Method of making an ocular implant

A method is provided for making a mask configured to improve the depth of focus of an eye of a patient. A substrate is provided with a mask forming feature. The mask forming feature comprises an annular surface that has a curved profile that corresponds to the curvature of a corneal layer of the eye. A release layer is formed on the annular surface. A mask layer of a biocompatible metal is formed above the release layer. The mask layer is separated from the substrate.

BACKGROUND OF THE INVENTION

1. 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 making such masks. More particularly, this application is directed to methods that exploit processes that are amenable to large batch processing of biocompatible and highly opaque materials.

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 INVENTION

In one embodiment, a method is provided for making a mask configured to improve the depth of focus of an eye of a patient. A substrate is provided with a mask forming feature. The mask forming feature comprises an annular surface that extends between an inner periphery and an outer periphery. The annular surface is centered on a central axis of the mask forming feature. The annular surface has a curved profile between the inner periphery and the outer periphery that corresponds to the curvature of a corneal layer of the eye. A release layer is formed on the annular surface. A mask layer of a biocompatible metal is formed such that the release layer is between the mask layer and the substrate. The mask layer is separated from the substrate.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

This application is directed to masks for improving the depth of focus of an eye of a patient and methods and apparatuses for making such masks. The masks generally employ pin-hole vision correction and have nutrient transport structures in some embodiments. 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 contact lenses or intraocular lenses. In some applications, discussed further below, the masks are formed of a stable material, e.g., one that can be implanted permanently. Apparatuses and methods for making the masks preferably are capable of producing masks with relatively precise dimensions. Some techniques useful for batch processing include vapor deposition, thin film sputtering and others depending upon the desired design and process parameters.

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.FIGS. 1-6illustrate how presbyopia interferes with the normal function of the eye and how a mask with a pinhole aperture mitigates the problem.

FIG. 1shows the human eye, andFIG. 2is a side view of the eye10. The eye10includes a cornea12and an intraocular lens14posterior to the cornea12. The cornea12is a first focusing element of the eye10. The intraocular lens14is a second focusing element of the eye10. The eye10also includes a retina16, which lines the interior of the rear surface of the eye10. The retina16includes the receptor cells which are primarily responsible for the sense of vision. The retina16includes a highly sensitive region, known as the macula, where signals are received and transmitted to the visual centers of the brain via the optic nerve18. The retina16also includes a point with particularly high sensitivity20, known as the fovea. As discussed in more detail in connection withFIG. 8, the fovea20is slightly offset from the axis of symmetry of the eye10.

The eye10also includes a ring of pigmented tissue known as the iris22. The iris22includes smooth muscle for controlling and regulating the size of an opening24in the iris22, which is known as the pupil. An entrance pupil26is seen as the image of the iris22viewed through the cornea12(SeeFIG. 7). A central point of the entrance pupil28is illustrated inFIG. 7and will be discussed further below.

The eye10resides in an eye-socket in the skull and is able to rotate therein about a center of rotation30.

FIG. 3shows the transmission of light through the eye10of a presbyotic patient. Due to either an aberration in the cornea12or the intraocular lens14, or loss of muscle control, light rays32entering the eye10and passing through the cornea12and the intraocular lens14are refracted in such a way that the light rays32do not converge at a single focal point on the retina16.FIG. 3illustrates that in a presbyotic patient, the light rays32often converge at a point behind the retina16. As a result, the patient experiences blurred vision.

Turning now toFIG. 4, there is shown the light transmission through the eye10to which a mask34has been applied. The mask34can be made by any suitable apparatus or method. Some advantageous methods form the mask34of a material that is at least partially opaque and very stable in the normal environment in which the mask34is deployed. For example, it is desired that the mask34be able to survive many years of exposure to ultraviolet (UV) light. Thus, in some embodiments, the mask is made of a UV stable material. A variety of UV stable materials can be used to form the mask34. Preferably the UV stable material has a high degree of biocompatibility because, as discussed below, the mask34is implanted in the eye10in some techniques. Some specific examples of methods of making the mask34are discussed below in connection withFIGS. 67a-67dand with variations of such processes.

The mask34is shown implanted in the cornea12inFIG. 4. However, as discussed below, it will be understood that the mask34can be, in various modes of application, implanted in the cornea12(as shown), used as a contact lens placed over the cornea12, incorporated in the intraocular lens14(including the patient's original lens or an implanted lens), or otherwise positioned on or in the eye10. In the illustrated embodiment, the light rays32that pass through the mask34, the cornea12, and the lens14converge at a single focal point on the retina16. The light rays32that would not converge at the single point on retina16are blocked by the mask34. As discussed below, it is desirable to position the mask34on the eye10so that the light rays32that pass through the mask34converge at the fovea20.

Turning now toFIG. 6, there is shown one embodiment of the mask34. As seen, the mask34preferably includes an annular region36surrounding a pinhole opening or aperture38substantially centrally located on the mask34. The pinhole aperture38is generally located around a central axis39, referred to herein as the optical axis of the mask34. The pinhole aperture38preferably is in the shape of a circle. It has been reported that a circular aperture, such as the aperture38may, in some patients, produce a so-called “halo effect” where the patient perceives a shimmering image around the object being viewed. Accordingly, it may be desirable to provide an aperture38in a shape that diminishes, reduces, or completely eliminates the so-called “halo effect.”

FIGS. 7-42illustrate a variety of embodiments of masks that can improve the vision of a patient with presbyopia. The masks described in connection withFIG. 7-42are similar to the mask34, except as set forth below. Accordingly, the masks described in connection withFIGS. 7-42can be used and applied to the eye10of a patient in a similar fashion to the mask34. Also, like the mask34, the masks7-42can be formed by the processes disclosed in connection withFIGS. 67a-67dand with variations of such processes.

FIG. 7shows an embodiment of a mask34athat includes an aperture38aformed in the shape of a hexagon.FIG. 8shows another embodiment of a mask34bthat includes an aperture38bformed in the shape of an octagon.FIG. 9shows another embodiment of a mask34cthat includes an aperture38cformed in the shape of an oval, whileFIG. 10shows another embodiment of a mask34dthat includes an aperture38dformed in the shape of a pointed oval.FIG. 11shows another embodiment of a mask34ewherein the aperture38eis formed in the shape of a star or starburst.

FIGS. 12-14illustrate further embodiments that have tear-drop shaped apertures.FIG. 12shows a mask34fthat has a tear-drop shaped aperture38fthat is located above the true center of the mask34f.FIG. 13shows a mask34gthat has a tear-drop shaped aperture38gthat is substantially centered in the mask34g.FIG. 14shows a mask34hthat has a tear-drop shaped aperture38hthat is below the true center of the mask34h.FIGS. 12-14illustrate that the position of aperture can be tailored, e.g., centered or off-center, to provide different effects. For example, an aperture that is located below the true center of a mask generally will allow more light to enter the eye because the upper portion of the aperture34will not be covered by the eyelid of the patient. Conversely, where the aperture is located above the true center of the mask, the aperture may be partially covered by the eyelid. Thus, the above-center aperture may permit less light to enter the eye.

FIG. 15shows an embodiment of a mask34ithat includes an aperture38iformed in the shape of a square.FIG. 16shows an embodiment of a mask34jthat has a kidney-shaped aperture38j. It will be appreciated that the apertures shown inFIGS. 7-16are merely exemplary of non-circular apertures. Other shapes and arrangements may also be provided and are within the scope of the present invention.

The mask34preferably has a constant thickness, as discussed below. However, in some embodiments, the thickness of the mask may vary between the inner periphery (near the aperture38) and the outer periphery.FIG. 17shows a mask34kthat has a gradually decreasing thickness from the inner periphery to the outer periphery.FIG. 18shows a mask341that has a gradually increasing thickness from the inner periphery to the outer periphery. Other cross-sectional profiles are also possible.

The annular region36is at least partially and preferably completely opaque. The opacity of the annular region36prevents light from being transmitted through the mask32(as generally shown inFIG. 4). Opacity of the annular region36may be achieved in any of several different ways.

For example, in one embodiment, the material used to make mask34may be naturally opaque. Alternatively, the material used to make the mask34may be substantially clear, but treated with a dye or other pigmentation agent to render region36substantially or completely opaque. In still another example, the surface of the mask34may be treated physically or chemically (such as by etching) to alter the refractive and transmissive properties of the mask34and make it less transmissive to light.

In still another alternative, the surface of the mask34may be treated with a particulate deposited thereon. For example, the surface of the mask34may be deposited with particulate of titanium, gold or carbon to provide opacity to the surface of the mask34. In another alternative, the particulate may be encapsulated within the interior of the mask34, as generally shown inFIG. 19. Finally, the mask34may be patterned to provide areas of varying light transmissivity, as generally shown inFIGS. 24-33, which are discussed in detail below.

Turning toFIG. 20, there is shown a mask34mformed or made of a woven fabric, such as a mesh of polyester fibers. The mesh may be a cross-hatched mesh of fibers. The mask34mincludes an annular region36msurrounding an aperture38m. The annular region36mcomprises a plurality of generally regularly positioned apertures36min the woven fabric that allow some light to pass through the mask34m. The amount of light transmitted can be varied and controlled by, for example, moving the fibers closer together or farther apart, as desired. Fibers more densely distributed allow less light to pass through the annular region36m. Alternatively, the thickness of fibers can be varied to allow more or less light through the openings of the mesh. Making the fiber strands larger results in the openings being smaller.

FIG. 22shows an embodiment of a mask34nthat includes an annular region36nthat has sub-regions with different opacities. The opacity of the annular region36nmay gradually and progressively increased or decreased, as desired.FIG. 22shows one embodiment where a first area42closest to an aperture38nhas an opacity of approximately 60%. In this embodiment, a second area44, which is outlying with respect to the first area42, has a greater opacity, such as 70%. In this embodiment, a third area46, which is outlying with respect to the second area42, has an opacity of between 85 to 100%. The graduated opacity of the type described above and shown inFIG. 22is achieved in one embodiment by, for example, providing different degrees of pigmentation to the areas42,44and46of the mask34n. In another embodiment, light blocking materials of the type described above in variable degrees may be selectively deposited on the surface of a mask to achieve a graduated opacity.

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.

FIGS. 24-33show examples of masks that have been modified to provide regions of differing opacity. For example,FIG. 24shows a mask34othat includes an aperture38oand a plurality of cutouts48in the pattern of radial spokes extending from near the aperture38oto an outer periphery50of the mask34o.FIG. 24shows that the cutouts48are much more densely distributed about a circumference of the mask near aperture38othan are the cutouts48about a circumference of the mask near the outer periphery50. Accordingly, more light passes through the mask34onearer aperture38othan near the periphery50. The change in light transmission through the mask34ois gradual.

FIGS. 26-27show another embodiment of a mask34p. The mask34pincludes an aperture38pand a plurality of circular cutouts52p, and a plurality of cutouts54p. The circular cutouts52pare located proximate the aperture38p. The cutouts54pare located between the circular cutouts52pand the periphery50p. The density of the circular cutouts52pgenerally decreases from the near the aperture38ptoward the periphery50p. The periphery50pof the mask34pis scalloped by the presence of the cutouts54, which extend inward from the periphery50p, to allow some light to pass through the mask at the periphery50p.

FIGS. 28-29show another embodiment similar to that ofFIGS. 26-27wherein a mask34qincludes a plurality of circular cutouts52qand a plurality of cutouts54q. The cutouts54qare disposed along the outside periphery50qof the mask34q, but not so as to provide a scalloped periphery.

FIGS. 30 and 31illustrate an embodiment of a mask34rthat includes an annular region36rthat is patterned and an aperture38rthat is non-circular. As shown inFIG. 30, the aperture38ris in the shape of a starburst. Surrounding the aperture38ris a series of cutouts54rthat are more densely spaced toward the aperture38r. The mask34rincludes an outer periphery50rthat is scalloped to provide additional light transmission at the outer periphery50r.

FIGS. 32 and 33show another embodiment of a mask34sthat includes an annular region36sand an aperture38s. The annular region36sis located between an outer periphery50sof the mask34sand the aperture38s. The annular region36sis patterned. In particular, a plurality of circular openings56sis distributed over the annular region36sof the mask34s. It will be appreciated that the density of the openings56sis greater near the aperture38sthan near the periphery50sof the mask34s. As with the examples described above, this results in a gradual increase in the opacity of the mask34sfrom aperture38sto periphery50s.

FIGS. 34-36show further embodiments. In particular,FIG. 34shows a mask34tthat includes a first mask portion58tand a second mask portion60t. The mask portions58t,60tare generally “C-shaped.” As shown inFIG. 34, the mask portions58t,60tare implanted or inserted such that the mask portions58t,60tdefine a pinhole or aperture38t.

FIG. 35shows another embodiment wherein a mask34uincludes two mask portions58u,60u. Each mask portion58u,60uis in the shape of a half-moon and is configured to be implanted or inserted in such a way that the two halves define a central gap or opening62u, which permits light to pass therethrough. Although opening62uis not a circular pinhole, the mask portions58u,60uin combination with the eyelid (shown as dashed line64) of the patient provide a comparable pinhole effect.

FIG. 36shows another embodiment of a mask34vthat includes an aperture38vthat is in the shape of a half-moon. As discussed in more detail below, the mask34vmay be implanted or inserted into a lower portion of the cornea12where, as described above, the combination of the mask34vand the eyelid62provides the pinhole effect.

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 inFIG. 19. The gel may be a hydrogel or collagen, or other suitable material that is biocompatible with the mask material and can be introduced into the interior of the mask. The gel within the mask may include particulate66suspended within the gel. Examples of suitable particulate are gold, titanium, and carbon particulate, which, as discussed above, may alternatively be deposited on the surface of the mask.

The material of the mask34may be any biocompatible polymeric material. Where a gel is used, the material is suitable for holding a gel. Examples of suitable materials for the mask34include 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 mask34may also be made to include a medicinal fluid, such as an antibiotic that can be selectively released after application, insertion, or implantation of the mask34into the eye of the patient. Release of an antibiotic after application, insertion, or implantation provides faster healing of the incision. The mask34may 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 mask34may be provided with a releasable cholesterol deterring drug. The drug may be coated on the surface of the mask34or, in an alternative embodiment, incorporated into the polymeric material (such as PMMA) from which the mask34is formed.

FIGS. 37 and 38illustrate one embodiment where a mask34wcomprises a plurality of nanites68. “Nanites” are small particulate structures that have been adapted to selectively transmit or block light entering the eye of the patient. The particles may be of a very small size typical of the particles used in nanotechnology applications. The nanites68are suspended in the gel or otherwise inserted into the interior of the mask34w, as generally shown inFIGS. 37 and 38. The nanites68can be preprogrammed to respond to different light environments.

Thus, as shown inFIG. 37, in a high light environment, the nanites68turn and position themselves to substantially and selectively block some of the light from entering the eye. However, in a low light environment where it is desirable for more light to enter the eye, nanites may respond by turning or be otherwise positioned to allow more light to enter the eye, as shown inFIG. 38.

