HK1169303B - System for forming and modifying lenses and lenses formed thereby - Google Patents

Description

System for forming and modifying lenses and lenses formed thereby

Cross-referencing

This application claims the benefit of the following U.S. provisional applications: 61/209,362 filed on 3/4/2009, 61/209,363 filed on 3/4/2009, 61/181,420 filed on 5/27/2009, 61/181,519 filed on 5/27/2009, and 61/181,525 filed on 5/27/2009. These U.S. provisional applications are incorporated herein by reference. In the event that the following description is inconsistent with the disclosures of these provisional applications, the following description shall control.

Technical Field

The present invention relates to a system and lens, and more particularly to a system for forming and modifying a lens and a lens formed by the system.

Background

The lens is implanted in the eye to improve vision. Generally, there are two types of intraocular lenses (intraocular lenses). One type of intraocular lens replaces the natural lens of the eye, often replacing the cataractous lens. The other type is used to supplement existing lenses and as permanent corrective lenses. A replacement lens is implanted in the posterior chamber. Supplemental lenses, known as phakic IOLs (intraocular lenses), are implanted in the anterior or posterior chamber to correct refractive errors of the eye.

There are two common techniques for forming intraocular lenses. One technique is molding (molding), in which an optically polymeric material is formed into a desired shape having a predetermined optical power. These lenses are available in standard refractive power, typically differing by about 0.5 power. The problem with the molding technique is that it is very expensive to manufacture customized lenses and therefore, for most patients, only an approximate way to obtain clear vision is available. For some patients, the refractive power may have an error of 0.25 or more. In addition, these lenses are generally less effective for patients with abnormally shaped corneas, including some patients who have undergone corneal surgery, such as LASIK surgery.

Another technique used is ablation (lathing) and milling (milling), in which a disc-shaped lens blank is ground to the desired shape. Due to the nature of the materials used for intraocular lenses, it is preferred to machine the lenses at reduced temperatures, such as-10 ° F. The problem with ablation and abrasion is that the optical properties of the lens at-10 ° F may differ from those of the lens at body temperature, so that such lenses only approach optimal vision. Furthermore, as the lens warms, it absorbs moisture and the size of the lens may change, thereby changing the refractive power of the lens.

For some patients, it is desirable that the lens be aspherical to correct corneal spherical aberration, or toric to correct or reduce corneal astigmatism over a range of powers. Commercially available IOLs typically do not uniformly correct these optical defects because this requires the inventory (inventoryy) of hundreds, if not thousands, of different types of lenses, all of which differ in refractive power, aspheric, and toric characteristics.

Another problem associated with conventional manufacturing techniques is that the lens is generally not able to accommodate the needs of a patient who has undergone LASIK (laser assisted in situ keratomileusis) surgery. LASIK surgery can correct myopia, hyperopia, and/or astigmatism. However, the replacement of the cornea produced in LASIK surgery makes it difficult to find an IOL with the proper accommodation for aspheric surfaces. Conventional IOLs are generally unsatisfactory for patients who have undergone LASIK surgery or have an abnormal cornea because of the challenges of inventorying IOLs suitable for such patients.

Techniques for improving the refractive index of an optical polymeric material, such as in an IOL, are discussed in U.S. publication 2008/0001320 to Knox et al. This technique uses a laser to change the refractive index of a small area of optical material, resulting in a change in refractive index of up to about 0.06, which is insufficient for most applications to change the optical power.

Accordingly, there is a need for a system for forming an intraocular lens that overcomes the shortcomings of the prior art manufacturing techniques and that also enables customization of the lens to provide a variety of corrective characteristics to approximate optimal vision, including for patients who have undergone LASIK surgery.

Disclosure of Invention

The present invention provides a system that satisfies this need, and also provides lenses formed and modified by the system. Lenses formed from this system have unique properties. The lens is typically an IOL, but the invention has other applications as described below. The lens according to the invention comprises a body formed of an optical material having a refractive index. The body has opposing inner and rear surfaces and an optical axis. The body contains modified loci (modified loci). The modification track has been formed by a laser beam and has a different refractive index than the material before modification. The lens has a number of unique features and is characterized by at least one, all, or any combination of the following features:

(i) sufficient modified loci in the body such that the refractive index of the body has been modified sufficiently to change the optical power of the body by at least plus or minus 0.5 (i.e., a positive optical power change of at least 0.5 or a negative optical power change of-0.5 or more, e.g., -10);

(ii) at least some of the modified tracks have an optical path length of 0.1 to about 1 wave greater than the optical path length of the unmodified tracks, wherein the wavelength is with respect to light of a wavelength of 555 nm;

(iii) at least some of the modified trajectories are in a substantially circular pattern (pattern) around the optical axis;

(iv) sufficient modification trajectories such that at least 90% of light projected onto the front surface in a direction substantially parallel to the optical axis passes through the at least one modification trajectory;

(v) at least some of the modified tracks are right cylindrical in shape with an axis substantially parallel to the optical axis and a height of at least 5 μm;

(vi) the rear surface and the front surface are both substantially planar; and

(viii) each modified track has a depth of 5-50 μm.

Typically, at least 1,000,000 or more modified tracks are located in a first layer of the body, the first layer being substantially parallel to the front surface, wherein the layer is about 50 μm thick. A modified track of a circular pattern, called an annular ring pattern, may be used.

When modified trajectories are used to achieve the desired optical effect, and more conventional configurations are not used, there are preferably sufficient trajectories for at least 99% of the light projected onto the front surface of the body in a direction substantially parallel to the optical axis to pass through the at least one modified trajectory. Thus, substantially all of the optical effect provided by the lens may be provided by modifying the trajectory.

The lens may provide optical power adjustment and may also be used to provide toric and/or aspheric adjustment.

An advantage of the present invention is that the lens body can be made very thin, in order from a maximum thickness of about 50 to about 400 μm, which in the case of an intraocular lens can be easily inserted into the posterior chamber of the eye. This allows the surgeon to make a smaller incision in the eye than would be possible with a conventional intraocular lens. Preferably, the maximum thickness of the body is about 250 μm.

In the present invention, the anterior and posterior surfaces are substantially planar, which has the advantage that there are no features on the body that interfere with the placement of the IOL in the posterior chamber of the eye.

Typically, the modified track has a depth of about 5 to about 50 μm. Each modification trajectory may have 1-10 sites, each site typically formed by a sequence of about 100 infrared laser pulses focused in a single burst (burst) onto a single point, site. At least some of the modified tracks may be adjacent to each other.

The modified track may have multiple layers, where each layer may have a thickness of about 50 μm. Typically, the multiple layers are spaced apart from each other by about 5 μm.

In a multi-layer version of the lens, at least some of the modified tracks in the first layer may have an optical path length that is at least 0.1 wavelength greater than the optical path length of the unmodified tracks, where the wavelength is light about the first wavelength. The modified track of the second layer may have an optical path length of at least 0.1 wavelength longer than the optical path length of the non-modified track for light of a second wavelength different from the first wavelength by at least 50 nm. There may also be a third layer, wherein the optical path lengths differ by at least 0.1 wavelength for light of a third wavelength, wherein the third wavelength differs from the first and second wavelengths by at least 50 nm. For example, the first layer may be for green light, the second layer for red light, and the third layer for blue light.

