To treat presbyopia, people can get a contact lens. On the one hand, these contact lenses correct the spherical and possibly cylindrical ametropia of the eye. On the other hand, in conjunction with the optical elements of the eye (cornea and eye lens), they generate a number of different focal points, i.e. they are bi- or multifocal.

Presbyopia-correcting contact lenses have at least one near-vision and one far-vision zone and can be divided into two categories according to their principle of action: simultaneous or alternating contact lenses. In the case of simultaneous presbyopia-correcting contact lenses, the near and far vision zones are always in front of the pupil, while in alternating contact lenses there is always only one zone in front of the pupil. Both systems are based on the idea of focussing the incident light on the retina, the focal point of the retina, wherever possible. With alternating lenses, only a single focal point is formed in any position of the eye, which is as close as possible to the fovea centralis. In known simultaneous lenses, the focal points of the near and far vision zones are spatially one behind the other and centered on the fovea centralis. Refractive, simultaneous presbyopia-correcting contact lenses are therefore conventionally shaped in such a way that they have annular, concentric zones with different refractive powers. Zones for distance vision alternate with zones for near vision, as described in US Pat. No. 5,835,192. US Pat. No. 5,691,797 discloses that intermediate zones having a medium refractive power can be inserted between annular zones for distance vision and zones for close vision.

A generic presbyopia-correcting contact lens is known from DE 32 22 099. Its optical zone is divided into a near part and a far part, which have different peak powers, i.e. have different radii of curvature. The two areas merge into one another in a narrow, vertical transition zone.

A disadvantage of such structures is that images from the near area and images from the far area are focused on the same point on the retina of the eye. The images from close and far range overlap. Each picture represents a washed-out light background for the other picture. The viewer's brain must now filter out from the overall picture which parts come from the near area and which parts come from the far area. It is hardly avoidable that errors occur. The task for the brain is further complicated by changing lighting intensity in that the pupil of the viewer opens or closes and therefore different numbers of near and far vision zones of the contact lens contribute to the overall image on the retina. In particular, the percentage contribution of the local area changes in relation to the contribution of the long-range area in the overall picture. This can lead to difficulties when driving at night, for example, when the lighting is very bright and then very dim again.

In the case of diffractive, simultaneous contact lenses, diffraction on fine, ring-shaped structures on the contact lens is used in order to also produce several foci in succession. The problem of overlaying the images on the retina arises in the same way as with refractive simultaneous contact lenses. In addition, that When diffraction occurs, a large proportion of the light, approx. 20%, is lost in higher diffraction orders. As a result, the user's vision deteriorates, especially in poor lighting.

In the case of alternating contact lenses, the switch from distant to close vision takes place in that the contact lens wearer changes his viewing direction and thus looks through a different zone of the lens. Such a contact lens is disclosed in DE 32 19 585 A1. In the middle area of this contact lens there is always a far vision zone in which the refractive power is adjusted to distant objects. A near vision zone is arranged in a sector shape on the contact lens. The transition between the near vision zone and the far vision zone is as sharp as possible, ideally an edge, since only a single zone should always contribute to vision and a transition area would only unnecessarily increase the distance the eye has to switch between distant and near vision. As a rule, the near vision zone is at the bottom, since the view is usually lowered for close vision, for example when reading. An alternating contact lens avoids the mixing of the images, but is disadvantageous overall since it only allows close-up vision in a certain direction. If a nearby object to be viewed lies in a different direction or the contact lens rotates on the eye, the contact lens wearer can no longer focus on the object.

Both simultaneous and alternating presbyopia-correcting contact lenses consequently have problems with their users' eyesight.

An object of the present invention is to improve known contact lenses for correcting presbyopia with a view to increasing the eyesight of the user.

Another object of the present invention is to provide a manufacturing method for such contact lenses.

The first object is achieved by a contact lens with the features of claim 1. The second object is achieved by a manufacturing method with the features of claim 13. The presbyopia-correcting contact lens according to the invention combines the advantages of alternating contact lenses with those of simultaneous contact lenses by deviating from the conventional goal of focusing all light rays on the fovea centralis. Due to the rotationally asymmetrical arrangement of the at least one near vision zone and the at least one far vision zone, the respective focal points for near and far vision on the retina of the user's eye are spatially laterally separated from one another, while the images from the near and far areas arise simultaneously. This offers several decisive advantages: Firstly, it is a relief for the brain, which no longer has to separate the images from each other, so that confusing mixing of the images is avoided. On the other hand, the reduced mixing of the images leads to a decisive improvement in the viewer's visual acuity, ie his resolving power. Another important advantage is the essentially central arrangement of the transition area with respect to the optical axis of the contact lens. The area through which the user's eye will look most frequently lies around the optical axis of the contact lens. The central arrangement of the transition area therefore ensures that the eye detects both a part of the near vision zone and a part of the far vision zone at the same time.

