Abstract:
A system and method for modifying a characteristic of a contact lens is presented. A beam of ultra-short pulses is generated. The beam of ultra-short pulses is delivered to a desired location at the contact lens. A characteristic of the contact lens is modified at the desired location using the beam of ultra-short pulses.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Technical Field 
         [0002]    The present invention relates generally to the field of ultra-short pulsed lasers and, particularly to modifying characteristics of a contact lens using an ultra-short pulsed laser. 
         [0003]    2. Description of Related Art 
         [0004]    Fields of technological advancements in contact lenses include comfort and ability to correct vision of a wearer. One major factor in the comfort to the wearer is referred to as permeability. Permeability is a measure of an ability for oxygen to pass through the contact lens to reach a cornea of the wearer. Conventionally, permeability has been increased through advances in materials. Until the late 1970s, contact lenses were generally made from one of two materials. Hard contact lenses were made of polymethylmethacrylate (PMMA), while soft contact lenses were made of hydroxyethylmethacrylate (HEMA). HEMA is a hydrated polymer and contains about 38% water by weight. The contact lenses made of PMMA or HEMA provided clear vision and comfort with one critical problem. The critical problem being that these contact lenses hindered oxygen from reaching the corneas of contact lens wearers. In an absence of oxygen, the cornea can change adversely resulting in ocular irritation, fatigue, and general discomfort in some of the contact lens wearers. 
         [0005]    PMMA is now obsolete as a hard contact lens material and has been replaced by rigid plastics, most of which are hydrophobic materials with higher oxygen permeability relative to PMMA. The contact lenses made of these rigid plastics are known as rigid gas permeable (RGP) contact lenses. For the manufacture of soft contact lenses, HEMA is being replaced by polymers referred to as hydrogels that may contain about 80% water. The soft contact lenses made of hydrogels have higher oxygen permeability relative to HEMA. The introduction of new contact lens materials (e.g., RGP plastics and hydrogels) has lead to the manufacture of thinner contact lenses. The thinner contact lenses make wearing contact lenses more comfortable, while reducing the cost to manufacture. However, permeability remains a key issue with contact lenses. 
         [0006]    To correct the vision of the wearer, the contact lens refracts light that enters the eye of the wearer. The shape and material of the contact lens affect how the light is refracted. Conventionally, manufacturing both hard and soft contact lenses involves molding or stamping the contact lenses. Typically, the contact lenses are form fitted to diopter increments of 0.25. A diopter is a unit of measurement of refractive power of a lens. Furthermore, unique prescriptions for contact lenses are generally unavailable. The unique prescriptions may be prescriptions between 0.25 diopter increments or prescriptions for severe vision conditions. The severe vision conditions may include extreme farsightedness (hyperopia), extreme nearsightedness (myopia), astigmatism, or farsightedness due to ciliary muscle weakness and loss of elasticity in the crystalline lens (presbyopia). The dies required to form the contact lenses are expensive to produce and require periodic maintenance and replacement making them cost prohibitive for the unique prescriptions. 
       SUMMARY OF THE INVENTION 
       [0007]    Embodiments of the present invention provide systems and methods for modifying a characteristic of a contact lens. According to various embodiments, the characteristic may at least include permeability of the contact lens and corrective properties of the contact lens. In exemplary embodiments, a system may utilize an ultra-short pulsed laser to generate a beam of ultra-short pulses. The beam may be delivered to a desired location at the contact lens. In some embodiments, the beam may be coupled to an optical fiber and/or be directed by use of conventional optical elements. 
         [0008]    Upon delivery of the beam to the desired location, the characteristic of the contact lens may be modified. In one example, the characteristic may be modified at a surface of the contact lens by ablating a material from which the contact lens is made. Alternatively or additionally, the characteristic may be modified within the contact lens by damaging the material at the desired location. The beam may move relative to the contact lens such that, for example, features are created in the contact lens. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  illustrates an exemplary system to modify the characteristics of a contact lens. 
           [0010]      FIG. 2  illustrates an exemplary assembly of a contact lens and a cornea. 
           [0011]      FIG. 3  illustrates, in cross-section, an exemplary ablation process at a surface of a contact lens. 
           [0012]      FIG. 4  illustrates, in cross-section, an exemplary damaging process at a contact lens. 
