Method and apparatus for aligning a mask with the visual axis of an eye
A method is provided for increasing the depth of focus of an eye of a patient. A visual axis of the eye is aligned with an instrument axis of an ophthalmic instrument. The ophthalmic instrument has an aperture through which the patient may look along the instrument axis. A first reference target is imaged on the instrument axis at a first distance with respect to the eye. A second reference target is imaged on the instrument axis with the ophthalmic instrument at a second distance with respect to the eye. The second distance is greater than the first distance. Movement is provided such that the patient's eye is in a position where the images of the first and second reference targets appear to the patient's eye to be aligned. A mask comprising a pin-hole aperture having a mask axis is aligned with the instrument axis such that the mask axis and the instrument axis are substantially collinear. The mask is applied to the eye of the patient while the alignment of the mask axis and the instrument axis is maintained. Maintaining alignment of the mask axis and the instrument axis may be facilitated by capturing an image of the eye.
This application is a continuation of U.S. Application Ser. No. 10/854,032, filed May 26, 2004, which claims priority under 35 U.S.C. §119(e) to U.S. Provisional Application No. 60/479,129, filed on Jun. 17, 2003, the entirety of which is hereby incorporated by reference.
BACKGROUND OF THE INVENTION1. Field of the Invention
This application is directed to masks for improving the depth of focus of an eye of a human patient and methods and apparatuses for applying such masks. More particularly, this application is directed to apparatuses and methods for aligning a mask with the line of sight of an eye and applying the mask to the eye.
2. Description of the Related Art
Presbyopia, or the inability to clearly see objects up close is a common condition that afflicts many adults over the age of 40. Presbyopia diminishes the ability to see or read up close. Near objects appear blurry and out of focus. Presbyopia may be caused by defects in the focusing elements of the eye or the inability (due to aging) of the ciliary muscles to contract and relax and thereby control the shape of the lens in the eye.
The human eye functions by receiving light rays from an object and bending, refracting, and focusing those rays. The primary focusing elements of the human eye are the lens (also referred to as the intraocular lens) and the cornea. Light rays from an object are bent by the cornea, which is located in the anterior part of the eye. The light rays subsequently pass through the intraocular lens and are focused thereby onto the retina, which is the primary light receiving element of the eye. From the retina, the light rays are converted to electrical impulses, which are then transmitted by the optic nerves to the brain.
Ideally, the cornea and lens bend and focus the light rays in such a way that they converge at a single point on the retina. Convergence of the light rays on the retina produces a focused image. However, if the cornea or the lens are not functioning properly, or are irregularly shaped, the images may not converge at a single point on the retina. Similarly, the image may not converge at a single point on the retina if the muscles in the eye can no longer adequately control the lens. This condition is sometimes described as loss of accommodation. In presbyopic patients, for example, the light rays often converge at a point behind the retina. To the patient, the resulting image is out of focus and appears blurry.
Traditionally, vision improvement has been achieved by prescribing eye glasses or contact lenses to the patient. Eye glasses and contact lenses are shaped and curved to help bend light rays and improve focusing of the light rays onto the retina of the patient. However, some vision deficiencies, such as presbyopia, are not adequately addressed by these approaches.
SUMMARY OF THE INVENTIONIn one embodiment, a method is provided for increasing the depth of focus of an eye of a patient. The eye has a visual axis. The visual axis of the eye is aligned with an instrument axis of an ophthalmic instrument. The ophthalmic instrument has an aperture through which the patient may look along the instrument axis. A first reference target is imaged on the instrument axis at a first distance with respect to the eye. A second reference target is imaged on the instrument axis at a second distance with respect to the eye. The second distance is greater than the first distance. Movement is provided such that the patient's eye is in a position where the images of the first and second reference targets appear to the patient's eye to be aligned. A mask comprising a pin-hole aperture having a mask axis is aligned with the instrument axis such that the mask axis and the instrument axis are substantially collinear. The mask is applied to the eye of the patient while the alignment of the mask and the instrument axis is maintained.
In another embodiment, a method for increasing the depth of focus of an eye of a patient is provided. The eye includes a visual axis and a cornea that has an epithelial sheet, a Bowman's membrane, and a stroma. The visual axis of the eye is located using more than one reference target. A mask that includes a pin-hole aperture having a mask axis is aligned with the visual axis of the eye. The mask is applied to the eye while maintaining the alignment of the mask axis and the visual axis.
In another embodiment, a method for correcting vision is provided. A LASIK procedure is performed. The eye is moved until at least two reference targets are aligned. A mask is applied to the eye.
In another embodiment, an apparatus for aligning a mask with a visual axis of an eye of a patient includes an optics housing, a first target, a second target, a lens, and a light source. The optics housing defines an aperture at a first location into which the eye may be directed and an instrument axis. The first target is coupled with the optics housing and is positioned on the instrument axis at a first distance relative to the first location. The second target is coupled with the optics housing and is positioned on the instrument axis at a second distance relative to the first location. The lens is coupled with the optics housing. The second distance is equal to the focal length of the lens. The light source is off-set from the instrument axis and is configured to indicate the location of the visual axis of the eye.
In another embodiment, an apparatus for aligning a mask with a visual axis of an eye of a patient includes a fixture for locating the eye at a first location. The apparatus for aligning also includes a first target, a second target, and a marker. The first target is positioned on an instrument axis at a first distance relative to the first location. The second target is positioned on the instrument axis at a second distance relative to the first location. The marker is configured to indicate the location of the instrument axis.
In another embodiment, a method of treating a patient is provided. A reference point on a cornea is identified. The reference point is marked. A corneal flap is lifted to expose an intracorneal surface. An implant is positioned on the intracorneal surface. The flap is closed to cover at least a portion of the implant.
In another embodiment, a method of treating a patient is provided. A reference point on a cornea is identified. The reference point is marked. A corneal pocket is created to expose an intracorneal surface. An implant is positioned on the intracorneal surface.
In another embodiment, a method of treating a patient is provided. A reference point on a cornea is identified. The reference point is marked. A stromal surface is exposed. An implant is positioned on the stromal surface. At least a portion of the implant is covered.
In one embodiment, a mask configured to be implanted in a cornea of a patient to increase the depth of focus of the patient includes an anterior surface, a posterior surface, and a plurality of holes. The anterior surface is configured to reside adjacent a first corneal layer. The posterior surface is configured to reside adjacent a second corneal layer. The plurality of holes extends at least partially between the anterior surface and the posterior surface. The plurality of holes is configured to substantially eliminate visible diffraction patterns.
In another embodiment, a mask configured to be implanted in a cornea of a patient to increase the depth of focus of the patient is provided. The mask includes a body that has an anterior surface configured to reside adjacent a first corneal layer and a posterior surface configured to reside adjacent a second corneal layer. The body is formed of a substantially opaque material that has a relatively high water content. The body is capable of substantially maintaining natural nutrient flow from the first corneal layer to the second corneal layer. The body being is configured to substantially eliminate diffraction patterns that are visible to the patient.
In another embodiment, a method of making a mask is provided. A body is configured to have an anterior surface capable of residing adjacent a first layer of a cornea of a patient and a posterior surface capable of residing adjacent a second layer of the cornea. A peripheral portion of the body is configured to be substantially opaque to incident light. A central portion of the body is configured to be transparent along an optic axis to substantially all of the incident light. The body is configured with a transport structure capable of substantially maintaining natural nutrient flow from the first layer to the second layer without producing visible diffraction patterns.
In another embodiment, a method of making a mask is provided. A body that has an anterior surface, a posterior surface, an outer periphery, and an inner periphery is provided. The anterior surface is configured to reside adjacent a first layer of a cornea of a patient. The posterior surface is configured to reside adjacent a second layer of the cornea. A plurality of non-uniform locations for forming a plurality of holes between the anterior surface and the posterior surface is generated. A subset of locations among the plurality of locations is modified to maintain a performance characteristic of the mask. A hole is formed in the body at locations corresponding to the subset of locations. The holes are configured to substantially maintain natural nutrient flow from the first layer to the second layer without producing visible diffraction patterns.
BRIEF DESCRIPTION OF THE DRAWINGS
This application is directed to masks for improving the depth of focus of an eye of a patient and methods and apparatuses for applying such masks. The masks generally employ pin-hole vision correction and have nutrient transport structures. The masks may be applied to the eye in any manner and in any location, e.g., as an implant in the cornea (sometimes referred to as a “corneal inlay”). The masks can also be embodied in or combined with lenses and applied in other regions of the eye, e.g., as or in combination with a contact lenses or an intraocular lenses. Apparatuses and methods for applying the masks to the patient generally use the patient's vision to locate the patient's line of sight while the mask is being applied to the eye so that the mask may be properly aligned with the line of sight.
I. Overview of Pin-Hole Vision Correction
A mask that has a pinhole aperture may be used to improve the depth of focus of a human eye. As discussed above, presbyopia is a problem of the human eye that commonly occurs in older human adults wherein the ability to focus becomes limited to inadequate range.
The eye 10 also includes a ring of pigmented tissue known as the iris 22. The iris 22 includes smooth muscle for controlling and regulating the size of an opening 24 in the iris 22, which is known as the pupil. An entrance pupil 26 is seen as the image of the iris 22 viewed through the cornea 12 (See
The eye 10 resides in an eye-socket in the skull and is able to rotate therein about a center of rotation 30.
Turning now to
Turning now to
II. Masks Employing Pin-Hole Correction
The mask 34 preferably has a constant thickness, as discussed below. However, in some embodiments, the thickness of the mask may vary between the inner periphery (near the aperture 38) and the outer periphery.
The annular region 36 is at least partially and preferably completely opaque. The opacity of the annular region 36 prevents light from being transmitted through the mask 32 (as generally shown in
For example, in one embodiment, the material used to make mask 34 may be naturally opaque. Alternatively, the material used to make the mask 34 may be substantially clear, but treated with a dye or other pigmentation agent to render region 36 substantially or completely opaque. In still another example, the surface of the mask 34 may be treated physically or chemically (such as by etching) to alter the refractive and transmissive properties of the mask 34 and make it less transmissive to light.
In still another alternative, the surface of the mask 34 may be treated with a particulate deposited thereon. For example, the surface of the mask 34 may be deposited with particulate of titanium, gold or carbon to provide opacity to the surface of the mask 34. In another alternative, the particulate may be encapsulated within the interior of the mask 34, as generally shown in
Turning to
In another embodiment, the mask may be formed from co-extruded rods made of material having different light transmissive properties. The co-extruded rod may then be sliced to provide disks for a plurality of masks, such as those described herein.