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 bright light environments, they rotate in the manner described above and generally shown inFIG. 38.

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.

Masks34made in accordance with the present invention may be further modified to include other properties.FIG. 39shows one embodiment of a mask34xthat includes a bar code70or other printed indicia.

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 withFIG. 52, the mask34may be provided as a contact lens placed on the surface of the eyeball10. Alternatively, the mask34may be incorporated in an artificial intraocular lens designed to replace the original lens14of the patient. Preferably, however, the mask34is provided as a corneal implant or inlay, where it is physically inserted between the layers of the cornea12.

When used as a corneal implant, layers of the cornea12are peeled away to allow insertion of the mask34. Typically, the optical surgeon (using a laser) cuts away and peels away a flap of the overlying corneal epithelium. The mask34is 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 mask34is attached or fixed to the eye10by support strands72and74shown inFIG. 40and generally described in U.S. Pat. No. 4,976,732, incorporated by reference herein in its entirety.

In certain circumstances, to accommodate the mask34, 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 cornea12to provide a pocket that will accommodate the mask34. Application of the mask34to the cornea12of the eye10of a patient is described in greater detail in connection withFIGS. 53A-54C.

Removal of the mask34may be achieved by simply making an additional incision in the cornea12, lifting the flap and removing the mask34. Alternatively, ablation techniques may be used to completely remove the mask34.

FIGS. 41 and 42illustrate another embodiment of a mask34ythat includes a coiled strand80of a fibrous or other material. Strand80is coiled over itself to form the mask34y, which may therefore be described as a spiral-like mask. This arrangement provides a pinhole or aperture38ysubstantially in the center of the mask34y. The mask34ycan be removed by a technician or surgeon who grasps the strand80with tweezers82through an opening made in a flap of the cornea12.FIG. 42shows this removal technique.

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 that of patients 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 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 benefit to the patient.

A. Alignment of the Pinhole Aperture with the Patient's Visual Axis

Alignment of the central region of the pinhole aperture38, in particular, the optical axis39, of the mask34with the visual axis of the eye10may 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.

FIG. 43is a cross-sectional view of the eye10, similar to that shown inFIG. 1, indicating a first axis1000and a second axis1004. The first axis1000represents the visual axis, or line of sight, of the patient and the second axis1004indicates the axis of symmetry of the eye10. The visual axis1000is an axis that connects the fovea20and a target1008. The visual axis1000also extends through the central point28of the entrance pupil26. The target1008is sometimes referred to herein as a “fixation point.” The visual axis1000also corresponds to the chief ray of the bundle of rays emanating from the target1008that passes through the pupil22and reaches the fovea20. The axis of symmetry1004is an axis passing through the central point28of the entrance pupil26and the center of rotation30of the eye10. As described above, the cornea12is located at the front of the eye10and, along with the iris22, admits light into the eye10. Light entering the eye10is focused by the combined imaging properties of the cornea12and the intraocular lens14(seeFIGS. 2-3).

In a normal eye, the image of the target1008is formed at the retina16. The fovea20(the region of the retina16with particularly high resolution) is slightly off-set from the axis of symmetry1004of the eye10. This visual axis1000is typically inclined at an angle θ of about six (6) degrees to the axis of symmetry1004of the eye10for an eye with a centered iris.

The reference target1016inFIG. 44Ais shown reimaged at an infinite distance, which is achieved by positioning the target object at a distance1024equal to the focal length f of the lens1012, i.e. the reference target1016is at the lens focal point. To a first-order approximation, the relationship between the object and the image distances for a lens of focal length f follows the Gaussian equation (1/A)=(1/f)+(1/B) where B and A are respectively the object and image distances measured from the lens center. Because the illuminated target appears at an infinite distance as viewed by the eye10, individual light rays1020ato1020gare parallel to each other.

FIG. 44Ashows the eye10fixated on the reference target1016along a ray1020c, which appears to come from the reference target1016as imaged by the projection lens1012. The eye10is here decentered a distance1028from an optical axis1032of the instrument, i.e., the instrument axis, which may be the central axis of the lens1012. This decentration of the eye10with respect to the optical axis1032of the instrument does not affect fixation to an infinitely distant image because all rays projected by the lens1012are parallel. As such, in an instrument that relies on fixation to a single target imaged at infinity, an eye can be fixated on the target but still be off-center of the optical axis of the instrument.

FIG. 44Bis similar toFIG. 44A, except that a reference target1016′ is located somewhat closer to the projection lens1012than is the reference target1016so that an image1036of the reference target1016′ appears at a large but finite distance1040behind the lens1012. As was the case inFIG. 44A, the eye10inFIG. 44Bis fixated on the reference target1016′ along a ray1020c′, which is decentered a distance1028from an optical axis1032of the instrument. However, the rays1020a′ to1020g′ projected by the lens1012shown inFIG. 44Bare seen to diverge as if they originated at the image1036of the reference target1016′, which is located on the optical axis1032of the lens1012at a finite distance1040from the lens1012. If the decentration of the eye10(corresponding to the distance1028) changes, the eye10must rotate somewhat about its center of rotation30in order to fixate on the image1036. The eye10inFIG. 44Bis shown rotated by some angle so as to align its visual axis1000with the direction of propagation of ray1020c′. Thus, in general, a decentered eye fixated on a finite-distance target is not merely off-center but is also angularly offset from the optical axis1032of the instrument.

FIG. 45Ashows one embodiment of a projection lens1012used to create an optical image at infinite distance, as was schematically shown inFIG. 44A. The reference target1016typically is a back-illuminated pattern on a transparent glass reticle1044. The reference target1016is located at a distance1024on the lens' optical axis1032at the lens' focal point, i.e. the reference target1016is located such that the distance1024is equal to the distance f. A diffusing plate1048and a condensing lens1052are used to ensure full illumination of the reference target1016throughout the aperture of the projection lens1012. Light rays projected by the projection lens1012are substantially parallel depending upon the degree of imaging perfection achieved in the optical system. Assuming a well-corrected lens with small aberrations, the image as observed through the aperture of the projection lens1012will appear to be at infinity.

FIG. 45Bshows a somewhat different optical system in which a target1016′ is projected so that an image1036appears at a large but finite distance1040behind the lens1012, as was shown schematically inFIG. 44B. The diffusing plate1048and the condensing lens1052again are used to ensure that full illumination of the target reference112′ is achieved throughout the aperture of the projection lens1012. In the system ofFIG. 45B, the reference target1016′ is located at an object distance1024′, which is inside the focal point in accordance with the aforementioned Gaussian equation. Thus, the object distance1024′ is a distance that is less than the focal length f of the lens1012′. The path of a typical light ray1056from the center of the reference target1016′ is shown. If the eye10is aligned with this ray1056, the reference target1016is observed as if it were located at the location of the image1036, i.e. at a finite distance. The ray1056would then be similar to ray1020c′ ofFIG. 44B, and fixation of the eye10could be established as appropriate for the given degree of decentration from the optical axis1032.

FIG. 46illustrates a fixation method whereby the single-target fixation methods shown inFIGS. 44A and 44Bare both used simultaneously in a dual-target fixation system. With two fixation targets1016and1016′ at different distances, the eye10will see angular disparity (parallax) between the target images (i.e., they will not appear to be superimposed) if the eye is decentered. The rays1020ato1020gof the infinite-distance target1016are parallel to one another, while the rays1020a′ to1020g′ of the finite distance target1016′ diverge. The only rays of the targets that coincide are rays1020dand10204d′, which are collinear along the optical axis1032of the instrument. Thus, the eye10can be simultaneously fixated on both targets if the visual axis, represented by the first axis1000of the eye10, is centered on the optical axis of the instrument, i.e. along the ray1020d(which is the same as1020d′). Thus, when the visual axis of the eye10lies on the optical axis1032of the apparatus, both images are fixated.

FIG. 47shows schematically an apparatus with which two reticle patterns could be projected simultaneously by the same projection lens to provide fixation targets1016and1016′ at a large distance1024(such as infinity) and a shorter (finite) distance1024′. It is preferable that both fixation targets are at relatively large distances so that only slight focus accommodation of the eye10is required to compensate for these different distances. By instructing the patient to move his or her eye transversely with respect to the instrument axis until a visual event occurs, e.g., angular displacement (parallax) between the images is minimized, alignment of the eye10with the optical axis1032of the apparatus is facilitated. Providing two fixation targets at different apparent distances will simplify accurate alignment of the sighted eye with an ophthalmic apparatus in the surgical procedures disclosed herein and in other similar surgical procedures.

FIG. 48shows another embodiment of an apparatus for combining two fixation targets1016and1016′ to project them simultaneously at different axial distances. A beamsplitter plate or cube1060is inserted between the patterns and the projection lens1012so each pattern can be illuminated independently. In the embodiments ofFIGS. 46 and 47, the targets1016,1016′ can be opaque lines seen against a light background, bright lines seen against a dark background, or a combination of these forms.

FIG. 49Ashows an example of a typical dual pattern as viewed by the patient when the patterns are aligned, i.e. when the patient's eye is aligned with the optical axis of the apparatus. The dual pattern set in this embodiment comprises an opaque fine-line cross1064seen against a broader bright cross1068.FIG. 49Bshows the same dual pattern set as shown inFIG. 49A, except the patterns are offset, indicating that the eye10is decentered with respect to the optical axis of the associated optical instrument.

FIG. 50Ashows an example of another dual pattern as viewed by the patient when the patterns are aligned, i.e. when the patient's eye is aligned with the optical axis of the ophthalmic instrument. The dual pattern set in this embodiment comprises an opaque circle1072seen against a bright circle1076. The circle1072has a diameter that is greater than the diameter of the circle1076.FIG. 50Bshows the same dual pattern set as shown inFIG. 50A, except the patterns are offset, indicating that the eye10is decentered with respect the optical axis of the associated optical instrument. It is not necessary that the targets appear as crosses or circles; patterns such as dots, squares, and other shapes and patterns also can suffice.

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.

FIG. 51shows one embodiment of an ophthalmic instrument1200that can be used in connection with various methods described herein to locate the visual axis of a patient. The instrument1200includes an optics housing1202and a patient locating fixture1204that is coupled with the optics housing1202. The optics housing1202includes an optical system1206that is configured to project two reticle patterns simultaneously to provide fixation targets at a large distance, e.g., infinity, and a shorter, finite distance.

In the illustrated embodiment, the optical system1206of the instrument includes a first reference target1208, a second reference target1210, and a projection lens1212. The first and second reference targets1208,1210are imaged by the projection lens1212along an instrument axis1213of the ophthalmic instrument1200. In one embodiment, the first reference target1208is formed on a first glass reticle1214located a first distance1216from the lens1212and the second target1210is formed on a second glass reticle1218located a second distance1220from the lens1212. Preferably, the second distance1220is equal to the focal length f of the lens1212, as was discussed in connection withFIG. 44A. As discussed above, positioning the second target1210at the focal length f of the lens1212causes the second target1210to be imaged at an infinite distance from the lens1212. The first distance1216preferably is less than the second distance1220. As discussed above, the first reference target1208is thereby imaged at a large but finite distance from the lens1212. By positioning the first and second reference targets1208,1210in this manner, the method set forth above for aligning the eye10of the patient may be implemented with the ophthalmic instrument1200.

The optical system1206preferably also includes a light source1222that 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 source1222is positioned separately from the first and second reference targets1208,1210. In one embodiment, the light source1222is positioned at a ninety degree angle to the instrument axis1213and is configured to direct light toward the axis1213. In the illustrated embodiment, a beamsplitter plate or cube1224is provided between the first and second reference targets1208,1210and the patient to route light rays emitted by the light source1222to the eye of the patient. The beamsplitter1224is an optical component that reflects light rays from the direction of the light source1222, but permits the light rays to pass through the beamsplitter along the instrument axis1213. Thus, light rays form the first and second reference targets1208,1210and from the light source1222may be propagated toward the eye of the patient. Other embodiments are also possible. For example, the beamsplitter1224could be replaced with a mirror that is movable into and out of the instrument axis1213to alternately reflect light from the light source1222to the eye or to permit light from the first and second reference targets1208,1210to reach the eye.

The patient locating fixture1204includes an elongate spacer1232and a contoured locating pad1234. The contoured locating pad1234defines an aperture through which the patient may look along the instrument axis213. The spacer1232is coupled with the optics housing1202and extends a distance1236between the housing1202and the contoured locating pad1234. In one embodiment, the spacer1232defines a lumen1238that extends between the contoured locating pads1234and the optics housing1202. In some embodiments, the magnitude of the distance1236may be selected to increase the certainty of the location of the patient's visual axis. In some embodiments, it is sufficient that the distance1236be a relatively fixed distance.

When the alignment apparatus1200is used, the patient's head is brought into contact with the contoured locating pad1234, which locates the patient's eye10in the aperture at a fixed distance from the first and second reference targets1208,1210. Once the patient's head is positioned in the contoured locating pad1234, the patient may move the eye10as discussed above, to locate the visual axis. After locating the visual axis, the light source1222is engaged to emit light toward the eye10, e.g., as reflected by the beamsplitter1224.

In the illustrated embodiment, at least some of the light emitted by the light source1222is reflected by the beamsplitter1224along the instrument axis1213toward the patient's eye10. Because the visual axis of the eye10was previously aligned with the instrument axis1213, the light from the light source1222reflected by the beamsplitter1224is also aligned with the visual axis of the eye10.

The reflected light provides a visual marker of the location of the patient's visual axis. The marking function of the light source1222is 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 withFIGS. 55-59.

B. Methods of Applying a Mask

Having described a method for properly locating the visual axis of the eye10of a patient and for visually marking the visual axis, various methods for applying a mask to the eye will be discussed.

FIG. 52shows an exemplary process for screening a patient interested in increasing his or her depth of focus. The process begins at step1300, in which the patient is fitted with soft contact lenses, i.e., a soft contact lens is placed in each of the patient's eyes. If needed, the soft contact lenses may include vision correction. Next, at step1310, the visual axis of each of the patient's eyes is located as described above. At a step1320, a mask, such as any of those described above, is placed on the soft contact lenses such that the optical axis of the aperture of the mask is aligned with the visual axis of the eye. In this position, the mask will be located generally concentric with the patient's pupil. In addition, the curvature of the mask should parallel the curvature of the patient's cornea. The process continues at a step1330, in which the patient is fitted with a second set of soft contact lenses, i.e., a second soft contact lens is placed over the mask in each of the patient's eyes. The second contact lens holds the mask in a substantially constant position. Last, at step1340, the patient's vision is tested. During testing, it is advisable to check the positioning of the mask to ensure that the optical axis of the aperture of the mask is substantially collinear with the visual axis of the eye. Further details of testing are set forth in U.S. Pat. No. 6,554,424, issued Apr. 29, 2003, incorporated by reference herein in its entirety.

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.