It is advantageous if the respective portions of the near vision and far vision zones are essentially constant on fictitious circular areas with different, arbitrary radii around the center of the contact lens. It follows from this that the proportions of the near and far vision zones become almost independent of the degree of opening of the pupil, since the proportions are always the same. This in turn prevents the relative contributions of the distant and near vision image from changing when the illumination intensity changes due to an opening or closing of the pupil, which could confuse the user.

Such a division is expedient, in which the proportion of the near vision zone or near vision zones in the fictitious circular area is between 25 and 60%, more particularly between 40 and 55%. A special case would be that the proportions of the near vision zones and the far vision zones in at least one fictitious circular area are equal to each other. This would make the intensities of the near and far vision images on the retina roughly the same.

To correct the ametropia of a user's eye, the presbyopia-correcting contact lens can have an average spherical and / or cylindrical refractive power. The near and far vision zones with higher or lower refractive power are then superimposed on this average refractive power.

In a preferred embodiment, the contact lens according to the invention has exactly one near vision and one far vision zone. The viewer's brain on the retina only has to distinguish between a single near image and a single distant image, which further reduces confusion between the images.

Another advantageous variant of the contact lens is that the distribution of the local refractive powers of the contact lens minus an average spherical and / or cylindrical refractive power essentially corresponds to a coma. In optics, a certain aberration of spherical lenses is usually referred to in optics, in which points located to the side of the optical axis are imaged in the form of a comet tail, since the light rays emanating from the points are incident at an angle to the optical axis of the lens. The effect of the coma can be better described in terms of waves optically. In a wave-optical description, the wavefront consists of those points on which the light has the same phase. Wavefronts often have a very complicated structure. They can be described mathematically by breaking them down into orthogonal functions. An example of such a decomposition, with the help of which wave fronts for optical systems with circular openings can be described, is a decomposition into Zemike polynomials. These Zemike polynomials Z have the following structure:

Here θ is the azimuth angle in the plane of the opening with

I: x: I and p is the normalized radial distance from the center of the opening, ie x

The radial part of the Zernike polynomial is the so-called radial function:

n is referred to as the "order" of each term. The following applies: x n and I are always either both even or both are odd; all other terms are omitted. For I, depending on n:

For every possible combination of n and I, m results in

An example: For the third order, n = 3. The values -3, -1, 1 and 3 are then available for I. In the terms with n = 3 and 1 = 1, -1, m = 1. In the radial function R _n ', the index s therefore assumes the values s = 0 and s = 1.

The terms in the Zemike polynomial Z that result for these values have the following form:

These two terms (n = 3, 1 = 1, -1) are called third-order coma. The surface shapes described with these terms differ only by a 90 ° rotation in the azimuth direction. They are shown in a perspective view in FIG. 5. The two terms with n = 5 and 1 = 1, -1 (m = 2) are called fifth-order coma.

A coma-shaped distribution of the local refractive powers creates a near-vision and a far-vision zone that are exactly opposite in relation to the center of the contact lens. Investigations have shown that such a distribution of the refractive powers of the contact lens leads to particularly good vision, in particular particularly high vision. This applies both to a distribution of the local refractive powers according to a third-order coma and a distribution according to a fifth-order coma. By "essentially coma-shaped" it is meant that the distribution of the refractive powers need not exactly match the corresponding term in the Zemike polynomial. For example, it is possible that the distribution stretches in every radial direction or only in certain radial preferred directions compared to a mathematically exact coma or compressed, and it could be that the coma is under a side slope, called a tilt, which could result in the near vision portion being somewhat stronger than the distant vision portion or vice versa.

The refractive power difference between a zone of maximum and a zone of minimum local refractive power of the contact lens is preferably between 0.5 and 7 diopters. The strength chosen would depend on the degree of presbyopia of the user. For most users, a difference in refractive power between 0.7 and 5 diopters would be sufficient.

It is very useful if the presbyopia-correcting contact lens according to the invention has means for stabilizing the position of the eye, in particular for stabilizing the rotation. This ensures that the near and far images are always arranged in the same way on the retina, which makes it much easier for the user to see. Rotation stability can be achieved, for example, by weighting the lower edge of the contact lens or by flattening the lower and upper edges of the contact lens. The respective arrangement of the near and far vision zones in the stabilized position is largely irrelevant. For example, it would be possible for the zones to lie horizontally next to one another or vertically one above the other, but also a diagonal arrangement would be conceivable. The only thing that matters is that the arrangement once selected remains stable so that the viewer's brain can get used to the spatial separation of the images.