Other embodiments employ different ways of controlling the light transmissivity through a mask. For example, the mask may be a gel-filled disk, as shown in
The material of the mask 34 may be any biocompatible polymeric material. Where a gel is used, the material is suitable for holding a gel. Examples of suitable materials for the mask 34 include the preferred polymethylmethacrylate or other suitable polymers, such as polycarbonates and the like. Of course, as indicated above, for non-gel-filled materials, a preferred material may be a fibrous material, such as a Dacron mesh.
The mask 34 may also be made to include a medicinal fluid, such as an antibiotic that can be selectively released after application, insertion, or implantation of the mask 34 into the eye of the patient. Release of an antibiotic after application, insertion, or implantation provides faster healing of the incision. The mask 34 may also be coated with other desired drugs or antibiotics. For example, it is known that cholesterol deposits can build up on the eye. Accordingly, the mask 34 may be provided with a releasable cholesterol deterring drug. The drug may be coated on the surface of the mask 34 or, in an alternative embodiment, incorporated into the polymeric material (such as PMMA) from which the mask 34 is formed.
Thus, as shown in
Nano-devices or nanites are crystalline structures grown in laboratories. The nanites may be treated such that they are receptive to different stimuli such as light. In accordance with one aspect of the present invention, the nanites can be imparted with energy where, in response to a low light and high light environments, they rotate in the manner described above and generally shown in
Nanoscale devices and systems and their fabrication are described in Smith et al., “Nanofabrication,” Physics Today, February 1990, pp. 24-30 and in Craighead, “Nanoelectromechanical Systems,” Science, Nov. 24, 2000, Vol. 290, pp. 1532-1535, both of which are incorporated by reference herein in their entirety. Tailoring the properties of small-sized particles for optical applications is disclosed in Chen et al. “Diffractive Phase Elements Based on Two-Dimensional Artificial Dielectrics,” Optics. Letters, Jan. 15, 1995, Vol. 20, No. 2, pp. 121-123, also incorporated by reference herein in its entirety.
Masks 34 made in accordance with the present invention may be further modified to include other properties.
The masks described herein may be incorporated into the eye of a patient in different ways. For example, as discussed in more detail below in connection with
When used as a corneal implant, layers of the cornea 12 are peeled away to allow insertion of the mask 34. Typically, the optical surgeon (using a laser) cuts away and peels away a flap of the overlying corneal epithelium. The mask 34 is then inserted and the flap is placed back in its original position where, over time, it grows back and seals the eyeball. In some embodiments, the mask 34 is attached or fixed to the eye 10 by support strands 72 and 74 shown in
In certain circumstances, to accommodate the mask 34, the surgeon may be required to remove additional corneal tissue. Thus, in one embodiment, the surgeon may use a laser to peel away additional layers of the cornea 12 to provide a pocket that will accommodate the mask 34. Application of the mask 34 to the cornea 12 of the eye 10 of a patient is described in greater detail in connection with
Removal of the mask 34 may be achieved by simply making an additional incision in the cornea 12, lifting the flap and removing the mask 34. Alternatively, ablation techniques may be used to completely remove the mask 34.
Further mask details are disclosed in U.S. Pat. No. 4,976,732, issued Dec. 11, 1990 and in U.S. Provisional Application Ser. No. 60/473,824, filed May 28, 2003, both of which are incorporated by reference herein in their entirety.
III. Methods of Applying Pinhole Aperture Devices
The various masks discussed herein can be used to improve the vision of a presbyopic patient as well as patient's with other vision problems. The masks discussed herein can be deployed in combination with a LASIK procedure, to eliminate the effects of abrasions, aberrations, and divots in the cornea. It is also believed that the masks disclosed herein can be used to treat patients suffering from macular degeneration, e.g., by directing light rays to unaffected portions of retina, thereby improving the vision of the patient. Whatever treatment is contemplated, more precise the alignment of the central region of a mask with a pin-hole aperture with the visual axis of the patient is believed to provide greater clinical effect to the patient.
A. Alignment of the Pinhole Aperture with the Patient's Visual Axis
Alignment of the central region of the pinhole aperture 38, in particular, the optical axis 39, of the mask 34 with the visual axis of the eye 10 may be achieved in a variety of ways. As discussed more fully below, such alignment may be achieved by imaging two reference targets at different distances and effecting movement of the patient's eye to a position where the images of the first and second reference targets appear aligned as viewed by the patient's eye. When the patient views the targets as being aligned, the patient's visual axis is located.
In a normal eye, the image of the target 1008 is formed at the retina 16. The fovea 20 (the region of the retina 16 with particularly high resolution) is slightly off-set from the axis of symmetry 1004 of the eye 10. This visual axis 1000 is typically inclined at an angle θ of about six (6) degrees to the axis of symmetry 1004 of the eye 10 for an eye with a centered iris.
The reference target 1016 in
In another embodiment, color is used to indicate when the patient's eye is aligned with the optical axis of the apparatus. For example, a dual color set can be provided. The dual color set may comprise a first region of a first color and a second region of a second color. As discussed above in connection with the dual pattern sets, the patient visual axis is located when the first color and the second color are in a particular position relative to each other. This may cause a desired visual effect to the patient's eye, e.g., when the first region of the first color is aligned with the second region of the second color, the patient may observe a region of a third color. For example, if the first region is colored blue and the second region is colored yellow, the patient will see a region of green. Additional details concerning locating a patient's visual axis or line of sight are contained in U.S. Pat. No. 5,474,548, issued Dec. 12, 1995, incorporated by reference herein in its entirety.
In the illustrated embodiment, the optical system 1206 of the instrument includes a first reference target 1208, a second reference target 1210, and a projection lens 1212. The first and second reference targets 1208, 1210 are imaged by the projection lens 1212 along an instrument axis 1213 of the ophthalmic instrument 1200. In one embodiment, the first reference target 1208 is formed on a first glass reticle 1214 located a first distance 1216 from the lens 1212 and the second target 1210 is formed on a second glass reticle 1218 located a second distance 1220 from the lens 1212. Preferably, the second distance 1220 is equal to the focal length f of the lens 1212, as was discussed in connection with
The optical system 1206 preferably also includes a light source 1222 that marks the visual axis of the patient after the visual axis has been located in the manner described above. In the illustrated embodiment, the light source 1222 is positioned separately from the first and second reference targets 1208, 1210. In one embodiment, the light source 1222 is positioned at a ninety degree angle to the instrument axis 1213 and is configured to direct light toward the axis 1213. In the illustrated embodiment, a beamsplitter plate or cube 1224 is provided between the first and second reference targets 1208, 1210 and the patient to route light rays emitted by the light source 1222 to the eye of the patient. The beamsplitter 1224 is an optical component that reflects light rays from the direction of the light source 1222, but permits the light rays to pass through the beamsplitter along the instrument axis 1213. Thus, light rays form the first and second reference targets 1208, 1210 and from the light source 1222 may be propagated toward the eye of the patient. Other embodiments are also possible. For example, the beamsplitter 1224 could be replaced with a mirror that is movable into and out of the instrument axis 1213 to alternately reflect light from the light source 1222 to the eye or to permit light from the first and second reference targets 1208, 1210 to reach the eye.
The patient locating fixture 1204 includes an elongate spacer 1232 and a contoured locating pad 1234. The contoured locating pad 1234 defines an aperture through which the patient may look along the instrument axis 213. The spacer 1232 is coupled with the optics housing 1202 and extends a distance 1236 between the housing 1202 and the contoured locating pad 1234. In one embodiment, the spacer 1232 defines a lumen 1238 that extends between the contoured locating pads 1234 and the optics housing 1202. In some embodiments, the magnitude of the distance 1236 may be selected to increase the certainty of the location of the patient's visual axis. In some embodiments, it is sufficient that the distance 1236 be a relatively fixed distance.
When the alignment apparatus 1200 is used, the patient's head is brought into contact with the contoured locating pad 1234, which locates the patients eye 10 in the aperture at a fixed distance from the first and second reference targets 1208, 1210. Once the patient's head is positioned in the contoured locating pad 1234, the patient may move the eye 10 as discussed above, to locate the visual axis. After locating the visual axis, the light source 1222 is engaged to emit light toward the eye 10, e.g., as reflected by the beamsplitter 1224.
In the illustrated embodiment, at least some of the light emitted by the light source 1222 is reflected by the beamsplitter 1224 along the instrument axis 1213 toward the patient's eye 10. Because the visual axis of the eye 10 was previously aligned with the instrument axis 1213, the light from the light source 1222 reflected by the beamsplitter 1224 is also aligned with the visual axis of the eye 10.
The reflected light provides a visual marker of the location of the patient's visual axis. The marking function of the light source 1222 is particularly useful in connection with the methods, described below, of applying a mask. Additional embodiments of ophthalmic instruments embodying this technique are described below in connection with
B. Methods of Applying a Mask
Having described a method for properly locating the visual axis of the eye 10 a patient and for visually marking the visual axis, various methods for applying a mask to the eye will be discussed.
In accordance with a still further embodiment of the invention, a mask is surgically implanted into the eye of a patient interested in increasing his or her depth of focus. For example, a patient may suffer from presbyopia, as discussed above. The mask may be a mask as described herein, similar to those described in the prior art, or a mask combining one or more of these properties. Further, the mask may be configured to correct visual aberrations. To aid the surgeon surgically implanting a mask into a patient's eye, the mask may be pre-rolled or folded for ease of implantation.
The mask may be implanted in several locations. For example, the mask may be implanted underneath the cornea's epithelium sheet, beneath the cornea's Bowman membrane, in the top layer of the cornea's stroma, or in the cornea's stroma. When the mask is placed underneath the cornea's epithelium sheet, removal of the mask requires little more than removal of the cornea's epithelium sheet.
In another embodiment, a mask of sufficient thinness, i.e., less than substantially 20 microns, may be placed underneath epithelium sheet 1410. In another embodiment, an optic mark having a thickness less than about 20 microns may be placed beneath Bowman's membrane 1520 without creating a depression in the top layer of the stroma.
In an alternate method for surgically implanting a mask in the eye of a patient, the mask may be threaded into a channel created in the top layer of the stroma. In this method, a curved channeling tool creates a channel in the top layer of the stroma, the channel being in a plane parallel to the surface of the cornea. The channel is formed in a position corresponding to the visual axis of the eye. The channeling tool either pierces the surface of the cornea or, in the alternative, is inserted via a small superficial radial incision. In the alternative, a laser focusing an ablative beam may create the channel in the top layer of the stroma. In this embodiment, the mask may be a single segment with a break, or it may be two or more segments. In any event, the mask in this embodiment is positioned in the channel and is thereby located so that the central axis of the pinhole aperture formed by the mask is substantially collinear with the patient's visual axis to provide the greatest improvement in the patient's depth of focus.