           [0013]      FIG. 5  illustrates a contact lens having exemplary distributions of features created by the system. 
           [0014]      FIG. 6  illustrates, in cross-section, an exemplary contact lens modified by the system. 
           [0015]      FIG. 7  illustrates, in cross-section, an alternative contact lens modified by the system. 
           [0016]      FIG. 8  illustrates, in cross-section, another embodiment of a contact lens modified by the system. 
           [0017]      FIG. 9  illustrates, in cross-section, another exemplary contact lens modified by the system. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0018]    An ultra-short pulsed laser may provide a capability to modify characteristics of a contact lens. The characteristics may at least include permeability of the contact lens and corrective properties of the contact lens. The permeability may relate to gas permeability or liquid permeability. The corrective properties may relate to the way in which light is refracted by the contact lens to correct vision conditions. The ultra-short pulsed laser may be fabricated using techniques of laser fabrication known in the art. 
         [0019]    The ultra-short pulsed laser emits optical pulses having temporal lengths in a range of picoseconds to femtoseconds resulting in a very high electric field for a short duration of time. The emitted optical pulses may be referred to as ultra-short pulses. The ultra-short pulses may modify the characteristics of a material from which the contact lens is made. The ultra-short pulses may ablate, damage, or not affect the material. 
         [0020]    Ablating the material (also referred to as ablation) from which the contact lens is made may occur when a level of energy delivered to the material by the ultra-short pulses exceeds an ablation threshold of the material. Ablation may result in material removal by sublimation. In contrast to conventional laser machining, which uses continuous-wave lasers or long-pulsed lasers (e.g., lasers that emit optical pulses with temporal lengths greater than roughly 1 nanosecond), ablation using the ultra-short pulsed laser may generally be athermal. As such, virtually no heat may be transferred to the material during ablation. 
         [0021]    Damaging the material from which the contact lens is made may occur when the level of energy delivered to the material by the ultra-short pulses exceeds a damage threshold of the material and is less than the ablation threshold. Damaging the material may include altering an intensive physical property (also referred to as a bulk property) of the material such as a mechanical property of the material or an optical property of the material. The mechanical property may be, for example, porosity, density, hardness, Young&#39;s modulus, or strain. The optical property may be, for example, absorptivity, reflectivity, index of refraction, or transmittance. Damaging the material using the ultra-short pulsed laser may also generally be athermal. As those skilled in the art will recognize, the ultra-short pulsed laser may modify the index of refraction or other optical properties without causing ablation or other gross damage. For example, waveguide writing using ultra-short pulsed lasers may be utilized to modify the index of refraction or other optical properties. 
         [0022]    The material may not be affected (i.e., no material removed and no intensive physical property altered) when the level of energy delivered to the material by the ultra-short pulses does not exceed the ablation threshold or the damage threshold. The level of energy delivered may depend on the proximity to a focal point when the ultra-short pulses are focused by, for example, a lens. In one example, the level of energy at the focal point may exceed the ablation threshold resulting in ablation at the focal point, while the level of energy away from the focal point may not exceed the ablation or damage threshold. The focal point may be positioned at a surface of the material or within the material. Furthermore, the wavelength and/or output power at which the ultra-short pulsed laser operates may be tuned to provide increased control of the ultra-short pulses in ablating, damaging, or not affecting the material. 
         [0023]      FIG. 1  illustrates an exemplary system  100  to modify the characteristics of a contact lens  105 . The system  100  may comprise an ultra-short pulsed laser  110 , a beam modulator  115 , and a control unit  120 . As will be apparent to those skilled in the art, the system  100  may further include a positioning stage  125 . 
         [0024]    The ultra-short pulsed laser  110  emits a beam  130  of ultra-short pulses. In some embodiments, the beam  130  may be coupled to an optical fiber or other waveguide. One exemplary embodiment of the system  100  comprises a Bragg optical fiber, as described in U.S. Pat. No. 7,349,452, filed Apr. 22, 2005, and entitled “Bragg Fibers in Systems for Generation of High Peak Power Light,” which is hereby incorporated by reference. In other embodiments, the beam  130  may propagate without a waveguide and be directed or routed by use of conventional optical elements, such as lenses and mirrors. 