FIGS. 53athrough53cshow a mask1400inserted underneath an epithelium sheet1410. In this embodiment, the surgeon first removes the epithelium sheet1410. For example, as shown inFIG. 53a, the epithelium sheet1410may be rolled back. Then, as shown inFIG. 53b, the surgeon creates a depression1415in a Bowman's membrane420corresponding to the visual axis of the eye. The visual axis of the eye may be located as described above and may be marked by use of the alignment apparatus1200or other similar apparatus. The depression1415should be of sufficient depth and width to both expose the top layer1430of the stroma1440and to accommodate the mask1400. The mask1400is then placed in the depression1415. Because the depression1415is located in a position to correspond to the visual axis of the patient's eye, the central axis of the pinhole aperture of the mask1400will be substantially collinear with the visual axis of the eye. This will provide the greatest improvement in vision possible with the mask1400. Last, the epithelium sheet1410is placed over the mask1400. Over time, as shown inFIG. 53c, the epithelium sheet1410will grow and adhere to the top layer1430of the stroma1440, as well as the mask1400depending, of course, on the composition of the mask1400. As needed, a contact lens may be placed over the incised cornea to protect the mask.

FIGS. 54athrough54cshow a mask1500inserted beneath a Bowman's membrane1520of an eye. In this embodiment, as shown inFIG. 54a, the surgeon first hinges open the Bowman's membrane1520. Then, as shown inFIG. 54b, the surgeon creates a depression1515in a top layer1530of a stroma1540corresponding to the visual axis of the eye. The visual axis of the eye may be located as described above and may be marked by using the alignment apparatus1200or other similar apparatus. The depression1515should be of sufficient depth and width to accommodate the mask1500. Then, the mask1500is placed in the depression1515. Because the depression1515is located in a position to correspond to the visual axis of the patient's eye, the central axis of the pinhole aperture of the mask1500will be substantially collinear with the visual axis of the eye. This will provide the greatest improvement in vision possible with the mask1500. Last, the Bowman's membrane1520is placed over the mask1500. Over time, as shown inFIG. 54c, the epithelium sheet1510will grow over the incised area of the Bowman's membrane1520. As needed, a contact lens may be placed over the incised cornea to protect the mask.

In another embodiment, a mask of sufficient thinness, i.e., less than substantially 20 microns, may be placed underneath epithelium sheet1410. In another embodiment, an optic mark having a thickness less than about 20 microns may be placed beneath Bowman's membrane1520without 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

FIG. 55shows a surgical system2000that employs dual target fixation in a manner similar to that discussed above in connection withFIGS. 43-51. The surgical system2000enables the identification of a unique feature of a patient's eye in connection with a surgical procedure. The surgical system2000is similar to the ophthalmic instrument1200except as set forth below. As discussed below, in one arrangement, the surgical system2000is configured to align an axis of the patient's eye, e.g., the patient's line of sight (sometimes referred to herein as the “visual axis”), with an axis of the system2000. The axis of the system2000may be a viewing axis along which the patient may direct an eye. As discussed above, such alignment is particularly useful in many surgical procedures, including those that benefit from precise knowledge of the location of one or more structures or features of the eye on which the procedures is being performed.

In one embodiment, the surgical system2000includes a surgical viewing device2004and an alignment device2008. In one embodiment, the surgical viewing device2004includes a surgical microscope. The surgical viewing device2004may 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 device2004without a viewing device. As discussed more fully below in connection another embodiment of a surgical system shown inFIG. 56, the surgical system2000preferably also includes a fixture configured to conveniently mount one or more components to the surgical viewing device2004.

In one embodiment, the alignment device2008includes an alignment module2020, a marking module2024, and an image capture module2028. As discussed below, in another embodiment, the marking module2024is eliminated. Where the marking module2024is eliminated, one or more of its functions may be performed by the image capture module2028. In another embodiment, the image capture module2028is eliminated. The alignment device2004preferably also has a control device2032that directs one or more components of the alignment device2004. As discussed more fully below, the control device2032includes a computer2036and signal lines2040a,2040b, and a trigger2042in one embodiment.

The alignment module2020includes 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 device2008. In one embodiment, the alignment module2020includes a plurality of targets (e.g., two targets) that are located on the instrument axis. In the illustrated embodiment, the alignment module2020includes a first target2056and a second target2060. The alignment module2020may be employed to align the patient's line-of-sight with an axis2052that extends perpendicular to the faces of the targets2056,2060.

Although the alignment device2008could be configured such that the patient is positioned relative thereto so that the eye is positioned along the axis2052, it may be more convenient to position the patient such that an eye2064of the patient is not on the axis2052. For example, as shown inFIG. 55, the patient may be positioned a distance2068from the axis2052.FIG. 55shows that the gaze of the patient's eye2064is directed generally along a patient viewing axis2072.

In this arrangement, the alignment device2008is configured such that the patient viewing axis2072is at about a ninety degree angle with respect to the instrument axis2052. In this embodiment, a path2076optically connecting the targets2056,2060with the patient's eye2064extends partially along the axis2052and partially along the patient viewing axis2072. The optical path2076defines the path along which the images of the targets2056,2060are cast when the alignment device2008is configured such that the patient's eye2064is not on the axis2052.

Positioning the patient off of the axis2052, may be facilitated by one or more components that redirect light traveling along or parallel to the axis2052. In one embodiment, the alignment device2008includes a beamsplitter2080located on the axis2052to direct along the patient viewing axis2072light rays coming toward the beamsplitter2080from the direction of the targets2056,2060. In this embodiment, at least a portion of the optical path2076is defined from the patient's eye2064to the beamsplitter2080and from the beamsplitter2080to the first and second targets2056,2060. Although the alignment device2008is configured to enable the patient viewing axis2072to be at about a ninety degree angle with respect to the axis2052, other angles are possible and may be employed as desired. The arrangement ofFIG. 55is convenient because it enables a surgeon to be directly above and relatively close to the patient if the patient is positioned on his or her back on an operating table.

In one embodiment, the first target2056is on the axis2052and on the optical path2076between the second target2060and the patient's eye2064. More particularly, light rays that are directed from the second target2060intersect the first target2056and are thereafter directed toward the beamsplitter2080. As discussed more fully below, the first and second targets2056,2060are configured to project a suitable pattern toward the patient's eye2064. The patient interacts with the projected images of the first and second targets2056,2060to align the line-of-sight (or other unique anatomical feature) of the patient's eye2064or of the patient's sense of vision with an axis of the instrument, such as the axis2052, the viewing axis2072, or the optical path2076.

The first and second targets2056,2060may take any suitable form. The targets2056,2060may be similar to those hereinbefore described. The targets2056,2060may be formed on separate reticles or as part of a single alignment target. In one embodiment, at least one of the first and second targets2056,2060includes a glass reticle with a pattern formed thereon. The pattern on the first target2056and the pattern on the second target2060may be linear patterns that are combined to form a third linear pattern when the patient's line-of-sight is aligned with the axis2052or optical path2076.

Although shown as separate elements, the first and second targets2056,2060may be formed on a alignment target.FIGS. 55A-55Cshows one embodiment of an alignment target2081. The alignment target2081can be formed of glass or another substantially transparent medium. The alignment target2081includes a first surface2082and a second surface2083. The first and second surfaces2082,2083are separated by a distance2084. The distance2084is selected to provide sufficient separation between the first and second surfaces2082,2083to facilitate alignment by the patient by any of the methods described herein. In one embodiment, the alignment target2081includes a first pattern2085that may comprise a linear pattern formed on the first surface2082and a second pattern2086that may comprise a linear pattern formed on the second surface2083. The first and second patterns2085,2086are selected so that when the patient's line-of-sight is properly aligned with an axis of the alignment device2008, the first and second patterns2085,2086form a selected pattern (as inFIG. 55B) but when the patient's line-of-sight is properly aligned with an axis of the alignment device2008, the first and second patterns2085,2086do not form the selected pattern (as inFIG. 55C). In the illustrated embodiment, the first and second pattern2085,2086each are generally L-shaped. When aligned, the first and second patterns2085,2086form a cross. When not aligned, a gap is formed between the patterns and they appear as an L and an inverted L. This arrangement advantageously exploits vernier acuity, which is the ability of the eye to keenly detect misalignment of displaced lines. Any other combination of non-linear or linear patterns (e.g., other linear patterns that exploit vernier acuity) can be used as targets, as discussed above.

The first and second targets2056,2060(or the first and second patterns2085,2086) may be made visible to the patient's eye2064in any suitable manner. For example, a target illuminator2090may be provided to make the targets2056,2060visible to the eye2064. In one embodiment, the target illuminator2090is 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 targets2056,2060.

As discussed more fully below, the alignment module2020also may include one or more optic elements, such as lenses, that relatively sharply focus the images projected from the first and second targets2056,2060to present sharp images to the patient's eye2064. 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 targets2056,2060, between the first and second targets2056,2060in front of the first target2056, or behind the second target2060. 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 target2056,2060.

FIG. 55shows a series of arrows that indicate the projection of the images of the first and second targets2056,2060to the patient's eye2064. In particular, an arrow2094indicates the direction of light cast by the target illuminator2090along the axis2052toward the first and second targets2056,2060. The light strikes the first and second targets2056,2060and is absorbed by or passed through the targets to cast an image of the targets2056,2060along the axis2052in a direction indicated by an arrow2098. In the embodiment ofFIG. 55, the image of the first and second targets2056,2060intersects a beam splitter2102that forms a part of the marking module2024and the image capture module2028. The beamsplitter2102is configured to transmit the majority of the light conveying the images of the first and second targets2056,2060toward the beamsplitter2080as indicated by an arrow2106. The beamsplitter2102will be discussed in greater detail below. The light is thereafter reflected by the beamsplitter2080along the patient viewing axis2072and toward the patient's eye2064. As discussed more fully below, in some embodiments, the beamsplitter2080transmits some of the incident light beyond the beamsplitter2080along the axis2050. In one embodiment, 70 percent of the light incident on the beamsplitter2080is reflected toward the patient's eye2064and 30 percent is transmitter. One skilled in the art will recognize that the beamsplitter2080can be configured to transmit and reflect in any suitable fraction.

While the target illuminator2090and the first and second targets2056,2060project the images of the targets to the patient's eye2064, the patient may interact with those images to align a feature of the patient's eye2064with an axis of the alignment device2008. In the embodiment illustrated byFIG. 55, the patient aligns the line-of-sight of the eye2064with the patient viewing axis2072of the alignment device2008.

Techniques for aligning the line of sight of the patient's eye2064with the instrument axis have been discussed above. In the context of the embodiment ofFIG. 55, the patient is positioned such that the optical path2076intersects the patient's eye2064. In one method, the patient is instructed to focus on the first target2056. Motion is provided between the patient's eye2064and the optical path2076(and therefore between the patient's eye2064and the targets2056,2060). The relative motion between the patient's eye2064and the targets2056,2060may be provided by the patient moving his or her head with respect to the patient viewing axis2072. Alternatively, the patient may be enabled to move all or a portion of the surgical system2000while the patient remains stationary. As discussed above, when the first and second targets2056,2060appear aligned (e.g., the L patterns2085,2086merge to form a cross), the line-of-sight of the patient is aligned with the patient viewing axis2072, the optical path2076, and the axis2052of the alignment module2020.

Although aligning the eye may be sufficient to provide relatively precise placement of the masks described herein, one or both of the marking module2024and the image capture module2028may be included to assist the surgeon in placing a mask after the eye2064has been aligned. At least one of the marking module2024and the image capture module2028may be used to correlate the line-of-sight of the patient's eye2064, 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 eye2064at a pre-selected location.

In one embodiment, the marking module2024is 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 eye2064has been located. The marking module2024of the alignment device2008shown includes a marking target2120and a marking target illuminator2124. The marking target illuminator2124preferably is a source of light, such as any of those discussed above in connection with the target illuminator2090.

FIG. 55shows that in one embodiment, the marking target2120is a structure configured to produce a marking image when light is projected onto the marking target2120. The marking target2120may be similar to the targets2056,2060. In some embodiments, the marking target2120is a glass reticle with a suitable geometrical pattern formed thereon. The pattern formed on the marking target2120may be a clear two dimensional shape that is surrounded by one or more opaque regions. For example, a clear annulus of selected width surrounded by opaque regions could be provided. In another embodiment, the marking target2120may be a glass reticle with an opaque two dimensional shape surrounded by substantially clear regions. As discussed below, in other embodiments, the marking target2120need not be made of glass and need not have a fixed pattern. The marking target2120may be located in any suitable location with respect to the beamsplitter2080or the alignment device2008as discussed below.

FIG. 55shows that in one embodiment, the marking image is generated in a manner similar to the manner in which the images of the first and second targets2056,2060are generated. In particular, the marking target2124and the marking target illuminator2124cooperate to produce, generate, or project the marking image along a marking image axis2128. The marking image is conveyed by light along the axis2128. The marking target illuminator2124casts light toward the marking target2120in a direction indicated by an arrow2132. The marking target2120interacts with the light cast by the marking target illuminator2124, e.g., by at least one of transmitting, absorbing, filtering, and attenuating at least a portion of the light. An arrow2136indicates the direction along which the marking image generated by the interaction of the marking target illuminator2124and the marking target2120is conveyed. The marking image preferably is conveyed along the marking axis2128. In the illustrated embodiment, the marking target2120is located off of the axis2052and the image of the marking target initially is cast in a direction generally perpendicular to the axis2052.

A beamsplitter2140, to be discussed below in connection with the image capture module2028, is positioned on the marking axis2128in the embodiment ofFIG. 55. However, the beamsplitter2140is configured to be substantially transparent to light being transmitted along the marking axis2128from the direction of the marking target2120. Thus, the light conveying the marking image is substantially entirely transmitted beyond the beamsplitter2140along the marking axis2128toward the axis2052as indicated by an arrow2144. Thus, the beamsplitter2140generally does not affect the marking image. A surface of the beamsplitter2102that faces the marking target2120is reflective to light. Thus, the light conveying the marking image is reflected and thereafter is conveyed along the axis2052as indicated by the arrow2106. The surface of the beamsplitter2080that faces the beamsplitter2102also is reflective to at least some light (e.g., 70 percent of the incident light, as discussed above). Thus, the light conveying the marking image is reflected and thereafter is conveyed along the patient viewing axis2072toward the patient's eye2064as indicated by the arrow2148. Thus, a marking image projected from the marking target2120may be projected onto the patient's eye2064.

As discussed more fully below, projecting the marking image onto the patient's eye2064may 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 eye2064) 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 eye2064). 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 eye2064). In another technique, the marking image is a substantially circular ring that has a size that is correlated to another feature of the eye2064, e.g., the limbus of the eye.

In one embodiment of the system2000, 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 device2008. Rather, the secondary marking module is coupled with the alignment device2008. 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 eye2064. The spots preferably are small, bright spots. The spots indicate positions on the eye2064that 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 eye2064. 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 module2024in 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 target2120) on the eye2064. 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 target2120. For example, a dye, such as fluorescein dye, can be applied to the surface of the eye. Then the marking target illuminator2124may be activated to cause an image of the marking target2120to be projected onto the eye, as discussed above. In one embodiment, the marking target illuminator2124is 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 target2120onto the eye2064. The projected image interacts with the dye and causes the image of the marking target2120to 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 target2120is 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 target2120.