Using the manufacturing method according to the invention, presbyopia-correcting contact lenses can be produced which are adapted to the individual needs of the user. For this purpose, the measured aberrations of an eye are taken into account and thus the distribution of the local refractive properties of the eye. Before the production of the contact lens, the optical aberrations are preferably measured not of the eye alone but of an eye with the contact lens attached. In this way, it is taken into account which shape the contact lens takes on the eye and which aberrations result in the entire optical system. The contact lens is then manufactured or processed in such a way that the resulting entire optical system comprising the eye and the contact lens has at least one near vision zone and at least one far vision zone, which are arranged rotationally asymmetrically to the optical axis of the system. This takes into account in the manufacture of the user-specific contact lens that the transition area between the near vision and far vision zone does not necessarily have to be arranged centrally on the contact lens, but that it is important to arrange it centrally in front of the pupil of the user's eye. As stated above, this means that the respective portions of the near and far areas hardly change when the pupil is opened or closed.

In order to take into account the movement of the contact lens on the eye, it is advantageous to mathematically extrapolate the measured values of the optical aberrations of the eye beyond the measured area. This avoids edges on the contact lens that could impair vision. The edges of the near and far vision zones blend smoothly into the surrounding areas.

In a special embodiment, the contact lens is manufactured in such a way that, due to the arrangement of a near vision zone, a far vision zone and the transition area, a wavefront originating from a point on the retina of the eye essentially passes through a coma after passing through the eye and the contact lens. has. As stated above, users with such a wavefront achieve the best vision.

In addition, the position of the contact lens sitting on the eye can also be measured and taken into account during manufacture. The position data can include the horizontal and / or vertical decentering of the contact lens with respect to the pupil of the eye. In the case of cylindrical contact lenses, the position of the cylinder axis or, in the case of directionally stabilized, marked contact lenses, the position of the marking axis can also be measured.

In order to obtain particularly meaningful values, the position data can be measured over a plurality of measurement times and then a specific value can be calculated from the measured position data, which is then used as the basis for the manufacture of the contact lens. The calculated value can be, for example, the maximum of a frequency distribution of the measured values or an average of the measured values. It indicates a preferred position of the contact lens on the eye.

It is advisable to carry out a wavefront measurement to measure the optical aberrations of the eye or the eye contact lens system, for example by means of a Hartmann shack sensor. The higher aberrations can also be recorded with such a measurement. In addition, the shape of the contact lens to be produced can be calculated in a simple manner from the measured wavefront by determining the deviation of the measured wavefront from a target wavefront. Such a desired wavefront is preferably used, which itself has a coma.

One possibility for the production of the contact lens is that the contact lens put on and measured on the eye is reworked. This has the advantage that their behavior is well known to the user's eye. The method can be carried out in particular with hard contact lens materials. Another possibility is to first put a hydrated (or hydrated) soft contact lens on the eye to measure the optical aberrations of the eye and then to rework a contact lens blank that is the same as its manufacture, according to the measured data, before it is hydrated. This procedure offers enormous advantages for soft contact lens materials. To determine the behavior of the contact lens on the eye, the contact lens material must be hydrated. However, in the hydrated state, the material cannot be processed in a predictable manner, since the material properties can change due to a reduction in the water content during the finishing process. In order to avoid this disadvantage, a contact lens blank of the same manufacture is processed before it is hydrated, since in this state the processing can be carried out very precisely and predictably.

Various processing methods are available for producing the contact lens, for example casting methods, removal methods, compression methods or material deposition methods.

Particularly good results are achieved with a material removal process using laser radiation. Both UV lasers with a photoablative ablation process and ultrashort pulse lasers with a photodisruptive ablation process can be used.

Advantageous exemplary embodiments of the invention are illustrated below with the aid of a drawing. Show it:

FIG. 1 shows a plan view of a first exemplary embodiment of a presbyopia-correcting contact lens according to the invention,

FIG. 2 shows a plan view of a second exemplary embodiment of a presbyopia-correcting contact lens according to the invention,

FIG. 3 shows a top view of a third exemplary embodiment of a contact lens, which was produced by means of the production method according to the invention,

FIG. 4 shows a schematic view of an eye with a contact lens according to the invention,

FIG. 5 shows a perspective view of a height profile of a pure third-order coma and a sphere,

FIG. 6 shows a perspective view of a height profile which results from summation of the coma and sphere shown in FIG. 4, and

Figure 7 is a perspective view of a fourth embodiment of a presbyopia-correcting contact lens.