In another alternate method for surgically implanting a mask in the eye of a patient, the mask may be injected into the top layer of the stroma. In this embodiment, an injection tool with a stop penetrates the surface of the cornea to the specified depth. For example, the injection tool may be a ring of needles capable of producing a mask with a single injection. In the alternative, a channel may first be created in the top layer of the stroma in a position corresponding to the visual axis of the patient. Then, the injector tool may inject the mask into the channel. In this embodiment, the mask may be a pigment, or it may be pieces of pigmented material suspended in a bio-compatible medium. The pigment material may be made of a polymer or, in the alternative, made of a suture material. In any event, the mask injected into the channel is thereby positioned so that the central axis of the pinhole aperture formed by the pigment material is substantially collinear with the visual axis of the patient.
In another method for surgically implanting a mask in the eye of a patient, the mask may be placed beneath the corneal flap created during keratectomy, when the outermost 20% of the cornea is hinged open. As with the implantation methods discussed above, a mask placed beneath the corneal flap created during keratectomy should be substantially aligned with the patient's visual axis, as discussed above, for greatest effect.
In another method for surgically implanting a mask in the eye of a patient, the mask may be aligned with the patient's visual axis and placed in a pocket created in the cornea's stroma.
Further details concerning alignment apparatuses are disclosed in U.S. Provisional Application Ser. No. 60/479,129, filed Jun. 17, 2003, incorporated by reference herein in its entirety.
IV. Further Surgical Systems for Aligning a Pinhole Aperture with a Patient's Eye
In one embodiment, the surgical system 2000 includes a surgical viewing device 2004 and an alignment device 2008. In one embodiment, the surgical viewing device 2004 includes a surgical microscope. The surgical viewing device 2004 may be any device or combination of devices that enables a surgeon to visualize the surgical site with sufficient clarity or that enhances the surgeon's visualization of the surgical site. A surgeon also may elect to use the alignment device 2004 without a viewing device. As discussed more fully below in connection another embodiment of a surgical system shown in
In one embodiment, the alignment device 2008 includes an alignment module 2020, a marking module 2024, and an image capture module 2028. As discussed below, in another embodiment, the marking module 2024 is eliminated. Where the marking module 2024 is eliminated, one or more of its functions may be performed by the image capture module 2028. In another embodiment, the image capture module 2028 is eliminated. The alignment device 2004 preferably also has a control device 2032 that directs one or more components of the alignment device 2004. As discussed more fully below, the control device 2032 includes a computer 2036 and signal lines 2040a, 2040b, and a trigger 2042 in one embodiment.
The alignment module 2020 includes components that enable a patient to align a feature related to the patient's eye, vision, or sense of sight with an instrument axis, e.g., an axis of the alignment device 2008. In one embodiment, the alignment module 2020 includes a plurality of targets (e.g., two targets) that are located on the instrument axis. In the illustrated embodiment, the alignment module 2020 includes a first target 2056 and a second target 2060. The alignment module 2020 may be employed to align the patient's line-of-sight with an axis 2052 that extends perpendicular to the faces of the targets 2056, 2060.
Although the alignment device 2008 could be configured such that the patient is positioned relative thereto so that the eye is positioned along the axis 2052, it may be more convenient to position the patient such that an eye 2064 of the patient is not on the axis 2052. For example, as shown in
In this arrangement, the alignment device 2008 is configured such that the patient viewing axis 2072 is at about a ninety degree angle with respect to the instrument axis 2052. In this embodiment, a path 2076 optically connecting the targets 2056, 2060 with the patient's eye 2064 extends partially along the axis 2052 and partially along the patient viewing axis 2072. The optical path 2076 defines the path along which the images of the targets 2056, 2060 are cast when the alignment device 2008 is configured such that the patient's eye 2064 is not on the axis 2052.
Positioning the patient off of the axis 2052, may be facilitated by one or more components that redirect light traveling along or parallel to the axis 2052. In one embodiment, the alignment device 2008 includes a beamsplitter 2080 located on the axis 2052 to direct along the patient viewing axis 2072 light rays coming toward the beamsplitter 2080 from the direction of the targets 2056, 2060. In this embodiment, at least a portion of the optical path 2076 is defined from the patient's eye 2064 to the beamsplitter 2080 and from the beamsplitter 2080 to the first and second targets 2056, 2060. Although the alignment device 2008 is configured to enable the patient viewing axis 2072 to be at about a ninety degree angle with respect to the axis 2052, other angles are possible and may be employed as desired. The arrangement of
In one embodiment, the first target 2056 is on the axis 2052 and on the optical path 2076 between the second target 2060 and the patient's eye 2064. More particularly, light rays that are directed from the second target 2060 intersect the first target 2056 and are thereafter directed toward the beamsplitter 2080. As discussed more fully below, the first and second targets 2056, 2060 are configured to project a suitable pattern toward the patient's eye 2064. The patient interacts with the projected images of the first and second targets 2056, 2060 to align the line-of-sight (or other unique anatomical feature) of the patient's eye 2064 or of the patient's sense of vision with an axis of the instrument, such as the axis 2052, the viewing axis 2072, or the optical path 2076.
The first and second targets 2056, 2060 may take any suitable form. The targets 2056, 2060 may be similar to those hereinbefore described. The targets 2056, 2060 may be formed on separate reticles or as part of a single alignment target. In one embodiment, at least one of the first and second targets 2056, 2060 includes a glass reticle with a pattern formed thereon. The pattern on the first target 2056 and the pattern on the second target 2060 may be linear patterns that are combined to form a third linear pattern when the patient's line-of-sight is aligned with the axis 2052 or optical path 2076.
Although shown as separate elements, the first and second targets 2056, 2060 may be formed on a alignment target.
The first and second targets 2056, 2060 (or the first and second patterns 2085, 2086) may be made visible to the patient's eye 2064 in any suitable manner. For example, a target illuminator 2090 may be provided to make the targets 2056, 2060 visible to the eye 2064. In one embodiment, the target illuminator 2090 is a source of radiant energy, such as a light source. The light source can be any suitable light source, such as an incandescent light, a fluorescent light, one or more light emitting diodes, or any other source of light to illuminate the targets 2056, 2060.
As discussed more fully below, the alignment module 2020 also may include one or more optic elements, such as lenses, that relatively sharply focus the images projected from the first and second targets 2056, 2060 to present sharp images to the patient's eye 2064. In such arrangements, the focal length of the optic element or system of optical elements may be located at any suitable location, e.g., at the first or second targets 2056, 2060, between the first and second targets 2056, 2060 in front of the first target 2056, or behind the second target 2060. The focal length is the distance from a location (e.g., the location of an optic element) to the plane at which the optic element focuses the target images projected from the first and second target 2056, 2060.
While the target illuminator 2090 and the first and second targets 2056, 2060 project the images of the targets to the patient's eye 2064, the patient may interact with those images to align a feature of the patient's eye 2064 with an axis of the alignment device 2008. In the embodiment illustrated by
Techniques for aligning the line of sight of the patient's eye 2064 with the instrument axis have been discussed above. In the context of the embodiment of
Although aligning the eye may be sufficient to provide relatively precise placement of the masks described herein, one or both of the marking module 2024 and the image capture module 2028 may be included to assist the surgeon in placing a mask after the eye 2064 has been aligned. At least one of the marking module 2024 and the image capture module 2028 may be used to correlate the line-of-sight of the patient's eye 2064, which is not otherwise visible, with a visual cue, such as a visible physical feature of the patient's eye, a marker projected onto the eye or an image of the eye, or a virtual image of a marker visible to the surgeon, or any combination of the foregoing. As is discussed in more detail below, the virtual image may be an image that is directed toward the surgeon's eye that appears from the surgeon's point of view to be on the eye 2064 at a pre-selected location.
In one embodiment, the marking module 2024 is configured to produce an image, sometimes referred to herein as a “marking image”, that is visible to the surgeon and that is assists the surgeon in placing a mask or performing another surgical procedure after the line of sight of the eye 2064 has been located. The marking module 2024 of the alignment device 2008 shown includes a marking target 2120 and a marking target illuminator 2124. The marking target illuminator 2124 preferably is a source of light, such as any of those discussed above in connection with the target illuminator 2090.
A beamsplitter 2140, to be discussed below in connection with the image capture module 2028, is positioned on the marking axis 2128 in the embodiment of
As discussed more fully below, projecting the marking image onto the patient's eye 2064 may assist the surgeon in accurately placing a mask. For example, the surgeon may be assisted in that the location of line-of-sight of the patient's eye (or some other generally invisible feature of the eye 2064) is correlated with a visible feature of the eye, such as the iris or other anatomical feature. In one technique, the marking image is a substantially circular ring that has a diameter that is greater than the size of the inner periphery of the iris under surgical conditions (e.g., the prevailing light and the state of dilation of the patient's eye 2064). In another technique, the marking image is a substantially circular ring that has a diameter that is less than the size of the outer periphery of the iris under surgical conditions (e.g., light and dilation of the eye 2064). In another technique, the marking image is a substantially circular ring that has a size that is correlated to another feature of the eye 2064, e.g., the limbus of the eye.
In one embodiment of the system 2000, a marking module is provided that includes a secondary marking module. The secondary marking module is not routed through the optics of associated with the alignment device 2008. Rather, the secondary marking module is coupled with the alignment device 2008. In one embodiment, the secondary marking module includes a source of radiant energy, e.g., a laser or light source similar to any of these discussed herein. The source of radiant energy is configured to direct a plurality of spots (e.g., two, three, four, or more than four spots) onto the patient's eye 2064. The spots preferably are small, bright spots. The spots indicate positions on the eye 2064 that correlate with a feature of a mask, such as an edge of a mask, when the mask is in the correct position with respect to the line-of-sight of the eye 2064. The spots can be aligned with the projected marking target such that they hit at a selected location on the projected marking target (e.g., circumferentially spaced locations on the inner edge, on the outer edge, or on both the inner and outer edges). Thus, the marking module may give a visual cue as to the proper positioning of a mask that is correlated to the location of the line-of-sight without passing through the optics of the alignment device. The visual cue of the secondary marking module may be coordinated with the marking image of the marking module 2024 in some embodiments.
In some techniques, it may be beneficial to increase the visibility of a visual cue generated for the benefit of the surgeon (e.g., the reflection of the image of the marking target 2120) on the eye 2064. In some cases, this is due to the generally poor reflection of marking images off of the cornea. Where reflection of the marking image off of the cornea is poor, the reflection of the image may be quite dim. In addition, the cornea is an off-center aspherical structure, so the corneal reflection (purkinje images) may be offset from the location of the intersection of the visual axis and the corneal surface as viewed by the surgeon.