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 eye2064. 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 target2120onto 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 device2008shown inFIG. 55also includes an image capture module2028. Some variations do not include the image capture module2028. The image capture module2028of the surgical system2000is capable of capturing one or more images of the patient's eye2064to assist the surgeon in performing surgical procedures on the eye2064. The image capture module2028preferably includes a device to capture an image, such as a camera2200and a display device2204to display an image. The display device2204may be a liquid crystal display. The image capture module2028may be controlled in part by the control device2032of the surgical system2000. For example, the computer2036may be employed to process images captured by the camera2200and to convey an image to the display device2204where it is made visible to the surgeon. The computer2036may also direct the operation of or be responsive to at least one of the camera2200, the display device2204, the trigger2042, and any other component of the image capture module2028.

The camera2200can 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 device2204) with the axis2052. When such alignment is provided, the marking module may not be needed to align a mask with the line-of-sight of the eye2064.

As discussed above, an image captured by the camera2200aids the surgeon attempting to align a mask, such as any of the masks described herein, with the eye2064. In one arrangement, the image capture module2028is configured to capture an image of one or more physical attributes of the eye2064, the location of which may be adequately correlated to the line-of-sight of the eye2064. For example, the image of the patient's iris may be directed along the patient viewing axis2072to the beamsplitter2080as indicated by the arrow2148. As mentioned above, a side of the beamsplitter2080that faces the beamsplitter2080is reflective to light transmitted from the eye2064. Thus, at least a substantial portion of the light conveying the image of the iris of the eye2064is reflected by the beamsplitter2080and is conveyed along the axis2052toward the beamsplitter2102, as indicated by the arrow2106. As discussed above, the surface of the beamsplitter2102facing the beamsplitter2080is reflective to light. Thus, substantially all of the light conveying the image of the iris is reflected by the beamsplitter2102and is conveyed along the marking axis2128toward the beamsplitter2140, as indicated by the arrow2144. The surface of the beamsplitter2140facing the beamsplitter2102and the camera2200is reflective to light. Thus, substantially all of the light conveying the image of the iris is reflected along an image capture axis2212that extends between the beamsplitter2140and the camera2200. The light is conveyed along an image capture axis2212as indicated by an arrow2216.

The image captured by the camera2200is conveyed to the computer2036by way of a signal line2040a. The computer2036processes the signal in a suitable manner and generates signals to be conveyed along a signal line2040bto the display device2204. Any suitable signal line and computer or other signal processing device can be used to convey signals from the camera2200to the display device2204. The signal lines2040a,2040bneed 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 camera2200may be triggered in any suitable way. For example, the trigger2042may be configured to be manually actuated. In one embodiment, the trigger2042is configured to be actuated by the patient when his or her eye2064is aligned (e.g., when the targets2056,2060are aligned, as discussed above). By enabling the patient to trigger the capturing of the image of the eye2064by the image capture module2028, the likelihood of the eye2064moving 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 device2032may be configured to automatically capture the image of the patient's eye2064based on a predetermined criteria.

The display device2204is configured to be illuminated to direct an image along the axis2052toward the beamsplitter2080as indicated by an arrow2208. The surface of the beamsplitter2080that faces the display device2204preferably is reflective to light directed from the location of the beamsplitter2080. Thus, the image on the display2052is reflected by the beamsplitter2080toward an eye2212of the surgeon as indicated by an arrow2216. The beamsplitter2080preferably is transparent from the perspective of the surgeon's eye2212. Thus, the surgeon may simultaneously view the patient's eye2064and the image on the display device2204in one embodiment. In one embodiment where both the marking module2024and the image capture module2028are present, the marking image may be projected at the same time that an image is displayed on the display device2204. 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 device2204is located at a distance2220from the beamsplitter2080. The patient is located a distance2224from the axis2052. Preferably the distance2220is about equal to the distance2224. Thus, both the display device2204and the patient's eye2064are at the focal length of the surgical viewing device2004. This assures that the image generated by the display device2204is in focus at the same time that the patient's eye is in focus.

In one embodiment, the system2000is configured to track movement of the patient's eye2064during the procedure. In one configuration, the trigger2042is actuated by the patient when the eye2064is aligned with an axis of the alignment device2008. 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 module2028may be configured to respond to such movements by moving the image formed on the display device2204. For example, a ring may be formed on the display device2204that is similar to those discussed above in connection with the marking target2120. The beamsplitter2080enables the surgeon to see the ring visually overlaid on the patient's eye2064. The image capture module2028compares the real-time position of the patient's eye2064with the image of the eye captured when the trigger2042is actuated. Differences in the real-time position and the position captured by the camera2200are 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 system2000are contemplated. A first variation is substantially identical to the embodiment shown inFIG. 55, except as set forth below. In the first variation, the video capture module2028is eliminated. This embodiment is similar to that set forth above in connection withFIG. 51. In the arrangement ofFIG. 55, the marking module2024is configured to project the marking target onto the surface of the patient's eye. This variation is advantageous in that it has a relatively simple construction. Also, this variation projects the marking image onto the surface of the cornea, proximate the surgical location.

In one implementation of the first variation, the marking module2024is configured to display the marking image to the surgeon's eye2212but not to the patient's eye2064. This may be provided by positioning the marking target2120approximately in the location of the display device2204. The marking image may be generated and presented to the surgeon in any suitable manner. For example, the marking target2120and marking target illuminator2124may be repositioned so that they project the image of the marking target2120as indicated by the arrows2208,2216. The marking target2120and the marking target illuminator2124may 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 eye2212of the surgeon. In one form, this implementation has a marking module2024similar to that shown inFIG. 55and discussed above, except as set forth below. A virtual image is presented to the surgeon's eye2212. In one form, a virtual image generation surface is positioned in substantially the same location as the display device2204. The surface may be a mirror, another reflective surface, or a non-reflective surface. In one embodiment, the display device2204is a white card. A first fraction of the light conveying the marking image is reflected by the beamsplitter2080to the patient's eye2064. The marking image is thus formed on the patient's eye. A second fraction of the light conveying the marking image is transmitted to the virtual image generation surface. The marking image is formed on or reflected by the virtual image generation surface. The marking target thus also is visible to the surgeon's eye2212in the form of a virtual image of the target. The virtual image and the marking image formed on the patient's eye are both visible to the surgeon. This implementation of the first variation is advantageous in that the virtual image and the marking image of the marking target are visible to the surgeon's eye2212and are reinforced each other making the marking image highly visible to the surgeon.

In a second variation, the marking module2024is eliminated. In this embodiment, the image capture module2028provides a visual cue for the surgeon to assist in the placement of a mask. In particular, an image can be displayed on the display device2204, as discussed above. The image can be generated in response to the patient actuating the trigger2042. In one technique, the patient actuates the trigger when the targets2056,2060appear aligned, as discussed above. In this variation, care should be taken to determine the position of the display device2204in the alignment device because the image formed on the display device2204is to give the surgeon a visual cue indicating the location of the line-of-sight of the patient. In one embodiment, the display device2204is carefully coupled with the alignment module so that the axis2052extends through a known portion (e.g., a known pixel) thereof. Because the precise location of the axis2052on the display device2204is known, the relationship of the image formed thereon to the line-of-sight of the patient is known.

FIG. 56shows a portion of a surgical system2400that is similar to the surgical system2000discussed above except as set forth below. The surgical system2400may be modified according to any of the variations and embodiments hereinbefore described.

The portion of the surgical system2400is shown from the surgeon's viewpoint inFIG. 56. The surgical system2400includes an alignment device2404and a fixture2408. The alignment device2404is similar to the alignment device2008discussed above, except as set forth below. The surgical system2400is shown without a surgical microscope or other viewing device, but is configured to be coupled with one by way of the fixture2408.

The fixture2408may take any suitable form. In the illustrated embodiment, the fixture2408includes a clamp2412, an elevation adjustment mechanism2416, and suitable members to interconnect the clamp2408and the mechanism2416. In the embodiment ofFIG. 56, the clamp2412is a ring clamp that includes a first side portion2420, a second side portion2424, and a clamping mechanism2426to actuate the first and second side portion2420,2424with respect to each other. The first side portion2420has a first arcuate inner surface2428and the second side portion2424has a second arcuate inner surface2432that faces the first arcuate inner surface2428. The clamping mechanism2426is coupled with each of the first and second side portions2420,2424to cause the first and second arcuate inner surfaces2428,2432to move toward or away from each other. As the first and second arcuate inner surfaces2428,2432move toward each other they apply a force to a structure, such as a portion of a surgical microscope, placed between the first and second arcuate inner surfaces2428,2432. In one embodiment, the force applied by the first and second arcuate inner surfaces2428,2432is sufficient to clamp the alignment device2404with respect to a surgical viewing aid. In one embodiment, the clamp2412is configured to couple with any one of (or more than one of) the currently commercially available surgical microscopes.

The fixture2408preferably also is configured to suspend the alignment device2404at an elevation below the clamp2412. In the illustrated embodiment, a bracket2440is coupled with the clamp2412, which is an L-shaped bracket in the illustrated embodiment with a portion of the L extending downward from the clamp2412.FIG. 56shows the L-shaped bracket spaced laterally from the clamp2412by a spacer2444. In one embodiment, the bracket2440is pivotably coupled with the spacer2444so that the alignment device2404can be easily rotated out of the field of view of the surgical microscope or viewing aid, which is visible through the spaced defined between the surfaces2428,2432.

Preferably the fixture2408is also configured to enable the alignment device2404to be positioned at a selected elevation within a range of elevations beneath the clamp2412. The elevation of the alignment device2404may be easily and quickly adjusted by manipulating a suitable mechanism. For example, manual actuation may be employed by providing a knob2460coupled with a rack-and-pinion gear coupling2464. Of course the rack-and-pinion gear coupling2464can be actuated by another manual device that is more remote, such as by a foot pedal or trigger or by an automated device.

FIGS. 57-59show further details of the alignment device2404. The alignment device2404is operatively coupled with an illuminator control device2500and includes an alignment module2504, a marking module2508, and an image routing module2512. As discussed below, the illuminator control device2500controls light or energy sources associated with the alignment control device2404. In some embodiments, the illuminator control device2500forms a part of a computer or other signal processing device, similar to the computer2036discussed above.

The alignment module2504is similar to the alignment module2020except as set forth below. The alignment module2504includes a housing2520that extends between a first end2524and a second end2528. The first end2524of the housing2520is coupled with the image routing module2512and interacts with the image routing module2512in a manner described below. The housing2520includes a rigid body2532that preferably is hollow. An axis2536extends within the hollow portion of the housing2520between the first and second ends2524,2528. In the illustrated embodiment, the second end2528of the housing2520is enclosed by an end plate2540.

The housing2520is configured to protect a variety of components that are positioned in the hollow spaced defined therein. In one embodiment, a target illuminator2560is positioned inside the housing2520near the second end2528thereof. A power cable2564(or other electrical conveyance) that extends from the end plate2540electrically connects the target illuminator2560to a power source. The target illuminator2560could also be triggered and powered by a wireless connection. In one arrangement, the power source forms a portion of the illuminator control device2500to which the power cable2564is 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 device2500enables the surgeon (or other person assisting in a procedure) to control the amount of energy supplied to the target illuminator2560in the alignment module2504. In one embodiment, the illuminator control device2500has a brightness control so that the brightness of the target illumination2560can be adjusted. The brightness control may be actuated in a suitable manner, such as by a brightness control knob2568. 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 illuminator2560or to provide manual digital (e.g., discrete) adjustment of the amount of energy applied to the target illuminator2560. In some embodiments, the brightness control may be adjustable automatically, e.g., under computer control. The illuminator control device2500may also have an on-off switch2572configured to selectively apply and cut off power to the target illuminator2560. The on-off switch2572may 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 housing2520are a first target2592, a second target2596, and a lens2600. As discussed above, the first and second targets2592,2596are 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 axis2536) of the alignment module2504. The first and second targets2592,2596are similar to the targets discussed above. In particular, the alignment target2081, which includes two targets on opposite ends of a single component, may be positioned within the housing2520.

The lens2600may be any suitable lens. Preferably the lens2600is configured to sharply focus one or both of the images of the first and second targets2592,2596in a manner similar to the focus of the targets2056,2060, discussed above.

In one embodiment, the alignment module2504is configured such that the position of the first and second targets2592,2596within the housing2520can be adjusted. The adjustability of the first and second targets2592,2596may be provided with any suitable arrangement.FIGS. 57-58shows that in one embodiment the alignment module2504includes a target adjustment device2612to provide rapid gross adjustment and fine adjustment of the positions of the targets2592,2596within the housing2520.

In one embodiment, the target adjustment device2612includes a support member2616that extends along at least a portion of the housing2520between the first end2524and the second end2528. In one embodiment, the support member2616is coupled with the end plate2540and with the image routing module2512. In one embodiment, the target adjustment device2612includes a lens fixture2620that is coupled with the lens2600and a target fixture2624that is coupled with the first and second targets2592,2596. In another embodiment, each of the first and second targets2592,2596is coupled with a separate target fixture so that the targets may be individually positioned and adjusted. The lens2600may be adjustable as shown, or in a fixed position. Movement of the lens and the targets2592,2596enable the patterns on the targets2592,2596to be brought into focus from the patient's point of view.

In one arrangement, the support member2616is a threaded rod and each of the first and second target fixtures2620,2624has a corresponding threaded through hole to receive the threaded support member2616. Preferably an adjustment device, such as a knob2628is coupled with the threaded support member2616so that the support member2616may be rotated. The knob2628may be knurled to make it easier to grasp and rotate. Rotation of the support member2616causes the first and second target fixtures2620,2624to translate on the support member2616along the outside of the housing2520. The movement of the first and second target fixtures2620,2624provides a corresponding movement of the first and second targets2592,2596within the housing2520.

In one embodiment a quick release mechanism2640is provided to enable the first and second target fixtures2620,2624selectively to clamp and to release the support member2616. The quick release mechanism2640can be a spring loaded clamp that causes the through holes formed in the first and second target fixtures2620,2624to open to create a gap through which the support member2616can pass. When the first and second target fixtures2620,2624are removed from the support member2616, the can be quickly moved to another position on the support member2616. After rapid repositioning, fine positioning of the first and second target fixtures2620,2624may be achieved with by turning the support member2616.

As discussed above, the alignment device2404also includes a marking module2508that is similar to the marking module2024described above, except as set forth below. The marking module includes a housing2642that is generally rigid and that defines a hollow space within the housing. The housing2642includes a first end2644that is coupled with the image routing module2512and a second end2648that is closed by an end plate2652. In one embodiment, the housing2642includes a first portion2656and a second portion2660. The first and second portions2656,2660preferably are configured to be disengaged from each other so that components located in the hollow space defined in the housing2642to be accessed. Such rapid access facilitates servicing and reconfiguring of the components located in the housing2642. The first portion2656extends between the first end2644and a midpoint of the housing2642. The second portion2660extends between the first portion2656and the second end2648of the housing2642. In one embodiment, the first portion2656has a male member with external threads and the second portion2660has a female member with internal thread such that the first and second portions2656,2660may be engaged with and disengaged from each other by way of the threads.