Identical parts are provided with the same reference symbols in all figures.

FIG. 1 shows a first exemplary embodiment of a presbyopia-correcting contact lens 1 according to the invention. The contact lens 1 is directionally stabilized in that it has flattened lower and upper carrying edges 2. Due to the blinking of the eyes, the carrying edges 2 of the contact lens 1 are oriented essentially upwards or downwards on the eye. The contact lens 1 can be formed from both hard and soft contact lens material. At the widest point of the lower support edge 2, a cross-shaped marking 3 is attached. An extended arm of the marking 3 is aligned with the center 4 of the contact lens 1. It thus indicates the position of a marking axis 5, which extends from the marking 3 to the center of the contact lens 4.

Between the carrier edges 2, an elliptical optical zone 6 remains on the circular contact lens 1, through which the wearer of the contact lens 1 can bite when the zone 6 is arranged in front of his pupil 7. The contact lens 1 is shaped such that the center 4 of the contact lens is usually directly above the center of the pupil 7 of the user. The optical zone 6 of the contact lens 1 has three hatched zones with different refractive powers: a near vision zone 8 with a relatively high refractive power, a far vision zone 9 with a lower refractive power and a transition region 10 in which the different refractive powers continuously merge. The local changes in the refractive power are caused by the respective inner and outer surface topography of the contact lens 1. Areas with a greater curvature have a higher refractive power than areas with a lower surface curvature. However, it would also be conceivable to achieve the changes in the refractive power with constant surface curvature by changes in the local material composition. For this purpose, the material of the contact lens could, for example, be locally doped so that zones with a higher refractive index and zones with a lower refractive index are formed.

In the individual zones 8, 9, 10, the respective refractive power is not necessarily constant. For example, the local refractive power can assume a maximum at a point of the near vision zone 8 and become lower towards the edge of the near vision zone 8. Accordingly, the local refractive power could assume a minimum at one point of the far vision zone 9 and increase towards the edge of the far vision zone 9. The most important thing is that the refractive powers of the near vision zone 8 and the far vision zone 9 smoothly merge into one another in the transition region 10 without an edge or without a jump in the refractive power.

The transition region 10 is arranged centrally on the contact lens 1, the center 4 of the contact lens 1, through which the optical axis of the contact lens 1 runs, is therefore in the transition region 10. In the horizontal direction, the width of the transition region 10 is only about 50 μm to 1 mm. preferably about 100 to 300 μm, so that even with strong illumination and thus narrowed pupil 7, both part of the near vision zone 8 and part of the far vision zone 9 lie in front of the pupil 7. Only in such a situation, in which the pupil 7 detects both a part of the near vision zone 8 and a part of the far vision zone 9, is it possible for the wearer of the contact lens 1 to have near and far vision at the same time. In interaction with the light-refractive properties of the eye of the contact lens wearer, two develop on the retina spatially adjacent images - one from the near range and one from the far range, since the arrangement of the near vision zone 8 and the far vision zone 9 on the contact lens 1 is rotationally asymmetrical. If the contact lens 1 is aligned on the eye in the manner shown in FIG. 1, the two images lie horizontally next to one another.

If the pupil 7 of the contact lens wearer opens when the lighting becomes weaker, the pupil 7 detects a larger, always circular area of the optical zone 6. Due to the shape of the near vision zone 8, the far vision zone 9 and the transition area 10, the respective portions of the near vision zone 8 remain and the remote viewing zone 9 are essentially constant. In the exemplary embodiment shown, starting from the center 4 of the contact lens 1, the respective portions of the near vision and far vision zones 8, 9 are almost identical to one another in circular areas around the center of the contact lens 4, regardless of the radius. Their respective share in the circular area around the contact lens center 4 is about 30%.

FIG. 2 shows a second exemplary embodiment of a contact lens 20 according to the invention. The contact lens 20 is also rotationally stabilized by flattened lower and upper carrying edges 2, between which it has an optical zone 6. In contrast to the first exemplary embodiment, the contact lens 20 has two near vision zones 21 and two distant vision zones 22, each of which takes approximately the shape of a circular quarter. The zones 21, 22 are arranged in such a way that the two near vision zones 21 are exactly opposite one another by 180 °, just as the two far vision zones 22 are offset from one another by 180 °. Centered to the center of the contact lens 4, there is a transition region 23 with a medium refractive power between the near vision and far vision zones 21, 22. Close and far vision zones 21, 22 lying next to one another also go soft in the circumferential direction, i.e. without a jump in refractive power, into each other.