In the multi-layer approach of the present invention, the first layer may focus the light to a first focal point. The second layer may focus light at a second focal point spaced apart from the first focal point, and the additional layer may focus light at other additional points.

Typically, the materials used for the lens include a polymer matrix. An absorber may optionally be used, preferably in an amount of at least 0.01% by weight of the material, wherein the absorber is for light at the wavelength of the laser beam.

The system also includes a device for modifying the optical properties of the polymeric disc to form a lens. The apparatus may include a laser emitting a pulsed light beam, a modulator controlling the pulse rate of the light beam, a focusing lens for focusing the light beam into a first region of the disc, and a scanner distributing the focused light beam to a plurality of tracks in the region. There are also holders for the lens and means for moving the disc so that multiple areas of the disc can be modified. Preferably, the modulator generates pulses at a repetition rate of between 50-100 MHz. The pulses emitted by the laser may have a duration of about 50 to about 100 femtoseconds and an energy level of about 0.2 nJ. The focusing lens may be a microscope objective focusing to a spot size of less than 5 μm.

The scanner may be a raster scanner or a flying spot scanner and, in the case of a raster scanner, covers a field of view of about 500 μm.

The system also provides methods of forming these lenses. In forming the lens, a disc formed of an optical material is fixed, and then a modified track is formed in the fixed disc using a laser beam.

The method may comprise the steps of: the method includes emitting a pulsed light beam from a laser, controlling a pulse rate of the light beam with a modulator, focusing the light beam in a first region of a lens, distributing the focused light beam to a plurality of tracks in the region, and moving the lens to modify the tracks in the plurality of regions of the disc.

The methods and systems may also be used to modify the optical properties of a lens, such as an intraocular lens, a contact lens, or a natural lens located in the posterior or anterior chamber. This can be effected by creating modified trajectories in the lens as if they had used the same procedure as used for modifying the lens, which was used prior to lens implantation. One difference is that the in situ lens is not moved to modify different areas, but rather the focusing system of the device is used to illuminate different areas of the in situ lens. During in situ treatment, the patient's eye may be stabilized according to conventional techniques used during ophthalmic surgery.

Drawings

These and other features, aspects, and advantages of the present invention will become better understood with regard to the following description, appended claims, and accompanying drawings where:

FIG. 1A is a front elevational view of an intraocular lens having features of the present invention;

FIG. 1B is a top plan view of the lens of FIG. 1A;

FIG. 2 schematically shows a portion of an intraocular lens body with two layers of modified trajectories;

FIG. 3 schematically illustrates a lens body having multiple layers of modified trajectories, some of which are formed after the lens is placed in the eye;

FIG. 4A is a schematic view of a layer of the lens of FIG. 1 modified to produce a spherical focusing effect;

FIG. 4B is a top plan view of the layer shown in FIG. 4A;

FIG. 4C is a schematic view of a layer of the lens of FIG. 1 modified to produce an aspheric focusing effect;

FIG. 4D is a schematic view of a layer of the lens of FIG. 1 providing a defocus meridian (meridian) to accommodate astigmatism;

FIG. 4E is a top plan view of the layer of the lens of FIG. 4D at the horizontal meridian;

FIGS. 5 and 6 schematically illustrate the principle for forming the modified track;

FIG. 7 schematically shows a layout of an apparatus for forming the above-described lens according to the present invention;

FIG. 8 shows a flow chart of an algorithm used in the device of FIG. 7;

FIG. 9 graphically illustrates the effect of including a UV absorber in the material used to form the lens;

FIG. 10A graphically illustrates the change in refractive index of a modified track as a function of laser pulse energy;

FIG. 10B graphically illustrates the refractive index change of the modified lens as a function of the number of pulses of the laser beam at a fixed pulse energy;

FIG. 11 schematically illustrates the formation of a lens according to the present invention using a layered raster scan process;

FIG. 12 schematically illustrates the formation of a lens according to the present invention using a layered flying spot scanning method;

FIG. 13 schematically illustrates a process of producing a refractive layer structure by a point-by-point variation of refractive index change; and

fig. 14 schematically shows how the natural lens can be modified in situ.

Detailed Description

SUMMARY

In accordance with the present invention, a customized intraocular lens, referred to as a customized artificial phase shift film (C-IPSM), is fabricated using a laser unit that generates a pulsed laser beam. More specifically, the laser unit optionally can generate 50MHz laser beam pulses, each pulse having a duration of about 100 femtoseconds and an energy level of about 0.2 to about 1 nanojoule. As contemplated by the present invention, the laser beam is focused at a focal point having a refractive index "n_o"the surface of the plastic material is moved. This changes the sub-surface layer by creating a pattern of material refractive index changes (Δ n).

Preferably, the customized intraocular lens (C-IPSM) is manufactured from a flat sheet of plastic having a first side and a second side and a thickness between the two sides of about 50 to about 400 mm. During the manufacture of a custom intraocular lens (C-IPSM), the laser unit changes the subsurface layer to a depth of only about 50 microns. The purpose of the layer with the altered material in this layer is to compensate for the optical aberrations of the patient to receive the C-IPSM. In particular, this compensates for optical aberrations introduced into the light beam by the optical system (e.g. the eye).

The pattern of refractive index changes produced in the plastic sheet is obtained by exposing the plastic material to the electronic interference and heat generated by the layer in a predetermined manner. In particular, this change in refractive index is achieved by sequentially focusing the laser beam onto a large number of adjacent tracks in the material. The result at each track is the Optical Path Difference (OPD) for the light passing through the spot. For a given material (e.g. plastic) with a given change in refractive index (Δ n) (e.g. Δ n ═ 0.01), and for a given distance through the material (e.g. 5 microns), the OPD (i.e. phase change) for light of wavelength (λ) can be established. In particular, an OPD of λ/10 can be established for every 5 micron track depth. Thus, the spot depth will be between 5-50 microns depending on the refraction required for each spot.

The change in the refractive index (Δ n) can vary for different track positions, for example between a minimum value Δ n of 0.001 and a maximum value Δ n of 0.01. Thus, depending on the refraction required, with the modulo 2 pi phase wrapping technique, values between 0.001 and 0.01 Δ n may be used.

Each track may be generated with a laser unit using a predetermined number of laser bursts (bursts), i.e. "i" bursts. Preferably, each burst comprises about 50 pulses and lasts about 1 microsecond. During each pulse burst, the material undergoes a substantially cylindrical change with a depth of about 5 microns and a diameter of about 1 micron. Thus, a trajectory contains at least one locus, and typically up to 10 loci. Typically, each burst induces an OPD of approximately one tenth of a wavelength (λ/10). For an "i" burst: OPD = i (x (λ/10)). Preferably, for the present invention, there is a variation of about λ/10 (i.e., "i" in the range of 1-10) per 5 micron of track depth. Consider, for example, a case where it is desired to generate 0.3 λ OPD. In this case, the laser unit is focused at a depth of 20 microns (i.e., i-3) for the initial burst. Thereafter, the laser unit refocuses onto the track twice more, withdrawing the focal point of the laser beam through a distance of 5 microns each time for each subsequent burst. The number "i" is chosen according to the amount of refraction required at the locus (e.g., i-2 according to 0.2 λ; i-7 according to 0.7 λ). The track may be created by advancing the focal point of the laser beam rather than retracting it.