As discussed above, the housing2642provides a space in which one or more components may be positioned. In the illustrated embodiment, the housing2642encloses a marking target illuminator2680and a marking target2684.

The marking target illuminator2680may 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 illuminator2680may 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 target2684.

In the illustrated embodiment, the marking target illuminator2680is located near the end plate2652. A power cable2688(or other electrical conveyance) that extends from the end plate2652electrically connects the marking target illuminator2680to a power source. In one arrangement, the power source forms a portion of the illuminator control device2500to which the power cable2688is 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 device2500enables the surgeon (or other person assisting in a procedure) to control the amount of energy supplied to the target illuminator2680in the marking module2508. The illuminator control device2500has a brightness control so that the brightness of the marking target illumination2680can be adjusted. The brightness control may be actuated in a suitable manner, such as by a brightness control knob2692. The brightness control may be similar to that discussed above in connection with the brightness control of the target illuminator2560. The illuminator control device2500may also have an on-off switch2696configured to selectively apply and cut off power to the marking target illuminator2680. The on-off switch2696may 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 target2684is a reticle, e.g., made of glass, with an annular shape formed thereon. For example, the annular shape formed on the marking target2684may be a substantially clear annulus surrounded by opaque regions. In this configuration, light directed toward the marking target2684interacts with the marking target2684to produce and annular image. In another embodiment, the marking target2684may be a substantially clear reticle with an opaque shape, such as an opaque annular shape. The annular image is directed into the image routing device2684, as discussed further below. The marking target2684may be housed in a fixture2718that is removable, e.g., when the first portion2656and the second portion2660of the housing2642are decoupled. The first portion2656of the housing2642is configured to engage the fixture2718to relatively precisely position the marking target2684with respect to an axis of the housing2642.

FIG. 59shows the image routing module2512in greater detail. The image routing module2512is primarily useful for routing light that conveys the target and marking images to an eye of a patient. The image routing module2512provides flexibility in the positioning of the various components of the alignment device2404. For example, the image routing module2512enables the housing2520and the housing2556to be generally in the same plane and positioned generally parallel to each other. This provides a relatively compact arrangement for the alignment device2404, which is advantageous in the surgical setting because, as discussed above, it is desirable for the surgeon to be as close to the surgical site as possible. In addition, the compact arrangement of the alignment device2404minimizes or at least reduces the extent to which the alignment device2404interferes with free movement of the surgeon and others assisting the surgeon.

FIGS. 58 and 59shows that the image routing module2512includes a housing2720that is coupled with the first end2524and the housing2520and with the first end2644of the housing2642. A space defined within the housing2720houses a first optic device2728and a second optic device2732. The first optic device2728has a reflective surface that faces the marking target2684and is configured to reflect light conveying an image of the marking target2684toward the second optic device2732. The first optic device2728may be a mirror. The second optic device2732has a surface2736that faces the first optic device2728and is reflective to light from the first optic device2728. The second optic device2732thus reflects light that is directed toward it by the first optic device2728.

The image routing module2512also may include a third optic device2740and a frame2744coupled with the housing2720. The frame2744is configured to position and orient the third optic device2740with respect to the housing2720. In one embodiment, the third optic device2740is a beamsplitter and the frame2744holds the third optic device2740at about a forty-five degree angle with respect to the axis2520. In this position, the third optic device2740interacts with light reflected by the first surface2736of the second optic device2732. The third optic device2740may operate in a manner similar to the beamsplitter2080ofFIG. 55.

The second optic device2732is configured to be transparent to substantially all of the light conveying an image along the axis2536such that the image conveyed along the axis2536may be directed to the third optic device2740and thereafter to an eye of a surgeon, as discussed about in connection withFIG. 55.

Although the image routing device is shown with first, second, and third optic devices2728,2732,2740to route light conveying images in a particular manner, one skilled in the art will recognize that the image routing device2512could have more or fewer optic devices that route the image, depending on the desired geometry and compactness of the alignment device2404.

A variation of the alignment device2404provides a marking module with a secondary marking module not routed through the optics of the alignment device2404. 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 eye2064. 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 frame2744in one embodiment. A laser of the secondary marking module could be attached to the frame2744and 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.

FIGS. 60-61show one embodiment of a mask3000configured to increase depth of focus of an eye of a patient suffering from presbyopia. The mask3000is similar to the masks hereinbefore described, except as set forth below. Also, the mask3000can be formed by any suitable process, such as those discussed below in connection withFIGS. 67a-67dwith variations of such processes. The mask3000is configured to be applied to an eye of a patient, e.g., by being implanted in the cornea of the patient. The mask3000may be implanted within the cornea in any suitable manner, such as those discussed above in connection withFIGS. 53A-54C.

In one embodiment, the mask3000includes a body3004that has an anterior surface3008and a posterior surface3012. In one embodiment, the body3004is 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 layer1410) and a second corneal layer (e.g., the layer1430). The body3004may 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 body3004has relatively high water content.

In one embodiment, the mask3000includes and a nutrient transport structure3016. The nutrient transport structure3016may comprise a plurality of holes3020. The holes3020are shown on only a portion of the mask3000, but the holes3020preferably are located throughout the body3004in one embodiment. In one embodiment, the holes3020are arranged in a hex pattern, which is illustrated by a plurality of locations3020′ inFIG. 62A. As discussed below, a plurality of locations may be defined and later used in the later formation of a plurality of holes3020on the mask3000. The mask3000has an outer periphery3024that defines an outer edge of the body3004. In some embodiments, the mask3000includes an aperture3028at least partially surrounded by the outer periphery3024and a non-transmissive portion3032located between the outer periphery3024and the aperture3028.

Preferably the mask3000is symmetrical, e.g., symmetrical about a mask axis3036. In one embodiment, the outer periphery3024of the mask3000is circular. The masks in general have has a diameter within the range of from about 3 mm to about 8 mm, often within the range of from about 3.5 mm to about 6 mm, and 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 mask3000is circular and has a diameter of less than 4 mm. The outer periphery3024has 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 body3004of the mask3000may be configured to coupled with a particular anatomical region of the eye. The body3004of the mask3000may 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 mask3000is to be coupled with an ocular structure that has curvature, the body3004may be provided with an amount of curvature along the mask axis3036that corresponds to the anatomical curvature. For example, one environment in which the mask3000may 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 mask3000within the cornea, at least one of the anterior and posterior surfaces3008,3012of the mask3000may be provided with an amount of curvature corresponding to that of the layers of the cornea between which the mask3000is applied.

In some embodiments, the mask3000has a desired amount of optical power. Optical power may be provided by configuring the at least one of the anterior and posterior surfaces3008,3012with curvature. In one embodiment, the anterior and posterior surfaces3008,3012are provided with different amounts of curvature. In this embodiment, the mask3000has varying thickness from the outer periphery3024to the aperture3028.

In one embodiment, one of the anterior surface3008and the posterior surface3012of the body3004is 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 surfaces3008,3012are substantially planar. In general, the thickness of the inlay may be within the range of from about 1 micron to about 40 micron, and often in the range of from about 5 micron to about 20 micron. In one embodiment, the body3004of the mask3000has a thickness3038of between about 5 micron and about 10 micron. In one embodiment, the thickness3038of the mask3000is about 5 micron. In another embodiment, the thickness3038of the mask3000is about 8 micron. In another embodiment, the thickness3038of the mask3000is about 10 micron.

Thinner masks generally are more suitable for applications wherein the mask3000is implanted at a relatively shallow location in (e.g., close to the anterior surface of) the cornea. In thinner masks, the body3004may 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 mask3000. In one application, the mask3000is configured to be implanted about 5 um beneath the anterior surface of the cornea. In another application, the mask3000is configured to be implanted about 65 um beneath the anterior surface of the cornea. In another application, the mask3000is configured to be implanted about 125 um beneath the anterior surface of the cornea. Further details regarding implanting the mask3000in the cornea are discussed above in connection withFIGS. 53A-54C.

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 mask3000can 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 body3004.

In some embodiments, the mask3000is configured specifically for the manner and location of coupling with the eye. In particular, the mask3000may 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 thickness3038of the body3004of the mask3000may be varied based on where the mask3000is 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 aperture3028is configured to transmit substantially all incident light along the mask axis3036. The non-transmissive portion3032surrounds at least a portion of the aperture3028and substantially prevents transmission of incident light thereon. As discussed in connection with the above masks, the aperture3028may be a through-hole in the body3004or a substantially light transmissive (e.g., transparent) portion thereof. The aperture3028of the mask3000generally is defined within the outer periphery3024of the mask3000. The aperture3028may take any of suitable configurations, such as those described above in connection withFIGS. 6-42.

In one embodiment, the aperture3028is substantially circular and is substantially centered in the mask3000. The size of the aperture3028may be any size that is effective to increase the depth of focus of an eye of a patient suffering from presbyopia. For example, the aperture3028can 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 aperture3028is circular and has a diameter of about 1.8 mm or less. Most apertures will have a diameter within the range of from about 1.0 mm to about 2.5 mm, and often within the range of from about 1.3 mm to about 1.9 mm.

The non-transmissive portion3032is configured to prevent transmission of radiant energy through the mask3000. For example, in one embodiment, the non-transmissive portion3032prevents transmission of substantially all of at least a portion of the spectrum of the incident radiant energy. In one embodiment, the non-transmissive portion3032is 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 portion3032may substantially prevent transmission of radiant energy outside the range visible to humans in some embodiments.

As discussed above in connection withFIG. 3, preventing transmission of light through the non-transmissive portion3032decreases the amount of light that reaches the retina and the fovea that would not converge at the retina and fovea to form a sharp image. As discussed above in connection withFIG. 4, the size of the aperture3028is such that the light transmitted therethrough generally converges at the retina or fovea. Accordingly, a much sharper image is presented to the eye than would otherwise be the case without the mask3000.

In one embodiment, the non-transmissive portion3032prevents transmission of about 90 percent of incident light. In another embodiment, the non-transmissive portion3032prevents transmission of about 92 percent of all incident light. The non-transmissive portion3032of the mask3000may 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 body3004is configured to be opaque to more than 99 percent of the light incident thereon.

As discussed above, the non-transmissive portion3032may be configured to prevent transmission of light without absorbing the incident light. For example, the mask3000could 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 mask3000also has a nutrient transport structure that in some embodiments comprises the plurality of holes3020. The presence of the plurality of holes3020(or other transport structure) may affect the transmission of light through the non-transmissive portion3032by potentially allowing more light to pass through the mask3000. In one embodiment, the non-transmissive portion3032is configured to absorb about 99 percent or more of the incident light from passing through the mask3000without holes3020being present. The presence of the plurality of holes3020allows more light to pass through the non-transmissive portion3032such that only about 92 percent of the light incident on the non-transmissive portion3032is prevented from passing through the non-transmissive portion3032. The holes3020may reduce the benefit of the aperture3028on 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 aperture3028due to the holes3020is balanced by the nutrient transmission benefits of the holes3020. In one embodiment, the transport structure3016(e.g., the holes3020) is capable of substantially maintaining natural nutrient flow from a first corneal layer (i.e., one that is adjacent to the anterior surface3008of the mask3000) to the second corneal layer (i.e., one that is adjacent to the posterior surface3012of the mask3000). The plurality of holes3020are configured to enable nutrients to pass through the mask3000between the anterior surface3008and the posterior surface3012. As discussed above, the holes3020of the mask3000shown inFIG. 60may be located anywhere on the mask3000. Other mask embodiments described herein below locate substantially all of the nutrient transport structure in one or more regions of a mask.

The holes3020ofFIG. 60extends at least partially between the anterior surface3008and the posterior surface3012of the mask3000. In one embodiment, each of the holes3020includes a hole entrance3060and a hole exit3064. The hole entrance3060is located adjacent to the anterior surface3008of the mask3000. The hole exit3064is located adjacent to the posterior surface3012of the mask3000. In one embodiment, each of the holes3020extends the entire distance between the anterior surface3008and the posterior surface3012of the mask3000.

The transport structure3016is configured to maintain the transport of one or more nutrients across the mask3000. The transport structure3016of the mask3000provides sufficient flow of one or more nutrients across the mask3000to prevent depletion of nutrients at least at one of the first and second corneal layers (e.g., the layers1410and1430). One nutrient of particular importance to the viability of the adjacent corneal layers is glucose. The transport structure3016of the mask3000provides sufficient flow of glucose across the mask3000between the first and second corneal layers to prevent glucose depletion that would harm the adjacent corneal tissue. Thus, the mask3000is capable of substantially maintaining nutrient flow (e.g., glucose flow) between adjacent corneal layers. In one embodiment, the nutrient transport structure3016is 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 holes3020may be configured to maintain the transport of nutrients across the mask3000. In one embodiment, the holes3020are 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 holes3020have a diameter in the range of about 0.020 mm to about 0.029 mm. The number of holes in the plurality of holes3020is selected such that the sum of the surface areas of the hole entrances3060of all the holes3000comprises about 5 percent or more of surface area of the anterior surface3008of the mask3000. In another embodiment, the number of holes3020is selected such that the sum of the surface areas of the hole exits3064of all the holes3020comprises about 5 percent or more of surface area of the posterior surface3012of the mask3000. In another embodiment, the number of holes3020is selected such that the sum of the surface areas of the hole exits3064of all the holes3020comprises about 5 percent or more of surface area of the posterior surface3012of the mask3012and the sum of the surface areas of the hole entrances3060of all the holes3020comprises about 5 percent or more of surface area of the anterior surface3008of the mask3000.

Each of the holes3020may have a relatively constant cross-sectional area. In one embodiment, the cross-sectional shape of each of the holes3020is substantially circular. Each of the holes3020may comprise a cylinder extending between the anterior surface3008and the posterior surface3012.

The relative position of the holes3020is of interest in some embodiments. As discussed above, the holes3020of the mask3000are hex-packed, e.g., arranged in a hex pattern. In particular, in this embodiment, each of the holes3020is separated from the adjacent holes3020by a substantially constant distance, sometimes referred to herein as a hole pitch3072. In one embodiment, the hole pitch3072is about 0.062 mm.

In a hex pattern, the angles between lines of symmetry are approximately 60 degrees. The sparing of holes along any line of holes is generally within the range of from about 30 microns to about 100 microns, and, in one embodiment, is approximately 60 microns. The hole diameter is generally within the range of from about 10 microns to about 100 microns, and in one embodiment, is approximately 20 microns. The hole spacing and diameter are related if you want to control the amount of light coming through. The light transmission is a function of the sum of hole areas as will be understood by those of skill in the art in view of the disclosure herein.