As in the first exemplary embodiment, the extent of the transition region 23 on the contact lens 20 is so small that even with the pupil 7 closed relatively far, both near-vision zones 21 and distant-vision zones 22 are detected by the pupil 7. Furthermore, the zones 21, 22 are also shaped and arranged here in such a way that the respective proportions of the near vision zones 21 and distant vision zones over a relatively wide range. NEN 22 are independent of a radius starting from the center of the contact lens 4. Both the near vision zones 21 and the distant vision zones 22 have approximately a 30% share of circular areas around the contact lens center 4. Due to the sector-shaped arrangement of the near vision zones 21 and distant vision zones 22, the contact lens 20 creates four spatially separate images on the retina of the Contact lens wearer generated, of which two images come from close range and two images from far range.

FIG. 3 shows a third exemplary embodiment of a presbyopia-correcting contact lens 30 according to the invention. In contrast to the first two exemplary embodiments, the contact lens 30 has been adapted to a specific user by means of the production method according to the invention. The middle position is shown which the directionally stabilized contact lens 30 assumes due to the tear film, the eyelid tension and the shape of the surface of the contact lens wearer. In this middle position, the contact lens 30 is translationally decentered with respect to the pupil 7, specifically in the horizontal direction by Δx and in the vertical direction by Δy. Δx and Δy denote the deviation of the contact lens center 4 from the center 31 of the pupil 7. Furthermore, the marking axis 5 of the contact lens 30 no longer points vertically downward, but is at an angle to the vertical.

Like the first exemplary embodiment of a contact lens 1, the contact lens 30 also has a near vision zone 32 with a higher refractive power, a far vision zone 33 with a lower refractive power and in between a transition region 34 with a medium refractive power. In contrast to the first exemplary embodiment, the zones 32, 33, 34 in the contact lens 30 are no longer centered on the contact lens center 4, but instead on the pupil center 31. The mean decentering of the contact lens center 4 with respect to the pupil center 31 was taken into account, which was calculated, for example, by averaging over a large number of measuring times.

In this exemplary embodiment, the transition region 34 lies in front of the pupil center point 31. The near vision and far vision zones 32, 33 are arranged on the contact lens 30 in the measured mean position of the marking axis 5 shown in FIG. 3 such that they lie horizontally opposite one another. This middle axis position of the marking Approximation axis 5 can also be determined over a large number of measurement times and calculated by calculating an average value or as the maximum of a frequency distribution of the measurement values. It is the position that the contact lens 30 will most often occupy on the eye of the contact lens wearer. In this position, two horizontally spatially separated images are generated on the user's retina.

An eye 35 is drawn schematically in horizontal section in FIG. 4. Its cornea is designated 36, the retina 37. The optical axis 38 of the eye is the straight line that runs through the center 31 of the pupil 7. The illustration in Fig. 4 is not to scale. In particular, a contact lens 30 according to the invention, which is placed on the eye 35, is shown enlarged. It is in a position-stabilized preferred position on the eye 35. In this preferred position, the center of the contact lens 4 is not on the optical axis 38 of the eye, but laterally offset from it. However, the optical axis of the entire eye-contact lens system is defined by the optical axis 38 of the eye. For this reason, in the case of the contact lens 30, the near and far vision zones 32, 33 are not centered on the center of the contact lens 4, but rather on the optical axis 38 of the entire eye / contact lens system.

FIG. 5 shows a perspective representation of the height profile of a surface shape which results from a pure third-order coma. As stated above, this is the term in a Zernike polynomial that arises from the coefficients n = 3 and 1 = 1, -1 and therefore has the following form:

The circular coma 40 has a depression 41 on one side and an elevation 42 on the other side. A radial axis 43 has the same height as the edge of the coma 40.

Below the coma 40 is shown a convex, spherical surface 44 which has the same radial extent R as the coma 40. The height profile 50 shown in FIG. 6 is created by adding the two height profiles shown in FIG. 5, ie the coma 40 and the spherical surface 44. The center 51 of the height profile 50 has the same height as the center of the spherical surface 44, since the coma 40 is on nothing contributes to this point. In the left area, the curvatures of the spherical surface 44 and the depression 41 of the coma 40 just cancel each other out, so that a flat zone 52 is created in this area. On the right hand side, however, a raised area 53 is created by adding the elevation 42 of the coma 40 to the spherical surface 44. This raised area 53 has a flank 54 that slopes steeply toward the edge of the height profile 50.