According to another aspect of the invention, each track is generated with the laser unit using a different number of pulses per laser pulse burst using the variable Δ n. Each laser pulse burst produces a locus, with 1-10 loci present per track. Preferably, each burst comprises between 5 pulses and 50 pulses and lasts about 100 nanoseconds to 1 microsecond. During each pulse burst, the material undergoes a substantially cylindrical change with a depth of about 5 microns and a diameter of about 1 micron. Generally, as described above, each burst induces an OPD of approximately one hundredth of a wavelength (λ/100) to one 10-th of a wavelength (λ/10). Thus, by maintaining a certain number of pulses per pulse group, for example 5 pulses, at each subsequent position of a certain point, a predetermined OPD is obtained, in this embodiment one tenth of the wavelength (λ/10), resulting from (10 × λ/100). The change Δ n between the tracks produces a change in OPD when the femtosecond laser beam is moved in the transverse direction, i.e. parallel to the surface of the plastic film.

Once the refractive properties required to customize the IOL (C-IPSM) are determined, a template for the anterior surface layer of the IOL is calculated. The information is then sent to the manufacturing station and used to program the individual pixels of the iol multilayer. Subsequently, after implantation of the customized intraocular lens, incident light is refracted through optical elements in the intraocular lens eye to form an improved image on the retina of the eye.

The refraction of an incident beam by a customized intraocular lens (C-IPSM) is such that the optical path lengths of the individual beams of any incident beam appear substantially equal to each other. In this manner, the incident beam carrying the image information is compensated by the custom intraocular lens (C-IPSM) to account for the refractive aberrations of the pseudophakic eye as evidenced by the appropriate measurement data.

With respect to the optical properties of the microstructured surface layer of a customized intraocular lens (C-IPSM), several principles of refractive and diffractive optics may be employed to variously modify the properties of the customized intraocular lens (C-IPSM). Designs include refractive and diffractive phase ("GRIN") structures with or without phase wrapping. Specific embodiments of spherical, aspherical, achromatic, bifocal and multifocal are possible.

Crystalline lens

Lenses having features of the invention may be any type of lens implanted in the eye, including contact lenses placed in the anterior or posterior chamber, intraocular lenses, and corneal lenses. An IOL placed in the posterior chamber may typically be an intraocular lens when the natural lens is present and is a pseudolens in which the natural lens has been removed, for example, by cataract surgery. The present invention is also useful for modifying a lens in situ, including lenses such as contact lenses in the anterior chamber, IOLs in the posterior or anterior chamber, natural cornea, and natural lenses.

With reference to fig. 1A and 1B, an intraocular lens 10 having features of the present invention includes a central disc-shaped body 12 having an anterior surface 14 and a posterior surface 16. Preferably, both the anterior surface 14 and the posterior surface 16 are substantially planar, i.e., they have little or no curvature, such as concave or convex curvature. Plano-plano intraocular lenses may be formed using the present techniques. As is conventional with many intraocular lenses, there may be a pair of haptics (haptics) 18 for securing the lens in the posterior chamber.

The terms "anterior" and "posterior" refer to the surfaces of the lens when normally placed in a human eye, with the anterior surface 14 facing outward and the posterior surface 16 facing inward toward the retina. Lens 10 has an optical axis 19, which is an imaginary line defining a path along which light propagates through lens 10. In the solution of the invention shown in fig. 1A and 1B, the optical axis 19 coincides with the mechanical axis of the lens, but this is not essential.

While it is preferred that all of the optical effects of the lens be provided by modified trajectories in the body 12, as described below, corrective optical effects may also be provided in a conventional manner, such as by having the anterior surface, the posterior surface, or both curved, such as convex, concave, or have compound curvatures. The optical correction need not be provided entirely by the modified track according to the invention, although this is preferred.

Lenses having features of the invention can be used to correct vision errors such as myopia (nearsightedness), hyperopia (farsightedness) and astigmatism. The lens may be aspherical and/or faceted.

The body 12 of the lens 10 is made of an optical material, which is any material now or later available that is suitable for making a lens for implantation in an eye. The material is typically polymeric. The material used for the body 12 exhibits a change in refractive index when treated with a laser, as described in detail below.

Non-limiting examples of such materials include materials used in the manufacture of ophthalmic devices, such as contact lenses and IOLs. For example, the present invention is applicable to siloxy-containing polymers, acrylic polymers, other hydrophilic or hydrophobic polymers, copolymers thereof, and mixtures thereof.

Non-limiting examples of siloxy-containing polymers that can be used as optical materials are described in the following U.S. patents: 6,762,271, respectively; 6,770,728, respectively; 6,777,522, respectively; 6,849,671, respectively; 6,858,218, respectively; 6,881,809, respectively; 6,908,978, respectively; 6,951,914, respectively; 7,005,494, respectively; 7,022,749, respectively; 7,033,391, and 7,037,954.

Non-limiting examples of hydrophilic polymers include polymers comprising the following units: n-vinylpyrrolidone, 2-hydroxyethyl methacrylate, N-dimethylacrylamide, methacrylic acid, poly (ethylene glycol monomethacrylate), 1, 4-butanediol monovinyl ether, 2-aminoethyl vinyl ether, di (ethylene glycol) monovinyl ether, ethylene glycol butyl vinyl ether, ethylene glycol monovinyl ether, glycidyl vinyl ether, glycerol vinyl ether, ethylene carbonate and vinyl carbamate.

Non-limiting examples of hydrophobic polymers include polymers containing the following units: methacrylate of alkyl group having 1 to 10 carbon atoms (e.g., methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, octyl methacrylate or 2-ethylhexyl methacrylate; preferably methyl methacrylate for controlling mechanical properties), acrylate of alkyl group having 1 to 10 carbon atoms (e.g., methyl acrylate, ethyl acrylate, propyl acrylate or hexyl acrylate; preferably butyl acrylate for controlling mechanical properties), acrylate of aralkyl group having 6 to 40 carbon atoms (e.g., 2-phenylethyl acrylate, benzyl acrylate, 3-phenylpropyl acrylate, 4-phenylbutyl acrylate, 5-phenylpentyl acrylate, 8-phenyloctyl acrylate or 2-phenylethoxy acrylate; preferably 2-phenylethyl acrylate for increasing refractive index), and a methacrylate of an aralkyl group having a carbon number of 6 to 40 (e.g., 2-phenylethyl methacrylate, 3-phenylpropyl methacrylate, 4-phenylbutyl methacrylate, 5-phenylpentyl methacrylate, 8-phenyloctyl methacrylate, 2-phenylethoxy methacrylate, 3-diphenylpropyl methacrylate, 2- (1-naphthylethyl) methacrylate, benzyl methacrylate or 2- (2-naphthylethyl) methacrylate; preferably 2-phenylethyl methacrylate for increasing the refractive index).

Preferred materials are hydrophobic acrylic polymers made by crosslinking N-benzyl-N-isopropylacrylamide, ethyl methacrylate, and butyl acrylate with ethylene glycol dimethacrylate.