One technique for increasing the visibility of a visual cue involves applying a substance to the eye that can react with the projected image of the marking target 2120. For example, a dye, such as fluorescein dye, can be applied to the surface of the eye. Then the marking target illuminator 2124 may be activated to cause an image of the marking target 2120 to be projected onto the eye, as discussed above. In one embodiment, the marking target illuminator 2124 is configured to project light from all or a discrete portion of the visible spectrum of electromagnetic radiant energy, e.g., the wavelengths corresponding to blue light, to project the image of the marking target 2120 onto the eye 2064. The projected image interacts with the dye and causes the image of the marking target 2120 to be illuminated on the surface of the cornea. The presence of the dye greatly increases the visibility of the image of the marking target. For example, where the marking target 2120 is a ring, a bright ring will be visible to the surgeon because the light causes the dye to fluoresce. This technique substantially eliminates errors in placement of a mask due to the presence of the purkinje images and may generally increase the brightness of the image of the marking target 2120.
Another technique for increasing the visibility of a visual cue on the eye involves applying a visual cue enhancing device to at least a portion of the anterior surface of the eye 2064. For example, in one technique, a drape is placed over the cornea. The drape may have any suitable configuration. For example, the drape may be a relatively thin structure that will substantially conform to the anterior structure of the eye. The drape may be formed in a manner similar to the formation of a conventional contact lens. In one technique, the drape is a contact lens. The visual cue enhancing device preferably has suitable reflecting properties. In one embodiment, the visual cue enhancing device diffusely reflects the light projecting the image of the marking target 2120 onto the cornea. In one embodiment, the visual cue enhancing device is configured to interact with a discrete portion of the visible spectrum of electromagnetic radiant energy, e.g., the wavelengths thereof corresponding to blue light.
As discussed above the alignment device 2008 shown in
The camera 2200 can be any suitable camera. One type of camera that can be used is a charge-coupled device camera, referred to herein as a CCD camera. One type of CCD camera incorporates a silicon chip, the surface of which includes light-sensitive pixels. When light, e.g., a photon or light particle, hits a pixel, an electric charge is registered at the pixels that can be detected. Images of sufficient resolution can be generated with a large array of sensitive pixels. As discussed more fully below, one advantageous embodiment provides precise alignment of a selected pixel (e.g., one in the exact geometric center of the display device 2204) with the axis 2052. When such alignment is provided, the marking module may not be needed to align a mask with the line-of-sight of the eye 2064.
As discussed above, an image captured by the camera 2200 aids the surgeon attempting to align a mask, such as any of the masks described herein, with the eye 2064. In one arrangement, the image capture module 2028 is configured to capture an image of one or more physical attributes of the eye 2064, the location of which may be adequately correlated to the line-of-sight of the eye 2064. For example, the image of the patient's iris may be directed along the patient viewing axis 2072 to the beamsplitter 2080 as indicated by the arrow 2148. As mentioned above, a side of the beamsplitter 2080 that faces the beamsplitter 2080 is reflective to light transmitted from the eye 2064. Thus, at least a substantial portion of the light conveying the image of the iris of the eye 2064 is reflected by the beamsplitter 2080 and is conveyed along the axis 2052 toward the beamsplitter 2102, as indicated by the arrow 2106. As discussed above, the surface of the beamsplitter 2102 facing the beamsplitter 2080 is reflective to light. Thus, substantially all of the light conveying the image of the iris is reflected by the beamsplitter 2102 and is conveyed along the marking axis 2128 toward the beamsplitter 2140, as indicated by the arrow 2144. The surface of the beamsplitter 2140 facing the beamsplitter 2102 and the camera 2200 is reflective to light. Thus, substantially all of the light conveying the image of the iris is reflected along an image capture axis 2212 that extends between the beamsplitter 2140 and the camera 2200. The light is conveyed along an image capture axis 2212 as indicated by an arrow 2216.
The image captured by the camera 2200 is conveyed to the computer 2036 by way of a signal line 2040a. The computer 2036 processes the signal in a suitable manner and generates signals to be conveyed along a signal line 2040b to the display device 2204. Any suitable signal line and computer or other signal processing device can be used to convey signals from the camera 2200 to the display device 2204. The signal lines 2040a, 2040b need not be physical lines. For example, any suitable wireless technology may be used in combination with or in place of physical lines or wires.
The capturing of the image by the camera 2200 may be triggered in any suitable way. For example, the trigger 2042 may be configured to be manually actuated. In one embodiment, the trigger 2042 is configured to be actuated by the patient when his or her eye 2064 is aligned (e.g., when the targets 2056, 2060 are aligned, as discussed above). By enabling the patient to trigger the capturing of the image of the eye 2064 by the image capture module 2028, the likelihood of the eye 2064 moving prior to the capturing of the image is greatly reduced. In another embodiment, another person participating in the procedure may be permitted to trigger the capturing of the image, e.g., on the patient's cue. In another embodiment, the control device 2032 may be configured to automatically capture the image of the patient's eye 2064 based on a predetermined criteria.
The display device 2204 is configured to be illuminated to direct an image along the axis 2052 toward the beamsplitter 2080 as indicated by an arrow 2208. The surface of the beamsplitter 2080 that faces the display device 2204 preferably is reflective to light directed from the location of the beamsplitter 2080. Thus, the image on the display 2052 is reflected by the beamsplitter 2080 toward an eye 2212 of the surgeon as indicated by an arrow 2216. The beamsplitter 2080 preferably is transparent from the perspective of the surgeon's eye 2212. Thus, the surgeon may simultaneously view the patient's eye 2064 and the image on the display device 2204 in one embodiment. In one embodiment where both the marking module 2024 and the image capture module 2028 are present, the marking image may be projected at the same time that an image is displayed on the display device 2204. The marking image and the image on the display will appear to both be on the patient's eye. In one arrangement, they have the same configuration (e.g., size and shape) and therefore overlap. This can reinforce the image from the perspective of the surgeon, further increasing the visibility of the visual cue provided by the marking image.
The display device 2204 is located at a distance 2220 from the beamsplitter 2080. The patient is located a distance 2224 from the axis 2052. Preferably the distance 2220 is about equal to the distance 2224. Thus, both the display device 2204 and the patient's eye 2064 are at the focal length of the surgical viewing device 2004. This assures that the image generated by the display device 2204 is in focus at the same time that the patient's eye is in focus.
In one embodiment, the system 2000 is configured to track movement of the patient's eye 2064 during the procedure. In one configuration, the trigger 2042 is actuated by the patient when the eye 2064 is aligned with an axis of the alignment device 2008. Although a mask is implanted shortly thereafter, the patient's eye is not constrained and may thereafter move to some extent. In order to correct for such movement, the image capture module 2028 may be configured to respond to such movements by moving the image formed on the display device 2204. For example, a ring may be formed on the display device 2204 that is similar to those discussed above in connection with the marking target 2120. The beamsplitter 2080 enables the surgeon to see the ring visually overlaid on the patient's eye 2064. The image capture module 2028 compares the real-time position of the patient's eye 2064 with the image of the eye captured when the trigger 2042 is actuated. Differences in the real-time position and the position captured by the camera 2200 are determined. The position of the ring is moved an amount corresponding to the differences in position. As a result, from the perspective of the surgeon, movements of the ring and the eye correspond and the ring continues to indicate the correct position to place a mask.
As discussed above, several variations of the system 2000 are contemplated. A first variation is substantially identical to the embodiment shown in
In one implementation of the first variation, the marking module 2024 is configured to display the marking image to the surgeon's eye 2212 but not to the patient's eye 2064. This may be provided by positioning the marking target 2120 approximately in the location of the display device 2204. The marking image may be generated and presented to the surgeon in any suitable manner. For example, the marking target 2120 and marking target illuminator 2124 may be repositioned so that they project the image of the marking target 2120 as indicated by the arrows 2208, 2216. The marking target 2120 and the marking target illuminator 2124 may be replaced by a unitary display, such as an LCD display. This implementation of the first variation is advantageous in that the marking image is visible to the surgeon but is not visible to the patient. The patient is freed from having to respond to or being subject to the marking image. This can increase alignment performance by increasing patient comfort and decreasing distractions, thereby enabling the patient to remain still during the procedure.
In another implementation of the first variation, a dual marking image is presented to the eye 2212 of the surgeon. In one form, this implementation has a marking module 2024 similar to that shown in
In a second variation, the marking module 2024 is eliminated. In this embodiment, the image capture module 2028 provides a visual cue for the surgeon to assist in the placement of a mask. In particular, an image can be displayed on the display device 2204, as discussed above. The image can be generated in response to the patient actuating the trigger 2042. In one technique, the patient actuates the trigger when the targets 2056, 2060 appear aligned, as discussed above. In this variation, care should be taken to determine the position of the display device 2204 in the alignment device because the image formed on the display device 2204 is to give the surgeon a visual cue indicating the location of the line-of-sight of the patient. In one embodiment, the display device 2204 is carefully coupled with the alignment module so that the axis 2052 extends through a known portion (e.g., a known pixel) thereof. Because the precise location of the axis 2052 on the display device 2204 is known, the relationship of the image formed thereon to the line-of-sight of the patient is known.
The portion of the surgical system 2400 is shown from the surgeon's viewpoint in
The fixture 2408 may take any suitable form. In the illustrated embodiment, the fixture 2408 includes a clamp 2412, an elevation adjustment mechanism 2416, and suitable members to interconnect the clamp 2408 and the mechanism 2416. In the embodiment of
The fixture 2408 preferably also is configured to suspend the alignment device 2404 at an elevation below the clamp 2412. In the illustrated embodiment, a bracket 2440 is coupled with the clamp 2412, which is an L-shaped bracket in the illustrated embodiment with a portion of the L extending downward from the clamp 2412.
Preferably the fixture 2408 is also configured to enable the alignment device 2404 to be positioned at a selected elevation within a range of elevations beneath the clamp 2412. The elevation of the alignment device 2404 may be easily and quickly adjusted by manipulating a suitable mechanism. For example, manual actuation may be employed by providing a knob 2460 coupled with a rack-and-pinion gear coupling 2464. Of course the rack-and-pinion gear coupling 2464 can be actuated by another manual device that is more remote, such as by a foot pedal or trigger or by an automated device.
The alignment module 2504 is similar to the alignment module 2020 except as set forth below. The alignment module 2504 includes a housing 2520 that extends between a first end 2524 and a second end 2528. The first end 2524 of the housing 2520 is coupled with the image routing module 2512 and interacts with the image routing module 2512 in a manner described below. The housing 2520 includes a rigid body 2532 that preferably is hollow. An axis 2536 extends within the hollow portion of the housing 2520 between the first and second ends 2524, 2528. In the illustrated embodiment, the second end 2528 of the housing 2520 is enclosed by an end plate 2540.