The embodiment ofFIG. 60advantageously enables nutrients to flow from the first corneal layer to the second corneal layer. The inventors have discovered that negative visual effects can arise due to the presence of the transport structure3016. For example, in some cases, a hex packed arrangement of the holes3020can generate diffraction patterns visible to the patient. For example, patients might observe a plurality of spots, e.g., six spots, surrounding a central light with holes3020having a hex patterned.

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.

FIG. 62B-62Cshow two embodiments of patterns of holes4020that may be applied to a mask that is otherwise substantially similar to the mask3000. The holes4020of the hole patterns ofFIGS. 62A-62Bare spaced from each other by a random hole spacing or hole pitch. In other embodiments discussed below, holes are spaced from each other by a non-uniform amount, e.g., not a random amount. In one embodiment, the holes4020have a substantially uniform shape (cylindrical shafts having a substantially constant cross-sectional area).FIG. 62Cillustrates a plurality of holes4020separated by a random spacing, wherein the density of the holes is greater than that ofFIG. 62B. Generally, the higher the percentage of the mask body that has holes the more the mask will transport nutrients in a manner similar to the native tissue. One way to provide a higher percentage of hole area is to increase the density of the holes. Increase hole density can also permit smaller holes to achieve the same nutrient transport as is achieved by less dense, larger holes.

FIG. 63Ashows a portion of another mask4000athat is substantially similar to the mask3000, except as set forth below. The mask4000acan be formed by any suitable process, such as those discussed below in connection withFIGS. 67a-67dand with variations of such processes. The mask4000ahas a plurality of holes4020a. A substantial number of the holes4020ahave a non-uniform size. The holes4020amay be uniform in cross-sectional shape. The cross-sectional shape of the holes4020ais substantially circular in one embodiment. The holes4020amay be circular in shape and have the same diameter from a hole entrance to a hole exit, but are otherwise non-uniform in at least one aspect, e.g., in size. It may be preferable to vary the size of a substantial number of the holes by a random amount. In another embodiment, the holes4020aare non-uniform (e.g., random) in size and are separated by a non-uniform (e.g., a random) spacing.

FIG. 63Billustrates another embodiment of a mask4000bthat is substantially similar to the mask3000, except as set forth below. Also, the mask4000bcan be formed by any suitable process, such as those discussed below in connection withFIGS. 67a-67dand with variations of such processes. The mask4000bincludes a body4004b. The mask4000bhas a transport structure4016bthat includes a plurality of holes4020bwith a non-uniform facet orientation. In particular, each of the holes4020bhas a hole entrance4060bthat may be located at an anterior surface4008bof the mask4000b. A facet4062bof the hole entrance4060bis defined by a portion of the body4004bof the mask4000bsurrounding the hole entrance4060b. The facet4062bis the shape of the hole entrance4060bat the anterior surface4008b. In one embodiment, most or all the facets4062bhave an elongate shape, e.g., an oblong shape, with a long axis and a short axis that is perpendicular to the long axis. The facets4062bmay be substantially uniform in shape. In one embodiment, the orientation of facets4062bis not uniform. For example, a substantial number of the facets4062may have a non-uniform orientation. In one arrangement, a substantial number of the facets4062have a random orientation. In some embodiments, the facets4062bare non-uniform (e.g., random) in shape and are non-uniform (e.g., random) in orientation.

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.

FIG. 64shows another embodiment of a mask4200that is substantially similar to any of the masks hereinbefore described, except as set forth below. Also, the mask4200can be formed by any suitable process, such as those discussed below in connection withFIGS. 67a-67dand with variations of such processes. The mask4200includes a body4204. The body4204has an outer peripheral region4205, an inner peripheral region4206, and a hole region4207. The hole region4207is located between the outer peripheral region4205and the outer peripheral region4206. The body4204may also include an aperture region, where the aperture (discussed below) is not a through hole. The mask4200also includes a nutrient transport structure4216. In one embodiment, the nutrient transport structure includes a plurality of holes4220. At least a substantial portion of the holes4220(e.g., all of the holes) are located in the hole region4207. As above, only a portion of the nutrient structure4216is shown for simplicity. But it should be understood that the hole4220may be located through the hole region4207.

The outer peripheral region4205may extend from an outer periphery4224of the mask4200to a selected outer circumference4226of the mask4200. The selected outer circumference4225of the mask4200is located a selected radial distance from the outer periphery4224of the mask4200. In one embodiment, the selected outer circumference4225of the mask4200is located about 0.05 mm from the outer periphery4224of the mask4200.

The inner peripheral region4206may extend from an inner location, e.g., an inner periphery4226adjacent an aperture4228of the mask4200to a selected inner circumference4227of the mask4200. The selected inner circumference4227of the mask4200is located a selected radial distance from the inner periphery4226of the mask4200. In one embodiment, the selected inner circumference4227of the mask4200is located about 0.05 mm from the inner periphery4226.

The mask4200may be the product of a process that involves random selection of a plurality of locations and formation of holes on the mask4200corresponding 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 regions4205,4206. Another criterion prohibits all, at least a majority, or at least a substantial portion of the holes4220from 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 ofFIG. 64, the outer peripheral region4205is eliminated and the hole region4207extends from the inner peripheral region4206to an outer periphery4224. In another variation of the embodiment ofFIG. 64, the inner peripheral region4206is eliminated and the hole region4207extends from the outer peripheral region4205to an inner periphery4226.

FIG. 61Bshows a mask4300that is similar to the mask3000except as set forth below. The mask4300can be formed by any suitable process, such as those discussed below in connection withFIGS. 67a-67dand with variations of such processes. The mask4300includes a body4304that has an anterior surface4308and a posterior surface4312. The mask4300also includes a nutrient transport structure4316that, in one embodiment, includes a plurality of holes4320. The holes4320are formed in the body4304so that nutrient transport is provided but transmission of radiant energy (e.g., light) to the retinal locations adjacent the fovea through the holes4304is substantially prevented. In particular, the holes4304are formed such that when the eye with which the mask4300is coupled is directed at an object to be viewed, light conveying the image of that object that enters the holes4320cannot exit the holes along a path ending near the fovea.

In one embodiment, each of the holes4320has a hole entrance4360and a hole exit4364. Each of the holes4320extends along a transport axis4366. The transport axis4366is formed to substantially prevent propagation of light from the anterior surface4308to the posterior surface4312through the holes4320. In one embodiment, at least a substantial number of the holes4320have a size to the transport axis4366that is less than a thickness of the mask4300. In another embodiment, at least a substantial number of the holes4320have a longest dimension of a perimeter at least at one of the anterior or posterior surfaces4308,4312(e.g., a facet) that is less than a thickness of the mask4300. In some embodiments, the transport axis4366is formed at an angle with respect to a mask axis4336that substantially prevents propagation of light from the anterior surface4308to the posterior surface4312through the hole4320. In another embodiment, the transport axis4366of one or more holes4320is formed at an angle with respect to the mask axis4336that is large enough to prevent the projection of most of the hole entrance4360from overlapping the hole exit4364.

In one embodiment, the hole4320is circular in cross-section and has a diameter between about 0.5 micron and about 8 micron and the transport axis4366is between 5 and 85 degrees. The length of each of the holes4320(e.g., the distance between the anterior surface4308and the posterior surface4312) is between about 8 and about 92 micron. In another embodiment, the diameter of the holes4320is about 5 micron and the transport angle is about 40 degrees or more. As the length of the holes4320increases it may be desirable to include additional holes4320. In some cases, additional holes4320counteract the tendency of longer holes to reduce the amount of nutrient flow through the mask4300.

FIG. 61Cshows another embodiment of a mask4400similar to the mask3000, except as set forth below. The mask4400can be formed by any suitable process, such as those discussed below in connection withFIGS. 67a-67dand with variations of such processes. The mask4400includes a body4404that has an anterior surface4408, a first mask layer4410adjacent the anterior surface44008, a posterior surface4412, a second mask layer4414adjacent the posterior surface4412, and a third mask layer4415located between the first mask layer4410and the second mask layer4414. The mask4400also includes a nutrient transport structure4416that, in one embodiment, includes a plurality of holes4420. The holes4420are formed in the body4404so that nutrient are transported across the mask, as discussed above, but transmission of radiant energy (e.g., light) to retinal locations adjacent the fovea through the holes4404is substantially prevented. In particular, the holes4404are formed such that when the eye with which the mask4400is coupled is directed at an object to be viewed, light conveying the image of that object that enters the holes4420cannot exit the holes along a path ending near the fovea.

In one embodiment, at least one of the holes4420extends 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 mask4400includes a first hole portion4420athat extends along a first transport axis4466a, the second mask layer4414includes a second hole portion4420bextending along a second transport axis4466b, and the third mask layer4415includes a third hole portion4420cextending along a third transport axis4466c. The first, second, and third transport axes4466a,4466b,4466cpreferably are not collinear. In one embodiment, the first and second transport axes4466a,4466bare parallel but are off-set by a first selected amount. In one embodiment, the second and third transport axes4466b,4466care parallel but are off-set by a second selected amount. In the illustrated embodiment, each of the transport axes44466a,4466b,4466care off-set by one-half of the width of the hole portions4420a,4420b,4420c. Thus, the inner-most edge of the hole portion4420ais spaced from the axis4336by a distance that is equal to or greater than the distance of the outer-most edge of the hole portion4420bfrom the axis4336. This spacing substantially prevents light from passing through the holes4420from the anterior surface4408to the posterior surface4412.

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 portions4420a,4420b,4420cwith the desired off-set is to provide a layered structure. As discussed above, the mask4400may include the first layer4410, the second layer4414, and the third layer4415.FIG. 61Cshows that the mask4400can be formed with three layers. In another embodiment, the mask4400is formed of more than three layers. Providing more layers may advantageously further decrease the tendency of light to be transmitted through the holes4420onto the retina. This has the benefit of reducing the likelihood that a patient will observe or otherwise perceive a patter that will detract from the vision benefits of the mask4400. A further benefit is that less light will pass through the mask4400, thereby enhancing the depth of focus increase due to the pin-hole sized aperture formed therein.

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 withFIGS. 62B and 62C, various random patterns of holes may advantageously be provided for nutrient transport. In some embodiment, it may be sufficient to provide regular patterns that are non-uniform in some aspect. Non-uniform aspects to the holes may be provided by any suitable technique.

In a first step of one technique, a plurality of locations4020′ is generated. The locations4020′ are a series of coordinates that may comprise a non-uniform pattern or a regular pattern. The locations4020′ 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 locations4020′ 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 locations4020′ 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 locations3020′ ofFIG. 62A) is selected in the first step, the subset of locations may be moved with respect to their initial positions as selected in the first step. In one embodiment, each of the locations in the subset of locations is moved by an amount equal to a fraction of the hole spacing. For example, each of the locations in the subset of locations may be moved by an amount equal to one-quarter of the hole spacing. Where the subset of locations is moved by a constant amount, the locations that are moved preferably are randomly or pseudo-randomly selected. In another embodiment, the subset of location is moved by a random or a pseudo-random amount.

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 locations 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 system2000ofFIG. 55employs a marking module2024that provides a visual cue in the form of a projected image for a surgeon during a procedure for applying a mask. In addition, some techniques for treating a patient involve positioning an implant with the aid of a marked reference point. These methods are illustrated byFIGS. 65-66B.

In one method, a patient is treated by placing an implant5000in a cornea5004. A corneal flap5008is lifted to expose a surface in the cornea5004(e.g., an intracorneal surface). Any suitable tool or technique may be used to lift the corneal flap5008to expose a surface in the cornea5004. For example, a blade (e.g., a microkeratome), a laser or an electrosurgical tool could be used to form a corneal flap. A reference point5012on the cornea5004is identified. The reference point5012thereafter is marked in one technique, as discussed further below. The implant5000is positioned on the intracorneal surface. In one embodiment, the flap5008is then closed to cover at least a portion of the implant5000.

The surface of the cornea that is exposed is a stromal surface in one technique. The stromal surface may be on the corneal flap5008or on an exposed surface from which the corneal flap5008is removed.

The reference point5012may be identified in any suitable manner. For example, the alignment devices and methods described above may be used to identify the reference point5012. In one technique, identifying the reference point5012involves 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 point5012involves 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 flap5008in 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 flap5008is lifted and thereafter is laid on an adjacent surface5016of the cornea5004. In another technique, the corneal flap5008is laid on a removable support5020, such as a sponge. In one technique, the removable support has a surface5024that is configured to maintain the native curvature of the corneal flap5008.

FIG. 65shows that the marked reference point5012is helpful in positioning an implant on an intracorneal surface. In particular, the marked reference point5012enables the implant to be positioned with respect to the visual axis of the eye. In the illustrated embodiment, the implant5000is positioned so that a centerline of the implant, indicated as MCL, extends through the marked reference point5012.

FIG. 65Aillustrates another technique wherein a reference5012′ is a ring or other two dimensional mark. In such a case, the implant5000may be placed so that an outer edge of the implant and the ring correspond, e.g., such that the ring and the implant5000share the same or substantially the same center. Preferably, the ring and the implant5000are aligned so that the centerline of the implant MCLis on the line of sight of the eye, as discussed above. The ring is shown in dashed lines because in the illustrated technique, it is formed on the anterior surface of the corneal flap5008.

In one technique, the corneal flap5008is closed by returning the corneal flap5008to the cornea5004with the implant5000on the corneal flap5008. In another technique, the corneal flap5008is closed by returning the corneal flap5008to the cornea5004over the implant5000, which previously was placed on the tissue bed (the exposed intracorneal surface).

When the intracorneal surface is a stromal surface, the implant5000is placed on the stromal surface. At least a portion of the implant5000is covered. In some techniques, the implant5000is covered by returning a flap with the implant5000thereon to the cornea5004to 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 implant5000is performed.

After the flap5008is closed to cover at least a portion of the implant5000, the implant5000may be repositioned to some extent in some applications. In one technique, pressure is applied to the implant5000to move the implant into alignment with the reference point5012. The pressure may be applied to the anterior surface of the cornea5004proximate an edge of the implant5000(e.g., directly above, above and outside a projection of the outer periphery of the implant5000, or above and inside a projection of the outer periphery of the implant5000). 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 implant5000may be repositioned in this manner if the reference point5012was marked on the flap5008or if the reference point5012was marked on the tissue bed. Preferably, pushing is accomplished by inserting a thin tool under the flap or into the pocket and directly moving the inlay.

FIG. 66shows that a patient may also be treated by a method that positions an implant5100in a cornea5104, e.g., in a corneal pocket5108. Any suitable tool or technique may be used to create or form the corneal pocket5108. For example, a blade (e.g., a microkeratome), a laser, or an electrosurgical tool could be used to create or form a pocket in the cornea5104. A reference point5112is identified on the cornea5104. The reference point may be identified by any suitable technique, such as those discussed herein. The reference point5112is marked by any suitable technique, such as those discussed herein. The corneal pocket5108is created to expose an intracorneal surface5116. The corneal pocket5108may be created at any suitable depth, for example at a depth within a range of from about 50 microns to about 300 microns from the anterior surface of the cornea5104. The implant5100is positioned on the intracorneal surface5116. The marked reference point5112is helpful in positioning the implant5100on the intracorneal surface5116. The marked reference point5112enables the implant5100to be positioned with respect to the visual axis of the eye, as discussed above. In the illustrated embodiment, the implant5100is positioned so that a centerline MCLof the implant5100extends through or adjacent to the marked reference point5112.