The height profile 50 represents a highly exaggerated profile that can be used in a presbyopia-correcting contact lens 1, 30 according to the invention. The refractive power of the spherical surface 44 is selected such that it corrects the mean spherical ametropia of the contact lens wearer. The spherical correction can in particular also be zero if the user of the contact lens 1, 30 has no spherical ametropia. In this case, the curvature of the spherical surface 44 would correspond approximately to the curvature of the cornea 36 of the contact lens wearer.

In the raised area 53 there is the strongest surface curvature of the profile 50, and thus also the strongest refractive power. This area therefore represents the near vision zone 8, 32. The weakest curvature, however, is in the largely flat area 52, so that this area forms the far vision zone 9, 33. The near vision and far vision zones merge smoothly into one another via the center 51 of the height profile 50, so that the transition region 10, 34 lies at the center 51.

The radial extent R of the height profile 50 depends on an average pupil radius and is therefore, for example, between 1.5 and 4 mm. The vertical extent V between the edge of the profile 50 and the tip of the raised area 53, on the other hand, is shown as greatly increased. In the case of a real contact lens 1, 20, 30, the vertical dimension V would be in the range of a few micrometers, for example between 5 and 100 micrometers. A contact lens can be provided with a height profile 50 by first selecting a spherical contact lens whose original surface 55, shown in broken lines, is curved so strongly that it coincides with the steepest flank 54 of the profile 50. Starting from the surface 55, the surface profile 50 can then be obtained by material removal, for example by means of a laser. For this purpose, more material has to be removed in the area 52 than in the area 53. The difference between the original surface 55 and the profile 50 is the removal profile 56. For a user-specific contact lens 30, the center 51 of the height profile 50 would be placed in such a way that it coincides as closely as possible with the user's pupil center 31, since the optical axis 38 of the eye-contact lens system runs through it.

As an alternative to removing material from a surface profile 55, it would be possible to use a contact lens blank which has not yet been hydrated and which would have a surface 55 only in the hydrated state. Material could then be removed from this contact lens blank in such a way that the reworked contact lens blank would have the surface shape 50 after it had been hydrated. In the case of soft contact lens materials, this procedure offers enormous advantages with regard to the predictability of the processing result.

So far, the height profile 50 shown in FIG. 6 has been described as a real, albeit excessive, surface profile of a contact lens 1, 20, 30. In an abstract way, however, it could also be understood as a representation of the local refractive power profile of a presbyopia-correcting contact lens according to the invention. It indicates that the greatest refractive power is present in area 53 and the lowest refractive power in area 52. Such an approach is appropriate if the differences in the local refractive powers are not achieved by changing the height profile, but rather by varying the local refractive indices by using a material with a higher refractive index in region 53 and a material with a lower refractive index in region 52.

FIG. 7 shows a perspective view of a fourth exemplary embodiment of a contact lens 60 according to the invention. The contact lens 60 has an annular spherical see edge area 61. A small shoulder 62 indicates where the inner optical zone 6 of contact lens 60 is located. The surface profile 63 of the contact lens 60 in the optical zone 6 is similar to the profile 50 shown in FIG. 6 and is shown exaggerated in relation to the edge region 61. It is formed by adding the profile 50 to a spherical contact lens and smoothing the transitions at the edge of the profile 50. The resulting profile 63 is therefore based on a central sphere 64 with a greater curvature than in the situation shown in FIGS. 5 and 6. A coma 40 is added to this middle sphere 64, which defines the mean spherical refractive power of the contact lens 60. In the area 65, the profile 63 is therefore lower than the sphere 64, while in the area 66 it has an increase compared to the middle sphere 64. The distant vision zone of the contact lens 60 lies in the region 65, while its near vision zone lies in the region 66. The transition region 67 is centered at the center of the contact lens 4.

For a user whose eye 35 has at most a spherical ametropia, the contact lens 60 has the effect that a wavefront originating from a point on the retina 37 of the user eye 35 essentially has a coma 40 after passing through the eye 35 and the contact lens 60 having. The part of the wavefront that emerges from the region 66 is retarded due to the passage through a thicker material layer, while the part of the wavefront emerging from the region 65 is advanced. The shape of the wavefront emerging from the eye contact lens system 35, 60 can be determined by means of a wavefront measurement, for example by means of a Hartmann shack sensor. Such a wavefront, which only deviates from a flat wavefront in the form of a coma 40, is ideal for correcting presbyopia, since it provides the user with particularly good vision.