         [0025]    The beam modulator  115  may modulate the beam  130  providing control of whether the ultra-short pulses are allowed to propagate further in the system  100 . In some embodiments, the beam modulator  115  may mechanically block or unblock the beam  130 . A modulated beam  135  of ultra-short pulses may proceed from the beam modulator  115 . Similarly with the beam  130 , the modulated beam  135  may be coupled to an optical fiber or other waveguide according to some embodiments. Conversely, the modulated beam  135  may propagate without a waveguide and be directed or routed by use of conventional optical elements, such as lenses and mirrors, according to other embodiments. Subsequently, the modulated beam  135  may impinge on the contact lens  105 . In alternative embodiments, the beam modulator  115  may be integrated with the ultra-short pulsed laser  110  as a single component of the system  100 . 
         [0026]    According to various embodiments, the contact lens  105  may be any type of contact lens, conventional or otherwise. Because the ultra-short pulsed laser  110  may be tuned to produce ultra-short pulses that may ablate, damage, and/or not affect virtually any material, the material from which the contact lens  105  is made may generally be inconsequential. In some embodiments, the contact lens  105  may have a number of preexisting characteristics (e.g., the permeability and the corrective properties of the contact lens  105 ). In one embodiment, the contact lens  105  may be a standard prescribed lens that is commercially available. In another embodiment, the contact lens  105  may be a blank lens that is substantially cylindrical and provides no corrective properties prior to modification by the system  100 . 
         [0027]    In exemplary embodiments, the contact lens  105  may be held or placed upon the positioning stage  125 . The exemplary positioning stage  125  is configured to position the contact lens  105  such that the modulated beam  135  may impinge the contact lens  105  at a desired location. The desired location is a location at which ablation or damage to the material is desired. According to various embodiments, the positioning stage  125  may operate by linear translation in one, two, or three dimensions and/or by rotation. The positioning stage  125  may be designed to accommodate a variety of different shapes and sizes of contact lenses. The positioning stage  125  may also be configured to simultaneously hold a plurality of contact lenses, in accordance with some embodiments. In other embodiments, multiple positioning stages  125  may be included in the system  100 . 
         [0028]    In one alternative embodiment, a beam steerer may replace or augment the positioning stage  125 . The beam steerer may control the position of the modulated beam  135  relative to the contact lens  105  such that the modulated beam  135  may impinge the contact lens  105  at the desired location. In another alternative embodiment, an optical fiber to which the modulated beam  135  of ultra-short pulses is coupled to may be moved relative to the contact lens  105 . The modulated beam  135  emanating from an end of the optical fiber may subsequently be positioned proximate to the desired location. In yet another embodiment, a beam scanning system may substitute or augment the positioning stage  125 . 
         [0029]    The exemplary control unit  120  may be configured to coordinate and/or control the operation of at least the ultra-short pulsed laser  110 , the beam modulator  115 , and/or the positioning stage  125 . In one example, the control unit  120  may determine the wavelength and/or output power at which the ultra-short pulsed laser  110  operates. Furthermore, the control unit  120  may coordinate the operation of the beam modulator  115  with the operation of the positioning stage  125  such that the modulated beam  135  impinges the contact lens  105  only at the desired location. According to various embodiments, the control unit  120  may be a physical instrument or a virtual instrument (e.g., a LabVIEW virtual instrument). 
         [0030]      FIG. 2  illustrates an exemplary assembly  200  of a contact lens  205  and a cornea  210 . According to various embodiments, the contact lens  205  may abut the cornea  210  to correct vision conditions. An inner surface  215  of the contact lens  205  is adjacent to the cornea  210 . The contact lens  205  may be designed such that the inner surface  215  may be compatible with a curvature of the cornea  210 . Furthermore, an adequate level of oxygen for acceptable corneal health may pass through the contact lens  205  from an outer surface  220  to the inner surface  215  to reach the cornea  210 . 
         [0031]      FIG. 3  illustrates, in cross-section, an exemplary ablation process  300  at a surface  305  of a contact lens  310 . Boundaries  315  define a focal point  320  of the modulated beam  135  of ultra-short pulses. The level of energy delivered by the modulated beam  135  exceeds the ablation threshold at the focal point  320  resulting in the material at the focal point  320  to be ablated. It may be noted that the level of energy delivered by the modulated beam  135  away from the focal point  320  is low enough such that the material away from the focal point  320  is not affected. 