FIG. 66Aillustrates another technique wherein a reference5112′ is a ring or other two dimensional mark. In such case, the implant5100may be placed so that an outer edge of the implant and the ring correspond, e.g., such that the ring and the implant5100share the same or substantially the same center. Preferably, the ring and the implant5100are aligned so that the centerline of the implant MCLis on the line of sight of the eye, as discussed above. The ring is shown in solid lines because in the illustrated embodiment, it is formed on the anterior surface of the cornea5104above the pocket5108.

After the implant5100is positioned in the pocket5108, the implant5100may be repositioned to some extent in some applications. In one technique, pressure is applied to the implant5100to move the implant into alignment with the reference point5112. The pressure may be applied to the anterior surface of the cornea5104proximate an edge of the implant5100(e.g., directly above, above and outside a projection of the outer periphery of the implant5100, or above and inside a projection of the outer periphery of the implant5100). This may cause the implant5100to move slightly away from the edge at which pressure is applied. In another technique, pressure is applied directly to the implant5100.

VII. Methods of Making an Ocular Implant

A variety of techniques can be used to make masks that have desirable performance characteristics and that can correct presbyopia and other vision defects in patients. As discussed above, it is desirable that the mask be at least partially opaque to visible light and UV stable for some applications. Also, the masks should be sufficiently biocompatible that the mask can reside adjacent or within eye tissue without harming the tissue. The masks also should be relatively thin so that they are capable of being implanted in a thin ocular structure, such as the cornea. Such performance characteristics are largely a function of the material of which the masks are comprised, mask design, and manufacturing technique. Applicants have discovered that some metals are among the materials that can be configured to exhibit these characteristics and that processes that form thin films (e.g., thin films of metal) are well suited for making such ocular implants. Physical vapor deposition, sputtering, and other similar processes discussed herein are particularly well suited for making ocular implants of thin films.

Additionally, applicants have discovered that these processes and methods can be combined with other methods and structures described herein to make a mask or implant that performs well. For example, the methods described below can be combined with techniques discussed above, such as techniques for forming nutrient transport structures. In one method the mask that is formed is a thin, micro-perforated, corneal implant that is bio-compatible and corrosion resistant in the human eye. The mask is of a shape analogous to a washer, e.g., an annulus defined between an inner periphery and an outer periphery. The mask can have an inner diameter of about 1.5 mm, an outer diameter of about 4 mm, and conform to a portion of the surface of a sphere having a radius of curvature of about 8 mm. The curvature of the mask can vary, but it is generally selected to conform to the curvature of an anatomical feature, e.g., the cornea of an adult human eye. The radius of curvature of the mask can be within a range of from about 7.8 mm to about 8.2 mm in some embodiments. The radius of curvature of the mask can be within a range of from about 7.6 mm to about 8.4 mm in other embodiments. The radius of curvature of the mask can be within a range of from about 7.4 mm to about 8.6 mm in other embodiments. The radius of curvature of the mask can be within a range of from about 7.2 mm to about 8.8 mm in other embodiments. The radius of curvature of the mask can be within a range of from about 7 mm to about 9 mm in other embodiments. In some embodiments, the radius of curvature of the mask can be less than 7 mm. In other embodiments, the radius of curvature of the mask can be more than 9 mm. In one technique, the mask has approximately 1000-3000 micro-perforations extending between a first, e.g., convex, surface and a second, e.g., concave, surface of the mask, that have a transverse dimension of on average between about 10 microns and about 25 microns. The mask can have a thickness between the convex and concave surface of about 10 microns or less or about 7 microns or less. The dimensions listed in this paragraph are of one example. Other dimensions and features discussed elsewhere herein could be substituted for or added to the dimensions discussed in this paragraph. The color of the mask is cosmetically acceptable in one embodiment for implantation in the human cornea, e.g., having a black or a dark color appearance at least on an anterior (convex) side of the annulus.

A. Forming a Mask Using Physical Vapor Deposition

FIGS. 67a-67dillustrate techniques that can be used to form a mask or an implant for treating presbyopia, such as one similar to the masks and implants discussed herein. These techniques involve forming layers of material, at least one of which is configured for application to a human eye. As discussed below, the layers of material can include any combination of one or more of a release layer, a mask layer, and a sacrificial layer. As used herein, the term “sacrificial layer” is a broad term used in its ordinary sense and includes any layer that is formed during a method for making a mask that is primarily or entirely to facilitate other aspects of the method of making and also includes layers that are entirely or substantially removed during the process or are not part of the mask. A “release layer” is a type of sacrificial layer that is intended to facilitate separating one structure from another, e.g., to separate a mask from a substrate, as discussed below. Any suitable technique for forming the layers of material can be exploited. Techniques for forming layers using thin film sputtering are discussed first. Other techniques that can be used are discussed thereafter.

1. Thin Film Sputtering

The applicants have discovered that thin film sputtering is a convenient technique for making a mask that is capable of being implanted in a human eye for treating presbyopia. Thin film sputtering is particularly well suited for making a corneal inlay. Many thin film sputtering techniques include three steps: 1) generating atomic or ionic species from a target comprising a metal or an alloy material; 2) transporting the species from the target to a substrate through a gas or a plasma medium; and 3) condensing the species on a surface of a substrate to form a solid thin film. As discussed below, Argon gas can be used to generate a plasma to enable these process steps. The target can comprise any metal or metal alloy and the substrate can comprise a polished silicon or glass wafer or a wafer of another suitable material. In one technique, a non-planar substrate is used to form one or more mask layer, release layer, or sacrificial layer. In another embodiment, a planar substrate is used to form a layer.

FIG. 67ais a cross-sectional view of a portion of a substrate6000that can be used in a sputtering process to form a mask or other thin ocular implant. The substrate6000is provided with a top surface6004that includes a mask forming feature6008. In one embodiment, the substrate6000also includes a planar portion6012that at least partially surrounds the mask forming feature6008. The planar portion6012is a region of the substrate6000that can be located between adjacent mask forming features. Although adjacent mask forming features are not shown, such features can be located at regular or non-regular intervals across the substrate6000. The substrate6000can be configured with any number of mask forming features6008that will fit on the substrate6000. For example, in some methods, it is advantageous to form one or two mask forming features6008on a substrate. In other embodiments, it is advantageous to form at least four mask forming features6008on a substrate. Depending on the size of the substrate and the techniques used, four or more than four mask forming features6008could be formed on a substrate. Other techniques permit sixteen, thirty-two, sixty-four or more mask forming features6008to be formed on a substrate. In a four inch square substrate, as many as one-hundred-forty-four or more mask forming features6008could be formed on the substrate. The arrangement of adjacent mask forming features could use any packing method, e.g., similar to an efficient crystal packing arrangement.

The mask forming feature6008can be configured such that later process steps produce a mask shaped to conform to the portion of the ocular anatomy where the mask is to be implanted. For example, the mask forming feature6008can comprise a curved profile6016that corresponds to the curvature of a layer of the cornea, or other ocular feature. In one embodiment, the mask forming feature6008includes an annular surface6020that surrounds a central axis6024. In the technique illustrated inFIGS. 67a-67d, the annular surface6020is substantially smooth, resulting in the formation of a smooth layer, e.g., one without discontinuities, pores, or apertures within the boundaries of the annular surface6020. In other embodiments, the annular surface6020is configured to produce micro-perforations, pores, or holes, that form at least a part of a nutrient transport structure similar to those discussed herein. In other embodiments, the annular surface6020is configured to produce a desired surface condition of a mask formed thereon that correlates to a desired blending characteristic. The mask forming feature6008also includes a central region6028which is centered on the central axis6024in one embodiment.

FIG. 67ashows the profile of the annular surface6020at a section plane that extends through the center of the mask forming feature6008and that includes the central axis6024. The profile of the annular surface6020includes a first curved profile6016aand a second curved profile6016b. The first and second curved profiles6016a,6016bhave generally the same arcuate length and curvature in one embodiment. The annular surface6020can be configured to form micro-perforations or pores that form at least a part of a nutrient transport structure. For example, the profiles6016a,6016bcan include a nutrient transport forming feature, such as one or more discontinuities, depressions, holes, or wells, that are configured to prevent or substantially prevent bridging across the nutrient transport forming feature in a layer formed above the profiles. In this context, “substantially prevent” means that any bridging that occurs across the nutrient transport forming feature is removable by a later process that will not damage the layer near the feature.

In one technique, holes are provided that have a diameter selected to provide an appropriate aspect ratio for nutrient transport features in the mask. For example, the diameter of the holes can be any diameter that provides a ratio of hole size (e.g., diameter) divided by layer thickness that is greater than one. In another technique, the diameter of the holes is selected to provide a ratio of hole size (e.g., diameter) divided by layer thickness that is about one. Nutrient transport structures can be formed in other ways, e.g., using photolithography, as discussed below.

The annular surface6020can be configured to form a mask with an anterior surface having a selected surface condition. For example, one technique produces a mask with a surface roughness that produces a desired blending characteristic. A blending characteristic is a characteristic that makes an implant partially or completely non-observable by others. Some materials that can be used in the techniques discussed below to form a mask from one or more layers of thin metal can be made to appear darker by increasing the roughness of a surface that is visible when the mask is implanted, e.g., the anterior surface. The roughness of an anterior surface of a mask can be increased by increasing the roughness of the annular surface6020.

The mask forming feature6008can be configured to define one or more edges of a mask formed on the annular surface6020in a later process stage. In one embodiment, the annular surface6020has an inner periphery6032and an outer periphery6036. The inner and outer periphery6032,6036of the annular surface6020correspond to an inner and an outer periphery of a mask formed on the annular surface6020in a later process stage.

In one embodiment, the inner periphery6032is a substantially circular periphery. In one embodiment, the outer periphery6036is a substantially circular periphery. In one embodiment, both the inner and outer periphery6032,6036are substantially circular and are centered on the central axis6024. In some embodiments, the inner and outer peripheries6032,6036have different shapes, e.g., a circular inner periphery and a non-circular outer periphery, a non-circular inner periphery and a circular outer periphery, etc. In another embodiment, at least one of the inner and outer periphery6032,6036is not centered on the central axis6024. For example, in one embodiment, the inner and outer periphery are circular but at least one of the inner and outer periphery6032,6036is not centered on the central axis6024. As a result, the annular surface6020(and the mask formed thereon at a later stage) can be asymmetrical about the central axis6024in some embodiments. The inner and outer periphery6032,6036can have other configurations such that the annular surface6020(and the mask formed thereon at a later stage) has other shapes. Other shapes for the annular surface6020that correspond to the mask designs described herein can be provided.

The substrate6000can comprise a wafer of silicon, a glass or pyrex slide, a wafer of ceramic material, or any other suitable material or arrangement. The size of the substrate6000is not critical, and can be any size practical for processing through a sputter process chamber. A typical circular substrate wafer size is 4″ diameter, though other sizes can be used.

In one embodiment, the mask forming feature6008includes an annular inner recess6040and an annular outer recess6044formed in the substrate6000. The inner recess6040is a U-shaped well or channel having a transverse dimension that extends from the inner periphery6032of the annular surface6020toward the central axis6024in one embodiment. The outer recess6044is a U-shaped well or channel having a transverse dimension that extends from the outer periphery6036of the annular surface6020away from the central axis6024in one embodiment. The inner recess6040and outer recess6044may be formed in any of a variety of ways such as mechanical grinding or chemical etching.

The width and the depth of the inner and outer recesses6040,6044are selected to be large enough to prevent material layers formed in later stages from bridging or extending across the recesses6040,6044. One technique for preventing bridging is to provide that the width of the recesses6040,6044is approximately equal to the thickness of a layer to be formed on the substrate6000. Another technique for preventing bridging is to provide that the width of the recesses6040,6044is greater than the thickness of a layer to be formed on the substrate6000. The inner and outer recesses6040,6044enable layers of material to be deposited on the substrate6000in the desired shape, e.g., defining the inner and outer periphery of a mask at a later stage. This arrangement enables a mask to be deposited (formed) substantially in the same shape in which it is to be implanted. This advantageously eliminates later process steps of defining the inner and outer periphery of the mask. Other processes described below employ additional steps to define at least one aspect of a mask, e.g., its inner or outer periphery or curvature.

The dimensions of the inner and outer periphery6032,6036and the curvature of the first and second curved profiles6016a,6016bpreferably are selected to correspond to the inner and outer dimensions and the curvature of a mask respectively. These dimensions are discussed above in connection with the various masks described herein. In one embodiment, the inner and outer periphery6032,6036of the mask forming feature6008have the same dimensions as a mask to be formed thereon and the curvature of the first and second curved profiles6016a,6016bare the same as the desired curvature of the mask to be formed thereon.

In one embodiment, the mask forming feature6008protrudes from the top surface6004of the substrate6000. In this arrangement, the mask forming feature6008presents a convex surface upon which a material layer may be formed. As discussed below, a release layer, a mask layer, a sacrificial layer, or another material layer may be formed on the convex surface of the mask forming feature6008or on a layer of material formed on the convex surface.FIG. 67ashows that in one embodiment, the first and second curved profiles6016a,6016bare convex curved profiles.

In one variation, a mask is initially formed in a flat configuration on a planar top surface of a substrate that is otherwise similar to the substrate6000. This variation may be used to form a mask that is sufficiently flexible to conform to an ocular structure, e.g., a corneal layer, when applied to the structure, and thus does not require any preformed shape. In some techniques, one or more further steps are performed (such as thermoforming or compression, depending upon the mask material) to shape the mask to conform to an ocular structure after the mask is formed on the planar top surface.

In one variation of the mask forming feature6008, a continuous imperforate curved profile is provided by eliminating the inner recess6040. As discussed further below, this arrangement could be used in a process wherein an inner periphery of a mask is defined after sputtering. The inner periphery of a mask can be defined by cutting a central region out of the mask. Any suitable technique can be used to cut out the central region. For example, the central region could be cut out by a laser cutting process. Laser cutting can be used to otherwise further define a mask, e.g., by separating a mask from a neighboring mask or by forming nutrient transport apertures in a portion of a mask.

In another variation, the mask forming feature6008includes a concave surface upon which a mask can be formed. In this arrangement, the mask forming feature6008includes a recess in the top surface6004of the substrate6000. As discussed further below, a mask can be formed on the substrate6000with one surface of the mask exposed, e.g., with one surface of the mask not in contact with the substrate6000or with any layer between the substrate6000and the mask.