The material may optionally comprise a uv light blocker, for example an acrylic acid derivative of benzotriazole.

For a typical IOL, body 12 has a diameter of about 6mm and preferably has a thickness 20 of about 50 μm to about 400 μm and most preferably about 250 μm. This is less than the thickness of conventional IOLs. When folding lens 10 to place it in the posterior chamber, the surgeon may make a smaller incision than a conventional lens because it is thinner. This can increase patient safety and is believed to result in reduced post-operative recovery time, as well as reduced surgically-induced astigmatism. Also in the present version where both the anterior and posterior surfaces are planar, the lens is easily inserted, making some cataract surgeries less traumatic.

The optical effect provided by lens 10 is a result of the presence of a modified track in body 12, where the modified track has been formed by a laser beam that causes the modified track to have a different refractive index than the pre-modified lens material.

Fig. 2 shows a portion of an exemplary lens body 12 having two spaced apart planar layers, an upper layer 22 and a lower layer 23, generally parallel to the anterior surface 14 of the lens body 12. The thickness of the layers 22 and 23 is preferably 50 μm. Only a portion of each layer is shown and exemplary modification tracks are shown only for the upper layer 22. The layer 22 contains exemplary adjacent modified tracks 24a-24 j. Each track 24 is cylindrical with a diameter of about 1 μm, the axis of which is generally parallel to the optical axis 19 of the lens. Each track 24a-j contains one or more sites 26 that are formed by a single pulse from a laser. The height of each site is typically about 5 μm, and thus the height of the modified trajectory ranges from about 5 to about 50 μm. As shown in fig. 2, trace 24a contains 10 sites 26 and trace 24b contains 9 sites, which continues to trace 24j containing 1 site.

A change in the refractive index of the material present in the modified track results in a change in the optical path length. In particular, the optical path length of each modified track is increased by about 0.1 wave for a selected wavelength of light compared to the optical path length of the unmodified track. Typically, green light having a wavelength of about 555nm is the basis for the modification, since the human eye typically receives light of this wavelength optimally. Thus, each modified track has an optical path length of about 0.1 to about 1 wave greater than the optical path length of the unmodified track, where the wavelength is relative to light of 555nm wavelength.

Preferably, there are sufficient modification trajectories such that at least 90%, more preferably at least 99%, of the light projected onto the anterior surface 14 of the lens 10 in a direction substantially parallel to the optical axis 19 passes through at least one modification trajectory 24.

Fig. 3 shows a schematic of a multi-layer microstructured customized intraocular lens 10 that is film-like and exhibits a disc-like planar appearance with a diameter 62 of about 6mm and a width 64 of about 500 μm. The refractive properties of microstructured customized intraocular lenses are recorded in thin layers, indicated at 66-88, which are typically 50 μm thick. Initially, a posterior layer of depth 65 is created, for example, between posterior surface 16 and flat surface 69. Layers 72, 74, 76, 78, 80, 82, 84, 86, and 88 are microstructures, respectively. During the step of fine tuning the refractive properties of the implanted customized intraocular lens in vivo, the additional layers 66, 68 and 70 may be microstructured, covering the anterior portion of the artificial phase shift film between planes 69 and 71, with a thickness 67.

Each layer 66-88 contains modified loci, and typically more than 1,000,000 modified loci, and up to about 30,000,000 loci, each layer typically lying in a plane substantially parallel to the anterior surface 14 of the lens body 14.

Figure 4 shows a pattern of modified tracks for achieving different optical effects. The layers shown in figures 4A and 4B provide an amount of sphere accommodation of about +0.4 diopters. It comprises three annular rings 402, 404 and 406 concentric with the optical axis 19 and surrounding a central region 408. Thus, the tracks are modified into a circular pattern concentric with the optical axis. The outer edge of the outermost radius ring 402 is located at r₄Which is 3mm from the optical axis 19, i.e. it is at the peripheral edge of the body 12. Outer edge r of second ring 404₃2.5mm from the optical axis 19. The outer edge of the third ring 406 is located at r₂Which is 2mm from the optical axis 19. Outer edge r of central portion 408₁At 1.4 mm. Each ring is made up of a number of adjacent modified tracks, wherein the number of bits in each track increases as the track gets closer to the optical axis 19. Thus, the modified trajectory at the outer edge of the first ring 402 has one locus and a height of about 5 μm, while the modified trajectory closest to the optical axis 19 has 10 loci and a height of about 50 μm.

The layers shown in fig. 4C are patterned to provide an aspheric focusing effect. In this layer, the innermost ring 406 'and the central region 408' have the same pattern as the ring 406 and the central region 408, respectively, in fig. 4A. However, the outer rings 402 'and 404' have opposite modification trajectories, with more points for modification trajectories further from the optical axis 19 than for modification trajectories radially inward. Because of r shown in FIG. 4C₁、r₂And r₃As with the solution in fig. 4A, the top plan view of fig. 4B is also applicable to the arrangement shown in fig. 4C.

Fig. 4D shows the pattern of the modified trajectory to accommodate astigmatism and/or toricity (toricitytaken) at the horizontal meridian of the lens. In this scheme, the modified trajectory of any single loop of all the rings 402 ", 404", and 406 "and the central region 408" has a lower height closer to the optical axis 19, exhibiting a defocusing effect at the horizontal meridian.

A top plan view of the layer of fig. 4D is shown in fig. 4E, where the layer shown in fig. 4D is horizontally disposed. The vertical meridian of the astigmatic connector of figure 4D is the same as that shown in figure 4A. The horizontal meridian provides-0.4 power, while the vertical meridian provides +0.4 power. At a 45 ° diagonal, there is no refraction effect.

There is a smooth transition between the different regions of the layer shown.

Each track has a very small diameter, in the order of about 1 μm. The transition from the outside of the loop to the inside of the loop need not be a steady step-down in the number of sites, as there may be multiple modification trajectories with the same number of sites adjacent to each other.

The optical effect provided by lens 10 can be easily increased or decreased by changing the number of loops. For example, with the lens schematically shown in FIG. 4A, each ring provides 0.1 power, so that the lens shown in FIG. 4A provides 0.4 power. To manufacture a lens with 10 powers where each ring contributes 0.1 diopters, the lens is manufactured with approximately 100 rings, 99 of which have the same general configuration as rings 402, 404, and 406 in fig. 4A, and a central ring having the configuration of central ring 408 shown in fig. 4A. However, since there are more rings in the same surface area, the width of each ring is much smaller than the ring in FIG. 4A.

Fig. 5 and 6 illustrate principles of a modulo 2 pi phase wrapping technique that may be used to characterize the present invention. In particular, the shaped microstructure is created to compensate for path length differences within an array of adjacent rays, such as rays 542, 544, and 546, such that all adjacent individual beams 542, 544, and 546 are in phase with each other. For the purposes of this discussion, each of adjacent beams 542, 544, and 546 are considered exemplary.