         [0032]    In some examples, as the material at the focal point  320  is ablated, ablation ejecta may form a cloud  325  of vaporized material. The cloud  325  may partially block the modulated beam  135  from impinging on the desired location, which may decrease a rate of material removal. In some embodiments, the cloud  325  may be removed from the vicinity of the focal point  320  by compressed gas or liquid, or be blown away from the focal point  320  by a fan. In other embodiments, the focal point  320  may constantly be moved away from the cloud  325  by, for example, moving the contact lens  310  using the positioning stage  125 . 
         [0033]    According to various embodiments, a feature  330  at the surface  305  may be created by moving the focal point  320  along the surface  305 . While the focal point  320  moves along the surface  305 , the material at the focal point  320  is ablated leaving a void. In one example, the focal point  320  is moved relative to the contact lens  310  by moving the contact lens  310  using the positioning stage  125 . In another example, the focal point  320  is moved relative to the contact lens  320  by moving the modulated beam  135  using the beam steerer. In yet another example, the system  100  may include both the positioning stage  125  and the beam steerer, such that both the modulated beam  135  and the contact lens  310  may be moved simultaneously. One skilled in the art would recognize that the feature  330  may be any shape or size at the surface  305  and that there may be multiple features  330  in the contact lens  310 . 
         [0034]    In various embodiments, a feature  335  may be created by moving the focal point  320  perpendicular to the surface  305 . Creating the feature  335  may be analogous to drilling a hole. In one example, the focal point  320  is moved relative to the contact lens  310  by moving the contact lens  310  using the positioning stage  125 . One skilled in the art would recognize that the feature  335  may extend part of the way through the contact lens  310 , as depicted in  FIG. 3 , or extend all of the way through the contact lens  310  joining the surface  305  to a surface  340 . Furthermore, there may be multiple features  330  and  335  in the contact lens  310 . 
         [0035]    The presence of the features  330  and  335  may modify the characteristics of the contact lens  310 . In alternative embodiments, processes of creating the features  330  and  335  may be combined. The combined processes may facilitate creating features with various dimensions parallel and perpendicular to the surface  305 . Further, the combined processes may facilitate creating complex features, described further herein. Additionally, in some embodiments, voids (e.g., the features  330  and  335 ) may be filled with materials other that the material from which the contact lens  310  is made, which have desirable characteristics. In one example, the voids may be filled with a liquid (e.g., artificial tears) to match the index of refraction of the material from which the contact lens  310  is made while increasing permeability of the contact lens  310 . 
         [0036]      FIG. 4  illustrates, in cross-section, an exemplary damaging process  400  at a contact lens  405 . Boundaries  410  define a focal point  415  of the modulated beam  135  of ultra-short pulses. The level of energy delivered by the modulated beam  135  exceeds the damage threshold and is less than the ablation threshold at the focal point  415  resulting in the material at the focal point  415  to be damaged. It may be noted that the level of energy delivered by the modulated beam  135  away from the focal point  415  is low enough such that the material away from the focal point  415  is not affected. 
         [0037]    According to various embodiments, a feature  420  within the contact lens  405  may be created by positioning the focal point  415  between surfaces  425  and  430 . In one example, the focal point  415  may be moved relative to the contact lens  405  by moving the contact lens  405  using the positioning stage  125 . In another example, the focal point  415  may be moved relative to the contact lens  415  by moving the modulated beam  135  using the beam steerer. One skilled in the art would recognize that the feature  420  may be any shape or size and that there may be multiple features  420  at the contact lens  405 . 
         [0038]    The presence of the feature  420  may modify the characteristics of the contact lens  405  according to some embodiments. In the example depicted in  FIG. 4 , the density of the material at the feature  420  may be changed, thus resulting in a consequential feature  435  being created at the surface  425 . The consequential feature  435  may alter a contour of the surface  425  without significantly increasing surface roughness. The surface roughness may cause ocular irritation and may be difficult to reduce. 