The housing 2520 is configured to protect a variety of components that are positioned in the hollow spaced defined therein. In one embodiment, a target illuminator 2560 is positioned inside the housing 2520 near the second end 2528 thereof. A power cable 2564 (or other electrical conveyance) that extends from the end plate 2540 electrically connects the target illuminator 2560 to a power source. The target illuminator 2560 could also be triggered and powered by a wireless connection. In one arrangement, the power source forms a portion of the illuminator control device 2500 to which the power cable 2564 is connected. Power may be from any suitable power source, e.g., from a battery or electrical outlet of suitable voltage.
As discussed above, the illuminator control device 2500 enables the surgeon (or other person assisting in a procedure) to control the amount of energy supplied to the target illuminator 2560 in the alignment module 2504. In one embodiment, the illuminator control device 2500 has a brightness control so that the brightness of the target illumination 2560 can be adjusted. The brightness control may be actuated in a suitable manner, such as by a brightness control knob 2568. The brightness control may take any other suitable form to provide manual analog (e.g., continuous) adjustment of the amount of energy applied to the target illuminator 2560 or to provide manual digital (e.g., discrete) adjustment of the amount of energy applied to the target illuminator 2560. In some embodiments, the brightness control may be adjustable automatically, e.g., under computer control. The illuminator control device 2500 may also have an on-off switch 2572 configured to selectively apply and cut off power to the target illuminator 2560. The on-off switch 2572 may be operated manually, automatically, or in a partially manual and partially automatic mode. The brightness control and on-off switch could be controlled wirelessly in another embodiment.
Also located in the housing 2520 are a first target 2592, a second target 2596, and a lens 2600. As discussed above, the first and second targets 2592, 2596 are configured to present a composite image to the patient's eye such that the patient may align the line-of-sight of the eye with an axis (e.g., the axis 2536) of the alignment module 2504. The first and second targets 2592, 2596 are similar to the targets discussed above. In particular alignment target 2081, which includes two targets on opposite ends of a single component, may be positioned within the housing 2520.
The lens 2600 may be any suitable lens. Preferably the lens 2600 is configured to sharply focus one or both of the images of the first and second targets 2592, 2596 in a manner similar to the focus of the targets 2056, 2060, discussed above.
In one embodiment, the alignment module 2504 is configured such that the position of the first and second targets 2592, 2596 within the housing 2520 can be adjusted. The adjustability of the first and second targets 2592, 2596 may be provided with any suitable arrangement.
In one embodiment, the target adjustment device 2612 includes a support member 2616 that extends along at least a portion of the housing 2520 between the first end 2524 and the second end 2528. In one embodiment, the support member 2616 is coupled with the end plate 2540 and with the image routing module 2512. In one embodiment, the target adjustment device 2612 includes a lens fixture 2620 that is coupled with the lens 2600 and a target fixture 2624 that is coupled with the first and second targets 2592, 2596. In another embodiment, each of the first and second targets 2592, 2596 is coupled with a separate target fixture so that the targets may be individually positioned and adjusted. The lens 2600 may be adjustable as shown, or in a fixed position. Movement of the lens and the targets 2592, 2596 enable the patterns on the targets 2592, 2596 to be brought into focus from the patient's point of view.
In one arrangement, the support member 2616 is a threaded rod and each of the first and second target fixtures 2620, 2624 has a corresponding threaded through hole to receive the threaded support member 2616. Preferably an adjustment device, such as a knob 2628 is coupled with the threaded support member 2616 so that the support member 2616 may be rotated. The knob 2628 may be knurled to make it easier to grasp and rotate. Rotation of the support member 2616 causes the first and second target fixtures 2620, 2624 to translate on the support member 2616 along the outside of the housing 2520. The movement of the first and second target fixtures 2620, 2624 provides a corresponding movement of the first and second targets 2592, 2596 within the housing 2520.
In one embodiment a quick release mechanism 2640 is provided to enable the first and second target fixtures 2620, 2624 selectively to clamp and to release the support member 2616. The quick release mechanism 2640 can be a spring loaded clamp that causes the through holes formed in the first and second target fixtures 2620, 2624 to open to create a gap through which the support member 2616 can pass. When the first and second target fixtures 2620, 2624 are removed from the support member 2616, the can be quickly moved to another position on the support member 2616. After rapid repositioning, fine positioning of the first and second target fixtures 2620, 2624 may be achieved with by turning the support member 2616.
As discussed above, the alignment device 2404 also includes a marking module 2508 that is similar to the marking module 2024 described above, except as set forth below. The marking module includes a housing 2642 that is generally rigid and that defines a hollow space within the housing. The housing 2642 includes a first end 2644 that is coupled with the image routing module 2512 and a second end 2648 that is closed by an end plate 2652. In one embodiment, the housing 2642 includes a first portion 2656 and a second portion 2660. The first and second portions 2656, 2660 preferably are configured to be disengaged from each other so that components located in the hollow space defined in the housing 2642 to be accessed. Such rapid access facilitates servicing and reconfiguring of the components located in the housing 2642. The first portion 2656 extends between the first end 2644 and a midpoint of the housing 2642. The second portion 2660 extends between the first portion 2656 and the second end 2648 of the housing 2642. In one embodiment, the first portion 2656 has a male member with external threads and the second portion 2660 has a female member with internal thread such that the first and second portions 2656, 2660 may be engaged with and disengaged from each other by way of the threads.
As discussed above, the housing 2642 provides a space in which one or more components may be positioned. In the illustrated embodiment, the housing 2642 encloses a marking target illuminator 2680 and a marking target 2684.
The marking target illuminator 2680 may be a suitable source of radiant energy, e.g., a light source, such as an incandescent light, a fluorescent light, a light-emitting diode, or other source of radiant energy. As with the target illuminators discussed above, the marking target illuminator 2680 may include or be coupled with suitable optical components to process the light generated thereby in a useful manner, e.g., by providing one or more filters to modify the light, e.g., by allowing a subset of the spectrum of light energy emitted by the light source (e.g., one or more bands of the electromagnetic spectrum) to be transmitted toward the marking target 2684.
In the illustrated embodiment, the marking target illuminator 2680 is located near the end plate 2652. A power cable 2688 (or other electrical conveyance) that extends from the end plate 2652 electrically connects the marking target illuminator 2680 to a power source. In one arrangement, the power source forms a portion of the illuminator control device 2500 to which the power cable 2688 is connected. Power may be from any suitable power source, e.g., from a battery or electrical outlet of suitable voltage.
As discussed above, the illuminator control device 2500 enables the surgeon (or other person assisting in a procedure) to control the amount of energy supplied to the target illuminator 2680 in the marking module 2508. The illuminator control device 2500 has a brightness control so that the brightness of the marking target illumination 2680 can be adjusted. The brightness control may be actuated in a suitable manner, such as by a brightness control knob 2692. The brightness control may be similar to that discussed above in connection with the brightness control of the target illuminator 2560. The illuminator control device 2500 may also have an on-off switch 2696 configured to selectively apply and cut off power to the marking target illuminator 2680. The on-off switch 2696 may be operated manually, automatically, or in a partially manual and partially automatic mode. Any of the power supply, the brightness control, and the on-off switch may be implemented wirelessly in various other embodiments.
In one embodiment, the marking target 2684 is a reticle, e.g., made of glass, with an annular shape formed thereon. For example, the annular shape formed on the marking target 2684 may be a substantially clear annulus surrounded by opaque regions. In this configuration, light directed toward the marking target 2684 interacts with the marking target 2684 to produce and annular image. In another embodiment, the marking target 2684 may be a substantially clear reticle with an opaque shape, such as an opaque annular shape. The annular image is directed into the image routing device 2684, as discussed further below. The marking target 2684 may be housed in a fixture 2718 that is removable, e.g., when the first portion 2656 and the second portion 2660 of the housing 2642 are decoupled. The first portion 2656 of the housing 2642 is configured to engage the fixture 2718 to relatively precisely position the marking target 2684 with respect to an axis of the housing 2642.
The image routing module 2512 also may include a third optic device 2740 and a frame 2744 coupled with the housing 2720. The frame 2744 is configured to position and orient the third optic device 2740 with respect to the housing 2720. In one embodiment, the third optic device 2740 is a beamsplitter and the frame 2744 holds the third optic device 2740 at about a forty-five degree angle with respect to the axis 2520. In this position, the third optic device 2740 interacts with light reflected by the first surface 2736 of the second optic device 2732. The third optic device 2740 may operate in a manner similar to the beamsplitter 2080 of
The second optic device 2732 is configured to be transparent to substantially all of the light conveying an image along the axis 2536 such that the image conveyed along the axis 2536 may be directed to the third optic device 2740 and thereafter to an eye of a surgeon, as discussed about in connection with
Although the image routing device is shown with first, second, and third optic devices 2728, 2732, 2740 to route light conveying images in a particular manner, one skilled in the art will recognize that the image routing device 2512 could have more or fewer optic devices that route the image, depending on the desired geometry and compactness of the alignment device 2404.
A variation of the alignment device 2404 provides a marking module with a secondary marking module not routed through the optics of the alignment device 2404. In one embodiment, the secondary marking module includes a source of radiant energy, e.g., a laser or other light source. The source of radiant energy is configured to direct a plurality of spots (e.g., three, four, or more than four spots) onto the patient's eye. The spots indicate positions on the eye that correlate with an edge of a mask when the mask is in the correct position with respect to the line-of-sight of the eye 2064. The spots can be aligned with the projected marking target such that they hit at a selected location on the projected marking target (e.g., circumferentially spaced locations on the inner edge, on the outer edge, or on both the inner and outer edges). At least a portion of the secondary marking module is coupled with the frame 2744 in one embodiment. A laser of the secondary marking module could be attached to the frame 2744 and suspended therefrom, oriented downward toward the patient's eye. As discussed above, this arrangement provides a secondary device for marking the proper location of a mask with respect to a patient's line of sight after the line of sight has been identified.
Although various exemplary embodiments of apparatuses and methods for aligning a patient's line-of-sight with an axis of an instrument in connection with the application of a mask have been discussed hereinabove, it should be apparent to those skilled in the art that various changes and modifications can be made which will achieve at least some of the advantages of the invention without departing from, the true scope of the invention. These and other obvious modifications are intended to be covered by the appended claims.