In fig. 5, the sinusoidal nature of first light beam 542 and second light beam 544 is shown as a function of time. If beams 542 and 544 are in phase with each other, which is not the case in FIG. 5, then second beam 544 will be shown as overlapping first beam 542. However, as shown, beams 542 and 544 are out of phase with each other, and this phase difference is shown as phase shift 590. Conceptually, the phase shift 590 may be considered a difference in time or propagation distance. For example, at a particular point in time 592, first beam 542 is at a location in free space. However, due to the phase shift 590, the second beam 544 is not at the same position until a subsequent point in time 594. For the case shown in FIG. 5, the magnitude of phase shift 590 between first beam 542 and second beam 544 is less than 2 π when considering that first beam 542 will propagate from point in time 592 to point in time 596 through a complete cycle or cycle of 360 (2 π radians).

For first light beam 542 and third light beam 546 shown in fig. 6, point in time 592 of first light beam 542 corresponds to point in time 598 of third light beam 546. Thus, the total phase shift 604 that exists between first light beam 542 and third light beam 546 is greater than 2 π. As envisioned, for the present invention, the total phase shift 604 actually includes a modulus phase shift 500 equal to 2 π and an individual phase shift 502 less than 2 π. With this representation, the total phase shift 604 between any two light beams can be represented as the sum of a modulo phase shift 500 equal to n2 π (where "n" is an integer) and an individual phase shift 502 less than 2 π, referred to as a modulo 2 π phase shift. Thus, the integer "n" may take on different values (e.g., 0, 1,2, 3, … …), specifically n being 0 for light beam 544 (fig. 3A) and 1 for light beam 546 (fig. 3B). In all cases, the total phase shift 604 for each beam 544, 546 is determined by comparing it to the corresponding beam 542 as a reference. The modulus phase shift 500 is then subtracted from the total phase shift 604 to yield the individual phase shifts 502 for the particular beams 544, 46. However, the total phase shift is first determined 604.

Referring to fig. 4A, at each track, the modulus phase shift 500 (= n × 2 pi) is subtracted from the total phase shift 604 to obtain, for example, the individual phase shift 502 in fig. 4A, the modulus phase shift 500 being equal to 0 × 2 pi ═ 0 in the central region, and being equal to 0 in the second region (r = n × 2 pi), in the second region₁To r₂) Equal to 1X 2 pi, in a third region (r)₂To r₃) Equal to 2 × 2 pi ═ 4 pi, and in the fourth region (r)₃To r₄) Equal to 3 × 2 pi ═ 6 pi. A single phase shift 502 (0-2 pi, corresponding to 0.0 to 1.0 wave) is recorded in the track, equal to 5-50 μm deep.

Thus, with further reference to FIG. 4A, the local phase shift as a function of distance from the pupil axis is plotted, as added by the microstructured customized intraocular lens, from a2 π phase shift equal to 1.0 wave at the optical axis 19 to a radial position r₁0 of (3). It is assumed that the initial beam incident on the microstructured customized intraocular lens is collimated and appears as individual rays having the same optical path length shaped as a planar light wave. As a result of the propagation of individual rays through the microstructured customized intraocular lens, a focused light wave is generated. In the central part of the beam, radius r₁Inside the defined region, the optical phase shift changes quadratically with the distance from the optical axis. At position r₁At this point, a zero phase shift equivalent to 0.0 waves is achieved. From radius r₁The laterally adjacent rays experience a2 pi phase shift equivalent to 1.0 wave, resulting in a characteristic 2 pi phase jump equivalent to 1.0 wave at the zone boundary of the modulo 2 pi phase wrapping technique. For FIG. 5, such phase jumps by an amount of 2 π, respectively a number of 2 π ("shift 500"), can be visualized as "catch the next wave", which is delayed by 2 π for a full cycle with respect to the neighboring beams. Generally, at each radial position r₁、r₃、r₄Here, a local phase shift jump of 2 pi corresponds to 1.0 wave, while between these jumps the phase changes quadratically, from a value of 2 pi equivalent to 1.0 wave to zero equivalent to 0.0 wave.

Generally, there are sufficient modification trajectories such that the refractive index of the body has been sufficiently modified to change the optical power of the body by at least +0.5 (+ 0.5 to + X) or at least-0.5 (-0.5 to-Y), where X may be about 48 and Y may be about 15.

In the multi-layer version of the present invention, the multiple layers are typically spaced apart by at least 1 micron, and preferably at least 5 μm.

In a multi-layer scheme, it is possible to optimize the different layers for light of a particular selected wavelength. For example, a first layer may be optimized for light of a first wavelength, such as green light, a second layer may be optimized for light of a second wavelength that differs from the first wavelength by at least 50nm, such as red light, and a third layer may be optimized for light of a third wavelength that differs from the first and second wavelengths by at least 50nm, such as blue light.

Also, different layers may be formed to focus light at different focal points.

Another use of multiple layers is to subject a single layer to multiple optical corrections, rather than all of the vision correction in a single layer. Thus, it is possible for the first layer to provide a diopter adjustment while the other layers provide other optical corrections such as toric adjustment or aspheric adjustment. Thus, the first layer may provide diopter adjustment, the second layer trajectory may provide toric adjustment, and the third layer may provide aspheric adjustment.

System for manufacturing and modifying lenses

The present invention uses very short laser pulses of sufficient energy to be tightly focused on an optically polymerized material to form a lens. The high density of light at the focus causes non-linear absorption of photons (typically multiphoton absorption) and results in a change in the refractive index of the material at the focus. The area of the material just outside the focal area is minimally affected by the laser. Thus, regions of the optically polymeric material are selected and modified with a laser, thereby obtaining a positive change in the refractive index of these regions.

Thus, a lens can be formed by irradiating selected regions of an optically polymerized material with a focused visible or near-IR laser having a pulse energy from 0.05nJ to 1000 nJ. The illuminated area shows little or no scattering loss, which means that the structures formed in the illuminated area are not clearly visible without a suitable magnification of the contrast enhancement.

The pulse energy of the focused laser used in the method depends in part on the type of optical material being irradiated, how much change in refractive index is required, and the type of structure that is desired to be imprinted within the material. The selected pulse energy also depends on the scan rate at which the structure is written to the optical material. Generally, larger scan rates require larger pulse energies. For example, some materials require pulse energies of 0.2nJ to 100nJ, while other optical materials require pulse energies of 0.5nJ to 10 nJ.

The pulse width is maintained such that the pulse peak power is sufficiently strong to exceed the nonlinear absorption threshold of the optical material. However, the glass of the focusing objective used can increase the pulse width significantly due to the positive dispersion of the glass. A compensation scheme is used to provide a corresponding negative dispersion that can compensate for the positive dispersion caused by the focusing objective. Thus, the term "focused" in this application refers to the focusing of light from a laser within an optically polymeric material using a compensation scheme to correct for the positive dispersion introduced by the focusing objective. The compensation scheme may comprise an optical arrangement selected from: at least two prisms and at least one mirror, at least two diffraction gratings, a chirped mirror, and a dispersion compensation mirror to compensate for positive dispersion introduced by the focusing objective.

Pulses with pulse energies of 0.01nJ-100nJ, or 0.01nJ-50nJ, and pulse widths of 4fs-200fs can be generated using a compensation scheme with a focusing objective. In some cases, laser pulses with energies of 0.2nJ-20nJ and pulse widths of 4fs-100fs can be advantageously generated. Alternatively, laser pulses with energies of 0.2nJ-10nJ and pulse widths of 5fs-50fs can be advantageously generated.