         [0039]    In various embodiments, a feature  440  at the surface  425  may be created by moving the focal point  415  along the surface  425 . While the focal point  415  moves along the surface  425 , the material at the focal point  415  is damaged. In one example, the focal point  415  is moved relative to the contact lens  405  by moving the modulated beam  135  using the beam steerer. One skilled in the art will recognize that the feature  440  may be any shape or size at the surface  425  and that there may be multiple features  440  at the contact lens  405 . Furthermore, the feature  440  may extend from the surface  425  to the surface  430 . The presence of the feature  440  may modify the characteristics of the contact lens  405  according to some embodiments 
         [0040]    In some embodiments, the material at the feature  440  may be left intact. In other embodiments, the material at the feature  440  may be removed. In one example, the material at the feature  440  may be removed by a chemical process. In another example, the material at the feature  440  may be removed by a plasma etch. When the material at the feature  440  is removed, a void may be left resembling the feature  330 . 
         [0041]      FIG. 5  illustrates a contact lens  505  having exemplary distributions  510 - 520  of features created by the system  100 . The distributions  510 - 520  may each include one or more of the features  330 ,  335 ,  420 ,  440 , and other features discussed herein. In some embodiments, the distributions  510 - 520  may be designed to modify the characteristics of the contact lens  505 . In other embodiments, the distributions  510 - 520  may entirely cover or cover a portion of the contact lens  505 . One skilled in the art would recognize that the distributions  510 - 520  may include any combination of feature sizes, shapes, patterns, compositions, and distribution densities. 
         [0042]      FIG. 6  illustrates, in cross-section, an exemplary contact lens  605  modified by the system  100 . The contact lens  605  includes blind-holes  610 . A single blind-hole may be generally described as a cavity that is open to one surface of the contact lens  605 , but closed to an opposite surface. According to various embodiments, the blind-holes  610  may be created by the ablation process  300  or the damaging process  400  using the system  100 . The blind-holes  610  may be distributed in various ways in the contact lens  605 , including the distributions described in connection with  FIG. 5 . In one embodiment, the blind-holes  610  may be arranged in an alternating fashion such that every other blind-hole  610  is open to a first surface  615  and the rest are open to a second surface  620 . In an alternative embodiment, the blind-holes  610  may be arranged such that they are all open to the same surface (e.g., the first surface  615 ). In one embodiment, the blind-holes  610  may each be approximately cylindrical with the symmetry axis of the cylindrical shape parallel or misaligned to the surface normal. 
         [0043]      FIG. 7  illustrates, in cross-section, an exemplary contact lens  705  modified by the system  100 . The contact lens  705  includes features  710  and  715  that join surfaces  720  and  725 . In one embodiment, the feature  710  may be created by the ablation process  300  using the system  100 . In another embodiment, the feature  710  may be created by the damaging process  400  using the system  100  and subsequently removing the material as discussed herein. The feature  715  may be created by damaging the material using the system  100 , in accordance to various embodiments. One skilled in the art will recognize that the features  710  and  715  may have a variety of shapes. According to various embodiments, the contact lens  705  may include any number or combination of the features  710  and  715  in any distribution (e.g., the distributions described in connection with  FIG. 5 ). 
         [0044]      FIG. 8  illustrates, in cross-section, an exemplary contact lens  805  modified by the system  100 . The contact lens  805  includes features  810  having a complex design. According to various embodiments, the features  810  may be created by the ablation process  300  or the damaging process  400  using the system  100 . The material at the features  810  may be intact or removed as discussed in connection to  FIG. 4 . The features  810  may extend to both, one, or none of surfaces  815  and  820 . One skilled in the art will recognize that the features  810  may have a variety of shapes. The contact lens  805  may include any number or combination of the features  810  in any distribution (e.g., the distributions described in connection with  FIG. 5 ), in accordance with various embodiments. 
         [0045]      FIG. 9  illustrates, in cross-section, an exemplary contact lens  905  modified by the system  100 . The contact lens  905  includes an array  910  of substantially identical features. According to various embodiments, the array  910  may be created by the ablation process  300  or the damaging process  400  using the system  100 . In the example depicted in  FIG. 9 , the array  910  is within the contact lens  905 . In other embodiments, the array  910  may be on a surface of the contact lens  905 . One skilled in the art will recognize that the array  910  may include regular or irregular patterns. Furthermore, the substantially identical features may, at least, include the features described herein, according to various embodiments. 
         [0046]    The above description is illustrative and not restrictive. Many variations of the invention will become apparent to those of skill in the art upon review of this disclosure. The scope of the invention should, therefore, be determined not with reference to the above description, but instead should be determined with reference to the appended claims along with their full scope of equivalents.