V. Masks Configured to Reduce the Visibility of Diffraction Patterns
Many of the foregoing masks can be used to improve the depth of focus of a patient. Various additional mask embodiments are discussed below. Some of the embodiments described below include nutrient transport structures that are configured to enhance or maintain nutrient flow between adjacent tissues by facilitating transport of nutrients across the mask. The nutrient transport structures of some of the embodiments described below are configured to at least substantially prevent nutrient depletion in adjacent tissues. The nutrient transport structures can decrease negative effects due to the presence of the mask in adjacent corneal layers when the mask is implanted in the cornea, increasing the longevity of the masks. The inventors have discovered that certain arrangements of nutrient transport structures generate diffraction patterns that interfere with the vision improving effect of the masks described herein. Accordingly, certain masks are described herein that include nutrient transport structures that do not generate diffraction patterns or otherwise interfere with the vision enhancing effects of the mask embodiments.
In one embodiment, the mask 3000 includes a body 3004 that has an anterior surface 3008 and a posterior surface 3012. In one embodiment, the body 3004 is capable of substantially maintaining natural nutrient flow between the first corneal layer and the second corneal layer. In one embodiment, the material is selected to maintain at least about ninety-six percent of the natural flow of at least one nutrient (e.g., glucose) between a first corneal layer (e.g., the layer 1410) and a second corneal layer (e.g., the layer 1430). The body 3004 may be formed of any suitable material, including at least one of an open cell foam material, an expanded solid material, and a substantially opaque material. In one embodiment, the material used to form the body 3004 has relatively high water content.
In one embodiment, the mask 3000 includes and a nutrient transport structure 3016. The nutrient transport structure 3016 may comprise a plurality of holes 3020. The holes 3020 are shown on only a portion of the mask 3000, but the holes 3020 preferably are located throughout the body 3004 in one embodiment. In one embodiment, the holes 3020 are arranged in a hex pattern, which is illustrated by a plurality of locations 3020′ in
Preferably the mask 3000 is symmetrical, e.g., symmetrical about a mask axis 3036. In one embodiment, the outer periphery 3024 of the mask 3000 is circular and has a diameter of less than about 6 mm in one embodiment. In another embodiment, the mask is circular and has a diameter in the range of 4 to 6 mm. In another embodiment, the mask 3000 is circular and has a diameter of less than 4 mm. The outer periphery 3024 has a diameter of about 3.8 mm in another embodiment. In some embodiments, masks that are asymmetrical or that are not symmetrical about a mask axis provide benefits, such as enabling a mask to be located or maintained in a selected position with respect to the anatomy of the eye.
The body 3004 of the mask 3000 may be configured to coupled with a particular anatomical region of the eye. The body 3004 of the mask 3000 may be configured to conform to the native anatomy of the region of the eye in which it is to be applied. For example, where the mask 3000 is to be coupled with an ocular structure that has curvature, the body 3004 may be provided with an amount of curvature along the mask axis 3036 that corresponds to the anatomical curvature. For example, one environment in which the mask 3000 may be deployed is within the cornea of the eye of a patient. The cornea has an amount of curvature that varies from person to person about a substantially constant mean value within an identifiable group, e.g., adults. When applying the mask 3000 within the cornea, at least one of the anterior and posterior surfaces 3008, 3012 of the mask 3000 may be provided with an amount of curvature corresponding to that of the layers of the cornea between which the mask 3000 is applied.
In some embodiments, the mask 3000 has a desired amount of optical power. Optical power may be provided by configuring the at least one of the anterior and posterior surfaces 3008, 3012 with curvature. In one embodiment, the anterior and posterior surfaces 3008, 3012 are provided with different amounts of curvature. In this embodiment, the mask 3000 has varying thickness from the outer periphery 3024 to the aperture 3028.
In one embodiment, one of the anterior surface 3008 and the posterior surface 3012 of the body 3004 is substantially planar. In one planar embodiment, very little or no uniform curvature can be measured across the planar surface. In another embodiment, both of the anterior and posterior surfaces 3008, 3012 are substantially planar. In one embodiment, the body 3004 of the mask 3000 has a thickness 3038 of between about 5 micron and about 10 micron. In one embodiment, the thickness 3038 of the mask 3000 is about 5 micron. In another embodiment, the thickness 3038 of the mask 3000 is about 8 micron. In another embodiment, the thickness 3038 of the mask 3000 is about 10 micron.
Thinner masks generally are more suitable for applications wherein the mask 3000 is implanted at a relatively shallow location in (e.g., close to the anterior surface of) the cornea. In thinner masks, the body 3004 may be sufficiently flexible such that it can take on the curvature of the structures with which it is coupled without negatively affecting the optical performance of the mask 3000. In one application, the mask 3000 is configured to be implanted about 5 um beneath the anterior surface of the cornea. In another application, the mask 3000 is configured to be implanted about 65 um beneath the anterior surface of the cornea. In another application, the mask 3000 is configured to be implanted about 125 um beneath the anterior surface of the cornea. Further details regarding implanting the mask 3000 in the cornea are discussed above in connection with
A substantially planar mask has several advantages over a non-planar mask. For example, a substantially planar mask can be fabricated more easily than one that has to be formed to a particular curvature. In particular, the process steps involved in inducing curvature in the mask 3000 can be eliminated. Also, a substantially planar mask may be more amenable to use on a wider distribution of the patient population (or among different sub-groups of a broader patient population) because the substantially planar mask uses the curvature of each patient's cornea to induce the appropriate amount of curvature in the body 3004.
In some embodiments, the mask 3000 is configured specifically for the manner and location of coupling with the eye. In particular, the mask 3000 may be larger if applied over the eye as a contact lens or may be smaller if applied within the eye posterior of the cornea, e.g., proximate a surface of the lens of the eye. As discussed above, the thickness 3038 of the body 3004 of the mask 3000 may be varied based on where the mask 3000 is implanted. For implantation at deeper levels within the cornea, a thicker mask may be advantageous. Thicker masks are advantageous in some applications. For example, they are generally easier to handle, and therefore are easier to fabricate and to implant. Thicker masks may benefit more from having a preformed curvature than thinner masks. A thicker mask could be configured to have little or no curvature prior to implantation if it is configured to conform to the curvature of the native anatomy when applied.
The aperture 3028 is configured to transmit substantially all incident light along the mask axis 3036. The non-transmissive portion 3032 surrounds at least a portion of the aperture 3028 and substantially prevents transmission of incident light thereon. As discussed in connection with the above masks, the aperture 3028 may be a through-hole in the body 3004 or a substantially light transmissive (e.g., transparent) portion thereof. The aperture 3028 of the mask 3000 generally is defined within the outer periphery 3024 of the mask 3000. The aperture 3028 may take any of suitable configurations, such as those described above in connection with
In one embodiment, the aperture 3028 is substantially circular and is substantially centered in the mask 3000. The size of the aperture 3028 may be any size that is effective to increase the depth of focus of an eye of a patient suffering from presbyopia. For example, the aperture 3028 can be circular, having a diameter of less than about 2.2 mm in one embodiment. In another embodiment, the diameter of the aperture is between about 1.8 mm and about 2.2 mm. In another embodiment, the aperture 3028 is circular and has a diameter of about 1.8 mm or less.
The non-transmissive portion 3032 is configured to prevent transmission of radiant energy through the mask 3000. For example, in one embodiment, the non-transmissive portion 3032 prevents transmission of substantially all of at least a portion of the spectrum of the incident radiant energy. In one embodiment, the non-transmissive portion 3032 is configured to prevent transmission of substantially all visible light, e.g., radiant energy in the electromagnetic spectrum that is visible to the human eye. The non-transmissive portion 3032 may substantially prevent transmission of radiant energy outside the range visible to humans in some embodiments.
As discussed above in connection with
In one embodiment, the non-transmissive portion 3032 prevents transmission of about 90 percent of incident light. In another embodiment, the non-transmissive portion 3032 prevents transmission of about 92 percent of all incident light. The non-transmissive portion 3032 of the mask 3000 may be configured to be opaque to prevent the transmission of light. As used herein the term “opaque” is intended to be a broad term meaning capable of preventing the transmission of radiant energy, e.g., light energy, and also covers structures and arrangements that absorb or otherwise block all or less than all or at least a substantial portion of the light. In one embodiment, at least a portion of the body 3004 is configured to be opaque to more than 99 percent of the light incident thereon.
As discussed above, the non-transmissive portion 3032 may be configured to prevent transmission of light without absorbing the incident light. For example, the mask 3000 could be made reflective or could be made to interact with the light in a more complex manner, as discussed in U.S. Pat. No. 6,554,424, issued Apr. 29, 2003, which is hereby incorporated by reference herein in its entirety.
As discussed above, the mask 3000 also has a nutrient transport structure that in some embodiments comprises the plurality of holes 3020. The presence of the plurality of holes 3020 (or other transport structure) may affect the transmission of light through the non-transmissive portion 3032 by potentially allowing more light to pass through the mask 3000. In one embodiment, the non-transmissive portion 3032 is configured to absorb about 99 percent or more of the incident light from passing through the mask 3000 without holes 3020 being present. The presence of the plurality of holes 3020 allows more light to pass through the non-transmissive portion 3032 such that only about 92 percent of the light incident on the non-transmissive portion 3032 is prevented from passing through the non-transmissive portion 3032. The holes 3020 may reduce the benefit of the aperture 3028 on the depth of focus of the eye by allowing more light to pass through the non-transmissive portion to the retina.
Reduction in the depth of focus benefit of the aperture 3028 due to the holes 3020 is balanced by the nutrient transmission benefits of the holes 3020. In one embodiment, the transport structure 3016 (e.g., the holes 3020) is capable of substantially maintaining natural nutrient flow from a first corneal layer (i.e., one that is adjacent to the anterior surface 3008 of the mask 3000) to the second corneal layer (i.e., one that is adjacent to the posterior surface 3012 of the mask 3000). The plurality of holes 3020 are configured to enable nutrients to pass through the mask 3000 between the anterior surface 3008 and the posterior surface 3012. As discussed above, the holes 3020 of the mask 3000 shown in
The holes 3020 of
The transport structure 3016 is configured to maintain the transport of one or more nutrients across the mask 3000. The transport structure 3016 of the mask 3000 provides sufficient flow of one or more nutrients across the mask 3000 to prevent depletion of nutrients at least at one of the first and second corneal layers (e.g., the layers 1410 and 1430). One nutrient of particular importance to the viability of the adjacent corneal layers is glucose. The transport structure 3016 of the mask 3000 provides sufficient flow of glucose across the mask 3000 between the first and second corneal layers to prevent glucose depletion that would harm the adjacent corneal tissue. Thus, the mask 3000 is capable of substantially maintaining nutrient flow (e.g., glucose flow) between adjacent corneal layers. In one embodiment, the nutrient transport structure 3016 is configured to prevent depletion of more than about 4 percent of glucose (or other biological substance) in adjacent tissue of at least one of the first corneal layer and the second corneal layer.