Lasers can produce light in the wavelength range from violet to near infrared radiation. In various embodiments, the laser light has a wavelength in the range of 400nm to 1500nm, 400nm to 1200nm, or 600nm to 900 nm.

Fig. 7 schematically shows a preferred apparatus 702 for forming a modified trajectory. The apparatus 702 comprises a laser 704 (preferably a femtosecond laser used in a 2-photon microscope), a control unit 706, a scanning unit 708, a mount 710 for the lens disk 12, and means 712 for moving the disk 12 in which the modified tracks are formed. Suitable lasers are available from the company Calmar Laser, Senyvale, Calif. Each pulse emitted by the laser may have a duration of about 50 to about 100 femtoseconds and an energy level of at least about 0.2 nJ. Preferably, laser 704 produces about 5 million 780nm wavelength, about 50fs pulse length pulses per second, each pulse having a pulse energy of about 10nJ, the laser being a 500mW laser. The emitted laser beam 721 is directed by the turning mirror 722 through an acousto-optic modulator 724, which controls the pulse frequency, which is typically about 50MHz-100MHz repetition rate. The laser beam 721 typically has a diameter of 2mm when emitted by a laser. The laser beam 721 then propagates through the scanning unit 708, which spatially distributes the pulses into multiple beams. The pattern may be a raster scan pattern or a flying spot pattern. The scanning unit 708 is controlled by a computer control system 726 to provide the desired configuration of modified tracks in the disk 12.

The laser emits a beam 721 having a diameter of about 2 to about 2.5 nm. The beam 721 exits the scanner 708 and is then focused to a size suitable for forming modified tracks, typically tracks having a diameter of about 1 to about 3 μm. Focusing can be achieved with a telescopic lens pair 724 and 744 and a microscope objective 746, with another steering mirror 748 directing the beam from the lens pair to the microscope objective. The focusing microscope objective may be a 40 x/0.8 objective with a working distance of 3.3 mm. The scanning and control unit is preferably a Heidelberg spectra HRA scanning unit available from Heidelberg Engineering, Heidelberg, Germany.

The optics in the scanning unit may modify the area having a diameter of about 150 to about 450 μm without having to move the disk 14 or optics. Typically, a region of a monolayer 50 μm thick may be microstructured in about 1 minute.

To modify other areas of the disc 12, the holder 710 needs to be moved by the moving means 712. The moving device 712 may move in the "z" direction for providing modified trajectories in different layers, and may also move in the "x" and "y" directions for processing different regions at the same depth. The movement device 712 serves as a precision positioning system to cover the full diameter of the artificial wafer disk, which is typically 6mm in diameter.

The fixture 710 may be a stent, a belt with lens-sized grooves, a tray with grooves for the lens, and any other structure that can hold the lens sufficiently securely for forming the desired refraction pattern.

The movement means may be any mechanical mechanism, typically driven by motors, which provides movement in the x, y and z directions, i.e. three-dimensional movement. The motor may be a stepper motor. Typically, the movement may be up to about 10 mm/sec.

The lens manufacturing process uses steps positioned by xyz from one scan region (typically 450 μm diameter) of a2 photon microscope (raster scan or flying spot scan) to the next scan region. A 2-photon microscope provides depth scanning. Typically, one refractive layer can be done in the 2 photon microscope range. Alternatively, the z-positioning is provided by mechanical z-positioning to provide extended reach of deeper layers in the disc 14.

The control unit 706 may be any computer that includes a memory, a processor, a display, and an input device such as a mouse and/or a keyboard. The control unit is programmed to provide the desired modified track pattern in the disc 12 by providing control instructions to the scanning unit 708 and, if necessary, the moving means 712.

FIG. 8 shows an exemplary procedure for forming a disk, where the beam is held stationary (i.e., without the use of a scanner) and the target disk is mechanically moved. When the procedure is started, step 801 prompts the user to select the desired lens. Next, during a laser jump at step 802, the user provides the desired speed for scanning the disk 14. At step 803, the program accepts input only if the computer determines that the speed is a safe speed (typically 4mm or less of travel distance per second). Next, at step 804, the program sets the maximum power used by the laser and prompts the user to confirm that it is going on. At this stage, the program provides the user with a final opportunity to avoid writing the lens prior to step 805. If the user chooses to exit the write, the program terminates. Otherwise, at step 806, the program modifies the log file to record variables appropriate for record keeping and advancing.

The laser starts at a position at the end of the x and y directions, which constitutes the starting position. Each layer in the modified lens can be viewed as a stack of microlayers having a depth equal to the thickness of the site. On a given microlayer, the laser advances across one dimension (e.g., x) while keeping the other two dimensions (e.g., y and z) constant, thereby writing a series of sites. In step 807, the program begins writing each series by finding the grid location that constitutes the starting point of the current series. Next, at step 808, the program writes the series where appropriate. When the program scans until the laser reaches the periphery of the established series, it modifies the log file to reflect that the series is complete, step 809. At step 810, the program then queries the input instructions to determine if there is a subsequent series to be formed. The process continues until all series of modified tracks in a given microlayer are formed. Whenever a new series needs to be manufactured, the program advances the second variable (e.g., y) and resets the first dimension (e.g., x) to start a new sequence 807. Once the laser has completed scanning all the grid positions of the microlayers (each position has been considered in turn and the series has been written at the appropriate time), the program's writing to that microlayers is complete. The scanner then resets the first and second dimensions to their original positions, thereby returning the laser to its starting position, step 811. At step 812, the program updates the log file to show that the layer is complete.

At step 813, the program then queries to determine if more micro-layers are needed to obtain the lens desired by the user. If more micro layers are needed, the program advances to the third dimension (e.g., z) and repeats the above process, starting with the first grid position for the first line of the new layer 817. If no more microlayers are needed, the program returns the laser to its original starting position for all three dimensions at step 814, modifies the log file to reflect write completion and system time at step 815, and terminates execution. Once a layer, typically having 1-10 microlayers, is completed, any additional layers that need to be prepared can be prepared using the same process. In an optional procedure, the focal point of the scanner 708 may be moved in the z-direction (depth) to form a deeper site. Typically all sites are formed to the same depth and then all sites are formed to the next depth within the layer until all sites within the layer are complete.

The memory may be one or more devices for storing data, including Read Only Memory (ROM), Random Access Memory (RAM), magnetic disk storage media, optical storage media, flash memory devices, and/or other machine-readable media for storing information.

Control may be implemented by hardware, software, firmware, middleware, microcode, or a combination thereof. When implemented in software, firmware, middleware or microcode, the program code or code segments to perform the necessary tasks may be stored in a machine readable medium such as a storage medium or other storage. The processor may perform the necessary tasks. A code segment may represent a process, a function, a subroutine, a program, a routine, a subroutine, a module, a software package, a class or combination of instructions, data structures, or program statements. A code segment may be coupled to another code segment or a hardware circuit by passing and/or receiving information, data, arguments, parameters, or memory contents. Information, arguments, parameters, data, etc. may be passed, forwarded, or transmitted via a suitable means including memory sharing, message passing, token passing, network transmission, etc.