In addition to spherical ametropia, most users also have cylindrical or higher aberrations. In order to generate the ideal wavefront just described, the aberrations of the user eye 35 must be eliminated by means of a user-specific contact lens 30, 60 such that only a coma (third or fifth order) remains. For this purpose, the aberrations of the eye 35 are first measured, preferably using a spherical or cylindrical contact lens. From the measured wavefront or from it calculated aberrations is then calculated how a refractive power profile of a contact lens must look in order to generate an ideal wavefront with this refractive power profile in conjunction with the aberrations of the eye 35. The refractive power profile can also be represented as a height profile 50, 63. By deducting the calculated height profile 50, 63 from an initial profile 55 of a contact lens, an ablation profile 56 is determined which takes into account the aberrations of the user eye 35.

The present invention can be generalized to the effect that at least one near-vision zone and at least one far-vision zone are created for the correction of presbyopia for the presbyobe eye 35, which zones merge into one another through a transition area arranged approximately centrally in front of the optical axis 38 of the eye 35, the arrangement the at least one near vision zone and the at least one far vision zone in front of the eye 35 is rotationally asymmetrical. This can be achieved not only with a contact lens, but also with glasses, for example. The transition area would lie on the spectacle lens approximately at the point through which the eye 35 looks most frequently. Close-up and far-vision zones are arranged so close to the transition area that they enable the eye 35 to simultaneously see near and far. The two spectacle lenses would preferably have the same spatial distribution of the local refractive powers, so that the images generated on the reticles 37 of the two eyes 35 are approximately identical to one another. As an alternative to contact lenses or glasses, intraocular lenses could also be provided with the refractive power distribution according to the invention. The term “contact lens” in the present description is therefore also understood to mean intraocular lenses.

Another possibility would be to deform the cornea of the presbyopic eye 35 directly in such a way that a rotationally asymmetrical distribution of near and far vision zones occurs in front of the pupil of the eye 35. With such a procedure, the transition area could be arranged exactly in front of the pupil center 31. It would have to be so small that even with a largely closed pupil 7, both near vision and far vision zones contribute to vision. Here, too, the distribution of the local refractive powers would essentially correspond essentially to a coma 40. An advantage of such direct processing of the cornea surface is that the wavefront generated by means of the cornea surface topography is exactly the same in every viewing direction, since it cannot change due to a shift of a contact lens in front of the cornea 36. For this reason, the spatial distribution of the close-up and form images on the retina 37 is always constant, which makes it much easier for the viewer's brain to get used to it. It is no longer necessary to distinguish between a state with a contact lens attached and a state without a contact lens attached. Another advantage, particularly for sensitive patients, is that they no longer have to wear a contact lens that irritates the cornea.

Well-developed procedures are now available for refractive surgery on the cornea 36, for example the conventional LASIK (laser in situ keratomileusis), or the more recent femtosecond LASIK, in which the stroma of the cornea is first “perforated” as desired using a femtosecond laser and after the front surface of the cornea is opened, a lenticle produced by the perforation is removed.

Claims

Expectations

1. Presbyopia-correcting lens (1, 20, 30, 60), in particular contact lens or intra-ocular lens, with at least one near vision zone (8, 21, 32, 66) with high refractive power and at least one far vision zone (9, 22, 33, 65) with lower refractive power for simultaneous near and far vision, the refractive powers of the near vision and far vision zones continuously merging into one another in a transition region (10, 23, 34, 67) arranged approximately centrally to the optical axis (4) of the lens, and the Arrangement of the at least one near vision zone (8, 21, 32, 66) and the at least one far vision zone (9, 22, 33, 65) on the lens is rotationally asymmetrical, characterized in that the distribution of the local refractive powers of the lens (1, 20, 30, 60) minus an average spherical and / or cylindrical refractive power essentially corresponds to a coma (40).

2. Presbyopia correcting lens according to claim 1, characterized in that on fictitious circular areas with any radii around the center (4) of the lens (1, 20, 30, 60), the respective proportions of the near vision (8, 21, 32, 66 ) and far vision zones (9, 22, 33, 65) are essentially constant.

3. Presbyopia correcting lens according to claim 2, characterized in that the proportion of near vision zones (8, 21, 32, 66) in the fictitious circular area is between 25 and 60%.

4. Presbyopia correcting lens according to claim 3, characterized in that the proportion of the near vision zone (8, 21, 32, 66) in the fictitious circular area is between 40 and 55%.