The holes 3020 may be configured to maintain the transport of nutrients across the mask 3000. In one embodiment, the holes 3020 are formed with a diameter of about 0.015 mm or more. In another embodiment, the holes have a diameter of about 0.020 mm. In another embodiment, the holes have a diameter of about 0.025 mm. In another embodiment, the holes 3020 have a diameter in the range of about 0.020 mm to about 0.029 mm. The number of holes in the plurality of holes 3020 is selected such that the sum of the surface areas of the hole entrances 3060 of all the holes 3000 comprises about 5 percent or more of surface area of the anterior surface 3008 of the mask 3000. In another embodiment, the number of holes 3020 is selected such that the sum of the surface areas of the hole exits 3064 of all the holes 3020 comprises about 5 percent or more of surface area of the posterior surface 3012 of the mask 3000. In another embodiment, the number of holes 3020 is selected such that the sum of the surface areas of the hole exits 3064 of all the holes 3020 comprises about 5 percent or more of surface area of the posterior surface 3012 of the mask 3012 and the sum of the surface areas of the hole entrances 3060 of all the holes 3020 comprises about 5 percent or more of surface area of the anterior surface 3008 of the mask 3000.
Each of the holes 3020 may have a relatively constant cross-sectional area. In one embodiment, the cross-sectional shape of each of the holes 3020 is substantially circular. Each of the holes 3020 may comprise a cylinder extending between the anterior surface 3008 and the posterior surface 3012.
The relative position of the holes 3020 is of interest in some embodiments. As discussed above, the holes 3020 of the mask 3000 are hex-packed, e.g., arranged in a hex pattern. In particular, in this embodiment, each of the holes 3020 is separated from the adjacent holes 3020 by a substantially constant distance, sometimes referred to herein as a hole pitch 3072. In one embodiment, the hole pitch 3072 is about 0.062 mm.
The embodiment of
The inventors have discovered a variety of techniques that produce advantageous arrangements of a transport structure such that diffraction patterns and other deleterious visual effects do not substantially inhibit other visual benefits of a mask. In one embodiment, where diffraction effects would be observable, the nutrient transport structure is arranged to spread the diffracted light out uniformly across the image to eliminate observable spots. In another embodiment, the nutrient transport structure employs a pattern that substantially eliminates diffraction patterns or pushes the patterns to the periphery of the image.
Other embodiments may be provided that vary at least one aspect, including one or more of the foregoing aspects, of a plurality of holes to reduce the tendency of the holes to produce visible diffraction patterns or patterns that otherwise reduce the vision improvement that may be provided by a mask with an aperture, such as any of those described above. For example, in one embodiment, the hole size, shape, and orientation of at least a substantial number of the holes may be varied randomly or may be otherwise non-uniform.
The outer peripheral region 4205 may extend from an outer periphery 4224 of the mask 4200 to a selected outer circumference 4226 of the mask 4200. The selected outer circumference 4225 of the mask 4200 is located a selected radial distance from the outer periphery 4224 of the mask 4200. In one embodiment, the selected outer circumference 4225 of the mask 4200 is located about 0.05 mm from the outer periphery 4224 of the mask 4200.
The inner peripheral region 4206 may extend from an inner location, e.g., an inner periphery 4226 adjacent an aperture 4228 of the mask 4200 to a selected inner circumference 4227 of the mask 4200. The selected inner circumference 4227 of the mask 4200 is located a selected radial distance from the inner periphery 4226 of the mask 4200. In one embodiment, the selected inner circumference 4227 of the mask 4200 is located about 0.05 mm from the inner periphery 4226.
The mask 4200 may be the product of a process that involves random selection of a plurality of locations and formation of holes on the mask 4200 corresponding to the locations. As discussed further below, the method can also involve determining whether the selected locations satisfy one or more criteria. For example, one criterion prohibits all, at least a majority, or at least a substantial portion of the holes from being formed at locations that correspond to the inner or outer peripheral regions 4205, 4206. Another criterion prohibits all, at least a majority, or at least a substantial portion of the holes 4220 from being formed too close to each other. For example, such a criterion could be used to assure that a wall thickness, e.g., the shortest distance between adjacent holes, is not less than a predetermined amount. In one embodiment, the wall thickness is prevented from being less than about 20 microns.
In a variation of the embodiment of
In one embodiment, each of the holes 4320 has a hole entrance 4360 and a hole exit 4364. Each of the holes 4320 extends along a transport axis 4366. The transport axis 4366 is formed to substantially prevent propagation of light from the anterior surface 4308 to the posterior surface 4312 through the holes 4320. In one embodiment, at least a substantial number of the holes 4320 have a size to the transport axis 4366 that is less than a thickness of the mask 4300. In another embodiment, at least a substantial number of the holes 4320 have a longest dimension of a perimeter at least at one of the anterior or posterior surfaces 4308, 4312 (e.g., a facet) that is less than a thickness of the mask 4300. In some embodiments, the transport axis 4366 is formed at an angle with respect to a mask axis 4336 that substantially prevents propagation of light from the anterior surface 4308 to the posterior surface 4312 through the hole 4320. In another embodiment, the transport axis 4366 of one or more holes 4320 is formed at an angle with respect to the mask axis 4336 that is large enough to prevent the projection of most of the hole entrance 4360 from overlapping the hole exit 4364.
In one embodiment, the hole 4320 is circular in cross-section and has a diameter between about 0.5 micron and about 8 micron and the transport axis 4366 is between 5 and 85 degrees. The length of each of the holes 4320 (e.g., the distance between the anterior surface 4308 and the posterior surface 4312) is between about 8 and about 92 micron. In another embodiment, the diameter of the holes 4320 is about 5 micron and the transport angle is about 40 degrees or more. As the length of the holes 4320 increases it may be desirable to include additional holes 4320. In some cases, additional holes 4320 counteract the tendency of longer holes to reduce the amount of nutrient flow through the mask 4300.
In one embodiment, at least one of the holes 4420 extends along a non-linear path that substantially prevents propagation of light from the anterior surface to the posterior surface through the at least one hole. In one embodiment, the mask 4400 includes a first hole portion 4420a that extends along a first transport axis 4466a, the second mask layer 4414 includes a second hole portion 4420b extending along a second transport axis 4466b, and the third mask layer 4415 includes a third hole portion 4420c extending along a third transport axis 4466c. The first, second, and third transport axes 4466a, 4466b, 4466c preferably are not collinear. In one embodiment, the first and second transport axes 4466a, 4466b are parallel but are off-set by a first selected amount. In one embodiment, the second and third transport axes 4466b, 4466c are parallel but are off-set by a second selected amount. In the illustrated embodiment, each of the transport axes 44466a, 4466b, 4466c are off-set by one-half of the width of the hole portions 4420a, 4420b, 4420c. Thus, the inner-most edge of the hole portion 4420a is spaced from the axis 4336 by a distance that is equal to or greater than the distance of the outer-most edge of the hole portion 4420b from the axis 4336. This spacing substantially prevents light from passing through the holes 4420 from the anterior surface 4408 to the posterior surface 4412.
In one embodiment, the first and second amounts are selected to substantially prevent the transmission of light therethrough. The first and second amounts of off-set may be achieved in any suitable fashion. One technique for forming the hole portions 4420a, 4420b, 4420c with the desired off-set is to provide a layered structure. As discussed above, the mask 4400 may include the first layer 4410, the second layer 4414, and the third layer 4415.
In any of the foregoing mask embodiments, the body of the mask may be formed of a material selected to provide adequate nutrient transport and to substantially prevent negative optic effects, such as diffraction, as discussed above. In various embodiments, the masks are formed of an open cell foam material. In another embodiment, the masks are formed of an expanded solid material.
As discussed above in connection with
In a first step of one technique, a plurality of locations 4020′ is generated. The locations 4020′ are a series of coordinates that may comprise a non-uniform pattern or a regular pattern. The locations 4020′ may be randomly generated or may be related by a mathematical relationship (e.g., separated by a fixed spacing or by an amount that can be mathematically defined). In one embodiment, the locations are selected to be separated by a constant pitch or spacing and may be hex packed.
In a second step, a subset of the locations among the plurality of locations 4020′ is modified to maintain a performance characteristic of the mask. The performance characteristic may be any performance characteristic of the mask. For example, the performance characteristic may relate to the structural integrity of the mask. Where the plurality of locations 4020′ is selected at random, the process of modifying the subset of locations may make the resulting pattern of holes in the mask a “pseudo-random” pattern.
Where a hex packed pattern of locations (such as the locations 3020′ of
In one technique, an outer peripheral region is defined that extends between the outer periphery of the mask and a selected radial distance of about 0.05 mm from the outer periphery. In another embodiment, an inner peripheral region is defined that extends between an aperture of the mask and a selected radial distance of about 0.05 mm from the aperture. In another embodiment, an outer peripheral region is defined that extends between the outer periphery of the mask and a selected radial distance and an inner peripheral region is defined that extends between the aperture of the mask and a selected radial distance from the aperture. In one technique, the subset of location is modified by excluding those locations that would correspond to holes formed in the inner peripheral region or the outer peripheral region. By excluding locations in at least one of the outer peripheral region and the inner peripheral region, the strength of the mask in these regions is increased. Several benefits are provided by stronger inner and outer peripheral regions. For example, the mask may be easier to handle during manufacturing or when being applied to a patient without causing damage to the mask.
In another embodiment, the subset of locations is modified by comparing the separation of the holes with minimum and or maximum limits. For example, it may be desirable to assure that no two locations are closer than a minimum value. In some embodiments this is important to assure that the wall thickness, which corresponds to the separation between adjacent holes, is no less than a minimum amount. As discussed above, the minimum value of separation is about 20 microns in one embodiment, thereby providing a wall thickness of no less than about 20 microns.
In another embodiment, the subset of locations is modified and/or the pattern of location is augmented to maintain an optical characteristic of the mask. For example, the optical characteristic may be opacity and the subset of locations may be modified to maintain the opacity of a non-transmissive portion of a mask. In another embodiment, the subset of locations may be modified by equalizing the density of holes in a first region of the body compared with the density of holes in a second region of the body. For example, the locations corresponding to the first and second regions of the non-transmissive portion of the mask may be identified. In one embodiment, the first region and the second region are arcuate regions (e.g., wedges) of substantially equal area. A first areal density of locations (e.g., locations per square inch) is calculated for the locations corresponding to the first region and a second areal density of locations is calculated for the location corresponding to the second region. In one embodiment, at least one location is added to either the first or the second region based on the comparison of the first and second areal densities. In another embodiment, at least one location is removed based on the comparison of the first and second areal densities.