Optionally, an adaptive optics module (AO module) can be used to simulate the effect of refractive correction for image sharpness and depth of focus. The AO module may consist of a phase point compensator and a movable mirror for pre-compensating the single beam generated by the laser 704. Adaptive optics for compensating asymmetric aberrations in a beam are used in the invention described in my U.S. patent 7,611,244. A method and apparatus for pre-compensating for human refractive properties with adaptive optical feedback control is described in my us patent 6,155,684. The use of movable mirrors is described in my us patent 6,220,707.

The optical resolution (Δ xy, Δ z) of the two-photon signal is equal to: 2 Δ xy ═ 2x (0.325 λ)/(NA0.91) =622nm (1/e2 diameter), Δ z 2 × 0.532 λ xl/(n-2-NA2) =3102nm (NA = numerical aperture, e.g. 0.8). This yields the site size.

A typical scan area in raster scan mode is equal to: field of view of 150 μm: 1536 × 1536 pixels at 5Hz or 786 × 786 pixels at 10 Hz; field of view of 300 μm: 1536 × 1536 pixels at 5Hz or 786 × 786 pixels at 9 Hz; field of view 450 μm: 1536 × 1536 pixels at 5Hz or 786 × 786 pixels at 9 Hz.

For quality control in forming the modified track, a laser may be used to generate light from autofluorescence of the lens material. The modified trajectory produces more fluorescence than the unmodified material. If no suitable increase in emitted fluorescence is detected, this indicates that the process for forming the modified trajectory has not proceeded correctly. A suitable System for detecting autofluorescence is shown in FIG. 7 of my co-pending U.S. patent application 12/717,866, filed on even date herewith And entitled "System for Characterizing A Cornea And Observation of ophthalmic lenses" (patent docket 19330-1). Also, using the detected modified trajectory with the reference position, the detected autofluorescence may be used to position the focal point of a laser beam system from the microscope objective 746 to form additional trajectories.

The optical effect provided by the lens 10 for any particular patient can be determined using conventional lens design techniques. See, e.g., the techniques described in U.S. Pat. Nos. 5,050,981(Roffman), 5,589,982(Faklis), 6,626,535(Altman), 6,413,276(Werblin), 6,511,180(Guirao et al), and 7,241,311(Norrby et al). Suitable techniques are also described in my aforementioned co-pending U.S. patent application 12/717,866 (docket No. 19330-1).

Optionally, an absorber of light at the laser beam wavelength may be included in the disc to reduce the amount of energy required to form the modified track. For this purpose, it is desirable to use as little energy as possible, as exposure to excess energy can result in cracking or other undesirable mechanical alteration of the body 12. Exemplary UV absorbers that can be used with the laser 704 are derivatives of benzotriazole (benzotriazoles), such as 2- (5-chloro-2-H-benzotriazole-2-oxazole) -6- (1,1-dimethyl-ethyl) -4- (propylhexenyloxypropyl) phenol (2- (5-chloro-2-H-benzotriazol-2-yl) -6- (1,1-dimethyl-ethyl) -4- (propyloxypypropyl) phenol), and benzophenone derivatives such as 3-vinyl-4-phenylazophenylamine (3-vinyl-4-phenylazophenylamine), which is a yellow dye that absorbs at a wavelength of 390 nm. Preferably, the amount of UV absorber provided is at least 0.01% by weight, and up to about 1% by weight of the material used to form the lens body 12.

In fig. 9, the threshold energy (I) (nJ) for obtaining permanent structural changes in the plastic material is shown in dependence on the aromatic UV absorber concentration (%). The characteristic features show a strong correlation of the threshold energy with the UV absorber concentration, indicating that the local permanent structural changes increase with the UV absorber concentration due to the increased probability of two-photon absorption processes at a wavelength of 390nm, i.e. 780nm, with reference to the half-wavelength of the incident femtosecond laser pulse. The local interaction of the plastic host molecules leads to a local partial micro-crystallization of the plastic material, resulting in an increase Δ n of the refractive index n. At a 0.8% UV absorber concentration, as used in commercially available intraocular lens materials, a threshold energy of approximately 0.1nJ is required. In contrast, in undoped bulk plastic materials, a threshold energy of about 1nJ is required. The threshold energy is based on a spot size of about 1 μm in diameter, yielding about 0.01J/cm, respectively²And 0.1J/cm²The threshold laser fluence of (a).

Fig. 10 shows a laser material interaction process with femtosecond laser pulses to change the refractive index of a plastic material. In FIG. 10A, the change in refractive index Δ n is depicted as a function of pulse energy; in FIG. 10B, the change in refractive index Δ n is depicted as a function of the number of pulses in the focal region at a fixed pulse energy (e.g., 0.2 nJ)And (4) counting. Curve 1050 in fig. 10A shows that as the pulse energy increases from 0.1nJ to 8nJ, the change in refractive index n, Δ n, increases from about 0.1% to about 1.0%. The threshold at which the measurable change in refractive index n, Δ n, initially occurs is represented at location 1052 of curve 1050; at a pulse energy level of about 8nJ, corresponding to about 0.8nJ/cm²The photon interference threshold of the plastic material is reached, resulting in collateral damage and clouding of the material, promoting undesirable scattering losses of light transmitted through the plastic material. It can be seen from curve 1050 that the range of possible pulsed laser energies extends over two orders of magnitude, from 0.05nJ to 8nJ, enabling safe operation of the manufacturing process occurring at the lower end of the above range at a pulse energy of about 0.2 nJ. In undoped plastic materials, the safety range of the respective manufacturing process extends only over an order of magnitude. In addition, the low pulse energy facilitated by the addition of the UV absorber enables the material properties to be modified particularly smoothly, providing the artificial phase shift film with very low light scattering losses. In fig. 10B, curve 1060 shows that the cumulative effect of approximately 50 laser pulses in the focal volume (focal volume) produces a refractive index change Δ n on the order of 1%, with a low pulse energy of 0.2nJ chosen sufficient to obtain an optical path length difference of 1.0 wave (OPD = (Δ n) × thickness) in a 50 μm thick layer of plastic material.

In fig. 11, the manufacturing process of an intraocular phase shifting lens is schematically shown, wherein scanning unit 708 provides a raster scan pattern. A sequential positioning procedure showing 10 adjacent microlayers, each range comprising a densely spaced raster scan pattern, is illustrated. The stack 1170 of raster scanned microlayers 1176, 1178, 1180, 1182, 1184, 1186, 1188, 1190, 1192, and 1194 is shown in an x- (1172) and y- (1174) coordinate system and extends over a thickness 1202 of about 50 μm, i.e., up to about 5 μm for each microlayer. For the x (1198) and y (1199) dimensions, the lateral dimensions of the individual microlayers typically vary between 150 μm and 450 μm, changing the coverage of the laser pulse by a factor of 10 in each spot 1 μm diameter focal volume. Surface 1996 is the end of the layer.