5. Presbyopia correcting lens according to at least one of the preceding claims, characterized in that the proportions of the near vision zones (8, 21, 32, 66) and the distant vision zones (9, 22, 33, 65) are the same in at least one fictitious circular area.

6. Presbyopia-correcting lens according to at least one of the preceding claims, characterized in that it has a medium spherical and / or cylindrical refractive power.

7. Presbyopia correcting lens according to at least one of the preceding claims, characterized in that it has exactly one near vision (8, 32, 66) and one far vision zone (9, 33, 65).

8. Presbyopia-correcting lens according to at least one of the preceding claims, characterized in that the coma-shaped distribution of the local refractive powers essentially corresponds to a coma (40) of the third order (n = 3, 1 = 1, -1).

9. Presbyopia-correcting lens according to at least one of claims 1 to 7, characterized in that the coma-shaped distribution of the local refractive powers corresponds essentially to a fifth-order coma (n = 5, I = 1, -1).

10. Presbyopia correcting lens according to at least one of the preceding claims, characterized in that the refractive power difference between a zone of maximum (53, 66) and a zone of minimum (52, 65) local refractive power of the lens is 0.5 to 7 diopters.

11. Presbyopia correcting lens according to at least one of the preceding claims, characterized in that the refractive power difference between a zone of maximum and a zone of minimum local refractive power of the lens is 0.7 to 5 diopters.

12. Presbyopia-correcting lens according to at least one of the preceding claims, characterized in that it has means (2) for position stabilization, in particular for rotation stabilization.

13. Manufacturing method for a presbyopia-correcting lens (30, 60) according to measured aberrations of an eye (35) or an eye-lens system, wherein at least one near vision zone (32, 66) and at least one far vision zone (33, 65) of the eye-lens system are rotationally asymmetrical to an optical axis (38) of the system, characterized in that a near-vision zone (32, 66), a far-vision zone (33, 65) and a transition area (34, 67) on the lens (30, 60) can be arranged in such a way that a wave front emanating from a point on the retina (37) of the eye (35) essentially passes through a coma (40 after passing through the eye (35) and the lens (30, 60) ) having.

14. The production method according to claim 13, characterized in that a transition region (34, 67) between the near vision and far vision zone is arranged approximately centrally to the optical axis (38) of the eye-lens system.

15. Manufacturing method according to one of claims 13 to 14, characterized in that before the manufacture of the lens (30, 60) the measurement of the optical aberrations of the eye (35) is carried out with a lens sitting on the eye.

16. The production method according to at least claim 15, characterized in that the measured values of the optical aberrations of the eye (35) are extrapolated beyond the measured range.

17. The production method according to at least one of claims 13 to 16, characterized in that the position data of the lens seated on the eye (35) are measured before the lens (30, 60) is manufactured.

18. The production method according to at least claim 17, characterized in that the measured position data comprise the horizontal and / or vertical decentration (Δx, Δy) of the lens with respect to the pupil (7) of the eye (35).

19. Manufacturing method according to at least one of claims 17 or 18, characterized in that the measured position data comprise the cylinder axis position or marking axis position (5) of the direction-stabilized lens.

20. Manufacturing method according to at least one of claims 17 to 19, characterized in that the measurement of the position data over a plurality of measurement Points in time occur and a value of a preferred position of the lens (30, 60) on the eye (35) is calculated from the measured position data and is taken into account when manufacturing the lens (30, 60).

21. The production method according to at least claim 20, characterized in that the calculated value is a maximum of a frequency distribution or an average of the measured values.

22. The production method according to at least one of claims 13 to 21, characterized in that a wavefront measurement is carried out to measure the optical aberrations of the eye (35) or of the eye-lens system.

23. The production method according to at least one of claims 13 to 22, characterized in that the shape (50, 63) of the lens (30, 60) to be produced is calculated from the deviation of the measured wavefront from a desired wavefront having a coma (40) ,

24. Manufacturing method according to at least one of claims 13 to 23, characterized in that the lens (30, 60) is produced by the lens which is placed on the eye (35) being reworked.

25. The production method according to at least one of claims 13 to 23, characterized in that the lens (30, 60) is produced by a hydrated, soft lens is placed on the eye for measuring the optical aberrations of the eye (35) and then a the same-manufactured lens blank is reworked according to the measured data before it is hydrated.

26. The manufacturing method according to at least one of claims 13 to 25, characterized in that a casting method, removal method, compression method or material deposition method is used to produce the lens (30, 60).

27. Manufacturing method according to at least claim 26, characterized in that the material removal process is carried out by means of laser radiation.