The subset of locations may be modified to maintain nutrient transport of the mask. In one embodiment, the subset of location is modified to maintain glucose transport.
In a third step, a hole is formed in a body of a mask at locations corresponding to the pattern of locations as modified, augmented, or modified and augmented. The holes are configured to substantially maintain natural nutrient flow from the first layer to the second layer without producing visible diffraction patterns.
VI. Further Methods of Treating a Patient
As discussed above in, various techniques are particularly suited for treating a patient by applying masks such as those disclosed herein to an eye. For example, in some embodiments, the surgical system 2000 of
In one method, a patient is treated by placing an implant 5000 in a cornea 5004. A corneal flap 5008 is lifted to expose a surface in the cornea 5004 (e.g., an intracorneal surface). Any suitable tool or technique may be used to lift the corneal flap 5008 to expose a surface in the cornea 5004. For example, a blade (e.g., a microkeratome), a laser or an electrosurgical tool could be used to form a corneal flap. A reference point 5012 on the cornea 5004 is identified. The reference point 5012 thereafter is marked in one technique, as discussed further below. The implant 5000 is positioned on the intracorneal surface. In one embodiment, the flap 5008 is then closed to cover at least a portion of the implant 5000.
The surface of the cornea that is exposed is a stromal surface in one technique. The stromal surface may be on the corneal flap 5008 or on an exposed surface from which the corneal flap 5008 is removed.
The reference point 5012 may be identified in any suitable manner. For example, the alignment devices and methods described above may be used to identify the reference point 5012. In one technique, identifying the reference point 5012 involves illuminating a light spot (e.g., a spot of light formed by all or a discrete portion of radiant energy corresponding to visible light, e.g., red light). As discussed above, the identifying of a reference point may further include placing liquid (e.g., a fluorescein dye or other dye) on the intracorneal surface. Preferably, identifying the reference point 5012 involves alignment using any of the techniques described herein.
As discussed above, various techniques may be used to mark an identified reference point. In one technique the reference point is marked by applying a dye to the cornea or otherwise spreading a material with known reflective properties onto the cornea. As discussed above, the dye may be a substance that interacts with radiant energy to increase the visibility of a marking target or other visual cue. The reference point may be marked by a dye with any suitable tool. The tool is configured so that it bites into a corneal layer, e.g., an anterior layer of the epithelium, and delivers a thin ink line into the corneal layer in one embodiment. The tool may be made sharp to bite into the epithelium. In one application, the tool is configured to deliver the dye as discussed above upon being lightly pressed against the eye. This arrangement is advantageous in that it does not form a larger impression in the eye. In another technique, the reference point may be marked by making an impression (e.g., a physical depression) on a surface of the cornea with or without additional delivery of a dye. In another technique, the reference point may be marked by illuminating a light or other source of radiant energy, e.g., a marking target illuminator and projecting that light onto the cornea (e.g., by projecting a marking target).
Any of the foregoing techniques for marking a reference point may be combined with techniques that make a mark that indicates the location of an axis of the eye, e.g., the visual axis or line-of-sight of the eye. In one technique, a mark indicates the approximate intersection of the visual axis and a surface of the cornea. In another technique, a mark is made approximately radially symmetrically disposed about the intersection of the visual axis and a surface of the cornea.
As discussed above, some techniques involve making a mark on an intracorneal surface. The mark may be made by any suitable technique. In one technique a mark is made by pressing an implement against the instracorneal surface. The implement may form a depression that has a size and shape that facilitate placement of a mask. For example, in one form the implement is configured to form a circular ring (e.g., a thin line of dye, or a physical depression, or both) with a diameter that is slightly larger than the outer diameter of a mask to be implanted. The circular ring can be formed to have a diameter between about 4 mm and about 5 mm. The intracorneal surface is on the corneal flap 5008 in one technique. In another technique, the intracorneal surface is on an exposed surface of the cornea from which the flap was removed. This exposed surface is sometimes referred to as a tissue bed.
In another technique, the corneal flap 5008 is lifted and thereafter is laid on an adjacent surface 5016 of the cornea 5004. In another technique, the corneal flap 5008 is laid on a removable support 5020, such as a sponge. In one technique, the removable support has a surface 5024 that is configured to maintain the native curvature of the corneal flap 5008.
In one technique, the corneal flap 5008 is closed by returning the corneal flap 5008 to the cornea 5004 with the implant 5000 on the corneal flap 5008. In another technique, the corneal flap 5008 is closed by returning the corneal flap 5008 to the cornea 5004 over the implant 5000, which previously was placed on the tissue bed (the exposed intracorneal surface).
When the intracorneal surface is a stromal surface, the implant 5000 is placed on the stromal surface. At least a portion of the implant 5000 is covered. In some techniques, the implant 5000 is covered by returning a flap with the implant 5000 thereon to the cornea 5004 to cover the stromal surface. In one technique, the stromal surface is exposed by lifting an epithelial layer to expose stroma. In another technique, the stromal surface is exposed by removing an epithelial layer to expose stroma. In some techniques, an additional step of replacing the epithelial layer to at least partially cover the implant 5000 is performed.
After the flap 5008 is closed to cover at least a portion of the implant 5000, the implant 5000 may be repositioned to some extent in some applications. In one technique, pressure is applied to the implant 5000 to move the implant into alignment with the reference point 5012. The pressure may be applied to the anterior surface of the cornea 5004 proximate an edge of the implant 5000 (e.g., directly above, above and outside a projection of the outer periphery of the implant 5000, or above and inside a projection of the outer periphery of the implant 5000). This may cause the implant to move slightly away from the edge proximate which pressure is applied. In another technique, pressure is applied directly to the implant. The implant 5000 may be repositioned in this manner if the reference point 5012 was marked on the flap 5008 or if the reference point 5012 was marked on the tissue bed.
After the implant 5100 is positioned in the pocket 5108, the implant 5100 may be repositioned to some extent in some applications. In one technique, pressure is applied to the implant 5100 to move the implant into alignment with the reference point 5112. The pressure may be applied to the anterior surface of the cornea 5104 proximate an edge of the implant 5100 (e.g., directly above, above and outside a projection of the outer periphery of the implant 5100, or above and inside a projection of the outer periphery of the implant 5100). This may cause the implant 5100 to move slightly away from the edge at which pressure is applied., In another technique, pressure is applied directly to the implant 5100.
Although this invention has been disclosed in the context of certain preferred embodiments and examples, it will be understood by those skilled in the art that the present invention extends beyond the specifically disclosed embodiments to other alternative embodiments and/or uses of the invention and obvious modifications and equivalents thereof. In addition, while a number of variations of the invention have been shown and described in detail, other modifications, which are within the scope of this invention, will be readily apparent to those of skill in the art based upon this disclosure. It is also contemplated that various combinations or sub-combinations of the specific features and aspects of the embodiments may be made and still fall within the scope of the invention. Accordingly, it should be understood that various features and aspects of the disclosed embodiments can be combine with or substituted for one another in order to form varying modes of the disclosed invention. Thus, it is intended that the scope of the present invention herein disclosed should not be limited by the particular disclosed embodiments described above, but should be determined only by a fair reading of the claims that follow.
Claims
1.-4. (canceled)
5. A method of treating a patient, comprising the steps of:
- identifying a reference point on a cornea;
- marking the reference point;
- lifting a corneal flap to expose an intracorneal surface;
- positioning an implant on the intracorneal surface; and
- closing the flap to cover at least a portion of the implant.
6. A method of treating a patient as in claim 5, wherein the marking step comprises marking a dye on the cornea.
7. A method of treating a patient as in claim 5, wherein the marking step comprises making an impression on the cornea.
8. (canceled)
9. A method of treating a patient as in claim 5, wherein the marking step comprises illuminating a light on the cornea.
10. A method of treating a patient as in claim 5, wherein the marking step comprises making a mark indicative of the location of the visual axis of the eye.
11. A method of treating a patient as in claim 10, wherein the marking step comprises making a mark approximately at the intersection of the visual axis and a surface of the cornea.
12. A method of treating a patient as in claim 10, wherein the marking step comprises making a mark approximately radially symmetrically disposed about the intersection of the visual axis and a surface of the cornea.
13. A method of treating a patient as in claim 5, wherein the intracorneal surface is on the flap.
14. A method of treating a patient as in claim 5, wherein the intracorneal surface is on an exposed surface of the cornea from which the flap was removed.
15. A method of treating a patient as in claim 14, further comprising applying pressure to the implant to move the implant into alignment with the reference point.
16. A method of treating a patient as in claim 13, wherein the closing the flap step comprises returning the flap with the implant thereon to the cornea.
17. A method of treating a patient as in claim 16, further comprising applying pressure to the implant to move the implant into alignment with the reference point.
18. A method of treating a patient as in claim 5, additionally comprising the step of laying the corneal flap on an adjacent surface of the cornea.
19. A method of treating a patient as in claim 5, additionally comprising the step of laying the corneal flap on a removable support.
20. (canceled)
21. A method of treating a patient as in claim 19, wherein the support comprises a surface which is configured to maintain the curvature of the flap.
22. A method of treating a patient as in claim 5, wherein the identifying step comprises illuminating a light spot on the intracorneal surface.
23. (canceled)
24. A method of treating a patient as in claim 23, wherein the identifying step additionally comprises placing a liquid on the intracorneal surface.
25.-36. (canceled)
37. A method of treating a patient, comprising the steps of:
- identifying a reference point on a cornea;
- marking the reference point;
- exposing a stromal surface;
- positioning an implant on the stromal surface; and
- covering at least a portion of the implant.
38. A method of treating a patient as in claim 37, wherein the exposing a stromal surface step comprises lifting an epithelial layer to expose stroma.
39.-48. (canceled)
49. A method of treating a patient as in claim 37, wherein exposing a stromal surface comprises lifting a corneal flap and wherein the stromal surface is on the corneal flap.
50. (canceled)
51. A method of treating a patient as in claim 37, wherein exposing a stromal surface comprises lifting a corneal flap and wherein the stromal surface is on an exposed surface of the cornea from which the flap was removed
52.-54. (canceled)
55. A method of treating a patient as in claim 37, additionally comprising the step of laying a corneal flap on a removable support.
56.-60. (canceled)
Type: Application
Filed: May 3, 2006
Publication Date: Nov 30, 2006
Inventors: Thomas Silvestrini (Alamo, CA), Bruce Christie (Upland, CA), Kevin Hahnen (Center Ossipee, NH), Carl Knopp (Livermore, CA)
Application Number: 11/417,526
International Classification: A61B 13/00 (20060101);