In fig. 12, the fabrication of an artificial phase shifting lens is presented, wherein the scanning unit 708 provides a layered flying spot pattern. By way of example, a succession of 10 closely spaced circular scans is shown. The stack 1210 of circular scans 1216, 1218, 1220, 1222, 1224, 1226, 1228, 1230, 1232, and 1234 is shown in an x (1212) and y (1214) coordinate system and extends over a thickness 1238 of about 50 μm, i.e., the distance between individual circular scans or micro-layers is up to about 5 μm. The diameter 1236 of the circular scan can be as small as a few microns to about 450 μm so that the amount of coverage of the laser pulse per resolvable point can vary over a wide range. The speed of the dot sequence per row can be selected by varying the length of the scan line, if desired. Individual scan lines may exhibit various shapes. The resolution of the minimum scan detail may follow the resolution limit of a two-photon microscope of about 1 μm diameter, while the raster scanning procedure, as described for fig. 11, is limited to a resolution of about 150 μm, as given by the minimum raster scan range of a two-photon microscope. For practical applications, the manufacturing process of the artificial phase shift film is implemented in a compensation manner by a dual scanning system: most of this process is performed with a time-optimized raster scanning method, while the fine details of the required refractive properties are realized by a flying-spot scanner with an inherently high spatial resolution.

Fig. 13 illustrates the generation of a refractive layered structure by a point-by-point variation of the refractive index change Δ n. Generally, the refractive structures are included within a rectangular layer of the artificial phase shifting lens body 12. In fig. 13, a partially artificial phase shift film device is shown, which is composed of, for example, three adjacent strips 1344, 1348, 1350 and 1384 having widths of 150 μm, 300 μm and 450 μm, respectively. The overall dimensions of the body 14 region are up to 900 μm width 1340 and 50 μm thickness 1342. Because the standard number of pixels per scan line in the x and y directions was chosen to be 1536 x 1536 pixels, the pulse density on each scan line 1346, 1350, and 1354 reached 10 pulses per micron, 5 pulses per micron, and 3 pulses per micron, respectively, yielding a two-dimensional coverage factor of 100 pulses per spot, 25 pulses per spot, and 9 pulses per spot, respectively.

In-situ modification

Substantially the same methods and apparatus as described above may be used to modify the lens in situ. This includes intraocular lenses, corneal contact lenses, and natural lenses. In most cases, the lens already has optical characteristics, such as refractive power, toricity, and/or asphericity. This method is useful for fine tuning the lens and provides options for LASIK surgery.

For in situ modification, the apparatus of FIG. 7 is used, except that no lens holder 710 or means 712 for moving the lens is required. Of course, the focusing system may be changed to focus in additional regions when the range of modification provided by the focusing system covers only a portion of the lens being modified. Referring to fig. 14, a layer 1410 having a natural crystal diameter of about 6mm may be modified using the apparatus of fig. 7. Layer 1410 contains modification tracks, each having 1-10 sites. Typically, an area of about 2mm in diameter is modified to a scan range. The lens system of the device of fig. 7 is then moved in sequence to modify the additional region. Each region may have one or more modified trajectory planes.

The concepts of customized lens design and in situ modification can be used to achieve customized refractive correction in a living human eye by, for example, modifying the cornea. Alternatively, the refractive layer can be created in the human cornea using the methods described herein. For example, assuming a 1% refractive index change in the collagen tissue, exposing a 50 μm thick layer within the anterior stroma of the cornea is sufficient to promote refractive correction up to +/-20 diopters. Preferably, a series of modified track layers are located 100 μm-150 μm below the corneal surface. Correction of toric and aspheric refractive errors, as well as higher order optical aberrations, can be achieved. The calculation of the desired correction may be accomplished similarly to the case of a custom IOL design, by techniques well known in the art, or by techniques described in my aforementioned co-pending application 12/717,866 (patent file 19330-1). Based on autofluorescence imaging of different corneal tissues, the 2-photon microscope 704 can facilitate in situ tissue modification processes, which provides online procedural control.

The corneal tissue is heterogeneous compared to the polymeric lens material. The structure of the cornea can be observed by 2 photon microscopy using fluorescence and Second Harmonic Generation (SHG) imaging modes.

In fig. 14, the creation of a refractive layer in the front of the human lens is depicted. Preferably, layer 1410 is selected, which is located approximately 100 μm below the anterior lens capsule. The application for modifying the lens tissue is particularly suitable for producing multifocal vision in hyperopic eyes to promote near vision or to correct myopia (nearsightedness) or hypermetropia (farsightedness) and astigmatism (toricity).

In situ modification of corneal and lens tissues is believed to ultimately replace LASIK surgery, refractive lens Replacement (RLE) surgery, and intraocular lens surgery which offers another option that is non-invasive, patient friendly.

Although the invention has been described in detail with reference to preferred versions, other versions are possible. Therefore, the scope of the appended claims should not be limited to the description of the preferred versions contained therein.

Claims (15)

1. A lens sized for a human eye comprising:

a) a body formed of a polymeric optical material having a first refractive index, the body having opposing front and back surfaces and an optical axis; and

b) a plurality of adjacent modification tracks arranged in a form that forms adjacent patterned microstructures in the body layer, the polymeric optical material of the modification tracks having a second refractive index that is different from the first refractive index and that results from nonlinear absorption of resulting photons by exposure to focused laser light, each modification track being right cylindrical in shape and having an axis substantially parallel to the optical axis, and an axial depth of at least 5 μm;

wherein the adjacent patterned microstructures of the modified trajectory comprise phase shifting optical structures that modulate an optical effect of the lens, the phase shifting optical structures comprising a plurality of full wave, phase-wrapped regions that compensate for optical path length differences within adjacent ray arrays.

2. The lens of claim 1, wherein the adjacent patterned microstructures comprise refractive structures.

3. The lens according to claim 1 wherein adjacent patterned microstructures are disposed in a planar layer.

4. The lens according to claim 3 wherein the planar layer is substantially perpendicular to the optical axis.

5. The lens of claim 1, wherein the adjacent patterned microstructures comprise an annular ring pattern.

6. The lens of claim 1, wherein the optical effect comprises changing the optical power of the body by at least plus or minus 0.5.

7. The lens according to claim 1 wherein at least some of the modified tracks have an optical path length of from 0.1 to about 1 wavelength greater than the optical path length of the non-modified tracks, wherein the wavelength is with respect to light at a wavelength of 555 nm.

8. The lens according to claim 1 wherein at least some of the modified loci are configured in a substantially circular pattern about the optical axis.

9. The lens of claim 1, wherein the body comprises sufficient modification tracks configured as adjacent patterned microstructures formed in the body layer such that at least 90% of light projected to the anterior surface in a direction generally parallel to the optical axis passes through at least one of the modification tracks.

10. The lens according to claim 1 wherein there are at least 1,000,000 modified tracks in adjacent patterned microstructures formed in the body layer.

11. The lens according to claim 1 wherein the body layer is substantially perpendicular to the optical axis.

12. The lens according to claim 11 further comprising a second body layer substantially perpendicular to the optical axis, wherein there are at least two modified loci in the second body layer and the second body layer is spaced apart from the first body layer.

13. The lens of claim 1, wherein the posterior and anterior surfaces are substantially flat.

14. A lens according to claim 1 wherein the polymeric optical material comprises at least 0.01% by weight of a UV light absorber.

15. The lens according to claim 14 wherein the UV light absorber comprises a yellow dye that absorbs at a wavelength of 390 nm.