The substrate6000can be prepared using any technique that will facilitate the formation of thin film layers thereon. For example, the top surface6004can be cleaned and polished to facilitate sputtering processes, as described below, or other mask forming processes. In one technique, the substrate6000is cleaned at an elevated temperature using a cleaning solution or agent for a fixed period. For example, the substrate6000can be cleaned in an RCA cleaning solution (e.g., a mixture of ammonium hydroxide, hydrogen peroxide and DI water in the ratio of 1:1:5 respectively) at 80 degrees Celsius for 30 minutes to remove impurities such as grease and dust particles. Alternatively, other cleaning solutions can be used, such as Micro-90 (a commercially available mixture of salts of sodium, ammonium and acids). In another technique, discussed above, the substrate600is prepared by providing a roughness level that is selected to provide a desired blending characteristic.

As discussed above, sputtering is an advantageous method of forming thin layers of material on a substrate for forming an ocular implant. Sputtering is usually performed in a vacuum or very low pressure and so a process chamber is normally provided in which the substrate6000can be mounted. In one technique, the substrate6000is mounted on a table that is rotated during the process. Rotation of the substrate results in a more uniform deposition of material, providing a more uniform thickness, for example. The process chamber preferably also is configured to receive a target comprising a target material. In some arrangements, the process chamber is capable of accommodating multiple targets so that different materials can be sputtered, if needed. Preferably the process chamber is capable of multiple sputtering modes, for example enabling sputtering from one or all the targets in one or both of a radio frequency (RF) sputtering mode and a direct current (DC) sputtering mode.

In one sputtering technique, a vacuum in the range of low 10−7torr is induced in the process chamber by one or more vacuum pumps, which can be a mechanical pump, cryo pump or turbo molecular pump. Argon gas (or other inert gas) at a low pressure (around a few millitorr) is introduced into the chamber. Thereafter a high voltage from a DC or an RF power supply is applied to the target material to create a glow discharge. The glow discharge dissociates the argon atoms into a cloud of ions called a plasma. The ions in the plasma can be accelerated toward the target material. Collision of the ions with the target causes atoms of the target material to be dislodged from the surface of the target. Thereafter, the dislodged atoms condense on the exposed surfaces of the substrate6000. As the amount of atoms that are condensed on the substrate6000increases, a thin film of the material forms on the substrate6000.

FIG. 67billustrates a later stage of a method for making a mask in which a release layer6080has been formed on the mask forming feature6008of the substrate6000. As discussed above, a release layer is a type of sacrificial layer that facilitates the separation of a mask from the substrate6000. The release layer6080can be formed using the sputtering process described above or any suitable variation thereof. In one technique, the release layer6080is formed by using a target comprised of a material that can be eroded away by another process, e.g., by etching, without damaging other layers that form a part of or are coupled with a mask. The material used to form the release layer6080may be a metal, such as chromium, aluminum, copper, TiCuAg, 90% tungsten 10% titanium (released with hydrogen peroxide), or any other metal or alloy. Other materials can be used if the release layer is to enable separation of mask layers from the substrate6000by a non-erosion process.

In one embodiment, the release layer6080is sputter deposited to a thickness of about 500 Å or more on the substrate6000. The release layer6080can be sputter deposited using RF sputtering at argon pressure of about 2 millitorr. The thickness of the release layer6080can vary. For example, the release layer could have a thickness of a few hundred angstroms, a thickness less than 500 Å, a thickness of more than about 500 Å, a thickness of a thousand angstroms, or more.

FIG. 67bshows that the arrangement of the mask forming feature6008prevents the release layer6080from bridging from the planar portion6012to the annular surface6020and from the annular surface6020to the central region6028. This aspect of the mask forming feature6008facilitates separation of a mask formed at a later stage of the process from the substrate6000because the mask can be released from the inner periphery and from the outer periphery of the mask forming feature6008. In some techniques, the planar portion6012, annular surface6020, and central region6028are not fully isolated from each other and the process for separating the mask from the mask forming feature6008operates primarily from one of the inner periphery6032and the outer periphery6036.

FIG. 67cshows that after the release layer6080is formed on the substrate6000, a mask layer6100can be formed on the release layer6080.FIG. 67cshould not be taken to suggest that no other process steps are performed between formation of the release layer6080and the mask layer6100. For example, in some techniques, the release layer6080is modified prior to formation of the mask layer6100. It may be desirable to modify the release layer6080so that it has a desired thickness, e.g., by removing a portion of the release layer6080. For example, the average thickness of the release layer6080could be reduced across the entire mask forming feature6008. In another example, the thickness of the release layer6080could be reduced at a selected location of the mask forming feature6008. The mask layer6100can be formed by any suitable technique, such as one of the sputtering processes discussed above or a variation thereof.

In one technique, a mask for treating an ocular ailment, such as presbyopia or an aberration, is entirely or substantially entirely formed by a sputtering or other vapor deposition process. As used in this context, “substantially entirely formed” means that a least the entire thickness of the mask is formed by this process and that further steps do not add thickness to the mask, but may reduce the thickness, form cutouts in the mask, and form the mask. As discussed further below, in one variation, the mask layer6100can be a layer configured to facilitate handling of a mask formed by the processes described herein or to facilitate application of such a mask to an eye of a patient.

In one technique, the mask is substantially entirely formed by the process, e.g., the mask layer6100forms the mask. In this technique, the mask layer6100preferably is able to substantially improve the patient's vision. The mask layer6100preferably is made to be at least partially opaque. The mask layer6100preferably is sufficiently stable to environmental conditions, such as UV radiation. The mask layer6100preferably is sufficiently biocompatible so that it can be implanted in an eye of a human. A variety of metals have these properties and are capable of being formed as thin structures that can be applied to the eye, e.g., as corneal inlays. For example, nitinol or TiNi and other derivative alloys of TiNi, gold, tantalum, platinum, titanium (e.g., titanium6aluminum4vanadium), and stainless steel are believed to have these properties and to be able to perform well in ocular applications. The mask layer6100can be formed of any of these materials.

As discussed above, a process chamber can be provided with multiple targets, e.g., one for a mask layer and another for a release layer. In another technique, the release layer6080and the mask layer6100are formed using different modes of the chamber. For example, the mask layer6100can be sputtered using DC sputtering and the release layer6080using RF sputtering. A mask layer comprising an alloy material can be sputtered from a single alloy target or by co-sputtering from multiple targets. In another technique, the mask layer6100and the release layer6080are sputtered in separate chambers.

In one technique, the substrate6000is loaded into a process chamber and a vacuum is induced in the chamber in a low 10−7torr range. After the release layer6080is formed on the substrate6000, the mask layer6100is sputter deposited on top of the release layer6080using DC sputtering at an argon pressure of about 2 millitorr. The mask layer6100can be sputtered to any desirable thickness, e.g., any of the thicknesses of the mask3000discussed above.

Other deposition techniques that may be used to form a mask layer, a release layer, or a sacrificial layer include vapor deposition, vacuum evaporation, molecular beam epitaxy, evaporative deposition, pulsed laser deposition, ion plating, ion implantation, and laser surface alloying. Other types of vapor deposition and other techniques for forming layers are discussed below.

FIG. 67dillustrates a technique for separating a mask6200formed by the process discussed in connection withFIGS. 67a-67cfrom a substrate6000. As discussed above, the release layer6080is a sacrificial layer, e.g., a layer that facilitates the formation of the mask6200and that is substantially or entirely removed from the mask6200during the process of making the mask6200. The mask6200may be separated from the substrate6000by any suitable technique. In one technique, the release layer6080is eroded away so that a gap forms between the annular surface6020and the mask6200. When the release layer6080is fully eroded, the mask6200is entirely separated from the substrate6000. As discussed above, the inner and outer recesses6040,6044enable the process of eroding the release layer6080to proceed from both sides of the annular surface6020. This may significantly shorten the process time for separating the mask6200from the substrate6000.

In one technique, the substrate6000with the release and mask layers6080,6100formed thereon is immersed in a bath containing an agent capable of eroding the release layer6080, as discussed above. The agent may be a chemical that will selectively etch the release layer6080but have no harmful effect on the mask layer6100. Preferably, the etchant or other chemical or agent used to release the layer6100from the substrate6000does not react strongly with the layer6100. In one technique, the release layer6080is formed of chromium and the mask is separated from the substrate by contacting the release layer6080with a chromium etchant. For example, the chromium release layer can be submerged in a chromium etching bath. Although chromium and other release layer material have been discussed herein, one skilled in the art will recognize that a wide variety of materials could be used as a release layer and an agent for separating a device layer from a substrate.

FIG. 67dshows that separating the mask6200from the substrate6000generates one or more pieces of scrap material6204, which may correspond to material deposited at the same time as the mask layer6100. These scrap pieces are separated from the mask6200and are discarded. The scrap material6204is separated from the mask6200and discarded.

Another optional step that may be performed at any stage during or after the formation of the mask layer6080comprises configuring an anterior surface of the mask6200, e.g., the convex surface of the mask6200, to have a blending characteristic that provides a discrete appearance. For example, when a shiny metallic material is used to form the mask layer6100, it may be desirable to darken the anterior surface of the mask6200. The anterior surface may be darkened by applying a carbon coating to the anterior surface. Carbon is particularly well suited for masks that are made of metals other than nitinol. In another technique, the anterior surface of the mask6200is darkened by treating the surface. One surface treatment that could be provided is a treatment that roughens the surface of the mask6200, e.g., raises its RMS roughness measure. In another technique, the roughness of the surface of the mask6200is increased by increasing the roughness of the annular surface6020of the substrate6000. In some techniques, it may be desirable to darken both the anterior and posterior surfaces of the mask6200.

The process ofFIGS. 67a-67denables a mask to be formed in substantially the same configuration in which it is to be implanted in the eye of a patient. As discussed above, this is achieved in part by providing a substrate with a mask forming feature that is shaped to correspond to the shape of the ocular anatomy in the region of the eye where the mask is to be applied. This may be achieved by providing the mask forming feature with a shape that is similar to the shape of a layer of corneal tissue where the mask is to be implanted in the corneal. The process also facilitates application of the mask to the human eye by being capable of producing the mask with certain dimensions tightly controlled. For example, the process enables a mask to be formed that is thin enough to be implanted in the cornea without adversely affecting the adjacent corneal tissue.

As discussed above, one variation of the forgoing method of making a mask employs a substrate that is similar to the substrate6000but that is substantially planar rather than shaped. This process will form a mask that is similar to the mask6200, but that also initially is substantially planar. In some applications, a substantially planar mask6200may be thin enough to be applied to an eye and to conform to the native anatomy, e.g., to the curvature of the cornea, when applied. In other applications, it may be desirable to induce a permanent shape in a mask that was initially of a planar construction. As used in this context, “induce a permanent shape” is a broad term and it is used in its ordinary meaning and it includes forming the mask to retain its shape in the absence of a force other than gravity. This shape does not prevent the mask from flexing to an extent when applied to the eye or when acted on by ocular structures.

Any suitable process can be used to induce a shape in a mask. One such process involves placing the mask on or in a mandrel, engaging the mask with a member to cause it to take on the desired shape, and heat treating the mask to cause it to maintain that shape. This process is discussed in more detail in U.S. Pat. No. 6,746,890, which is hereby expressly incorporated by reference herein in its entirety.

As discussed above some masks are configured with nutrient transport structures that increase the acceptance of the mask by adjacent tissue. For example, the mask4400is formed with holes that extend from an anterior surface to a posterior surface. Such holes may be formed by depositing a plurality of layers with holes formed in them. The location of the holes in adjacent layers can be important, as discussed above. For example, the location of holes can reduce the production of diffraction patterns. The configuration and location and orientation of the holes can be adequately controlled using sacrificial layers and photolithography, as is discussed in more detail in U.S. Pat. No. 6,746,890, which is incorporated by reference herein above. Holes, sometimes referred to herein as “micro-perforations” or “perforations”, can also be formed in a process that provides a substrate with nutrient transport forming features, as discussed above.

As discussed above, one variation of the foregoing process provides a mask structure that enables a mask to be handled, e.g., while being manufactured, shipped, or applied by a surgeon to the patient's eye. As discussed above, some embodiments of masks configured to be applied to an eye are very thin. Stated another way, the structures have a relatively high ratio of surface area to thickness. This is particularly true where the mask is intended to be implanted in the cornea of a patient's eye. As a result, a thin mask can be damaged depending on the skill of the person handling it. Damage to the mask can include contamination on the surface of the mask, creases formed in the mask, etc. Such damage at least increases the processing time (e.g., by requiring additional cleaning steps) but can also require that the damaged mask be scrapped. To reduce the likelihood of scrapping of masks, it is desirable to provide a handling structure, e.g., a layer that is less easily damaged or that can be damaged without impairing the performance of the mask.

In one technique, a handling structure is formed as a removable mask support layer. The handling structure can be formed by any process. For example, any of the sputtering processes described above could be used to form the handling structure. In one embodiment, the handling structure is formed as a sacrificial layer. As discussed above, a sacrificial layer is a layer that can be removed or separated from the mask at some point during the lifecycle of the mask. The sacrificial handling layer can be made of the same material as the release layer6080, the same material as the mask layer6100, or another suitable material. The handling structure can be removed by any process, e.g., by eroding or etching the layer, or by otherwise separating the handling structure from the mask. The handling structure can take any suitable configuration. Preferably the handling structure is temporarily coupled with the mask or a portion thereof. For example, the handling structure can be coupled with an outer periphery of a mask. In one embodiment, the handling structure is an annular member that surrounds or partially surrounds the mask or a portion of the mask. The handling structure could be a bar or a flange of suitable configuration. The handling structure is configured to be clamped or fixed in a processing device or process chamber in one embodiment. The handling structure is able to securely hold a mask during one or more process steps in one embodiment. The handling structure is removable after the process for manufacturing the mask is complete or partially complete in one embodiment.

B. Forming a Mask Using Other Layer Forming Methods

Other techniques that do not involve sputtering to form a mask layer can be employed in other techniques or combined with methods involving physical vapor deposition.

1. Chemical Vapor Deposition

Chemical Vapor Deposition (CVD) may also be used to form the mask or a portion of the mask. CVD methods include atmospheric pressure chemical vapor deposition, low pressure chemical vapor deposition, plasma assisted (enhanced) chemical vapor deposition, photochemical vapor deposition, laser chemical vapor deposition, metal-organic chemical vapor deposition, and chemical beam epitaxy.

2. Precipitation Out of a Solution

A layer, such as a mask layer, release layer, or sacrificial layer, could be formed by precipitating a material out of a solution. This technique is analogous to the methods discussed above in connection withFIGS. 67a-67d, except as set forth below.

Mask layers, release layers, sacrificial layers, or other layers are formed by a precipitate that emerges from a solution. For example, a solution including metal ions can be prepared and placed into contact with a substrate. The substrate can be similar to the substrate6000. In one technique a tank is provided and the substrate is placed in the bottom of the tank. A solution with metal or alloy ions or molecules is then placed in the tank in contact with the substrate. Thereafter, the solution can be acted on to cause a metal or alloy ion or molecule to no longer be soluble in the solution. For example, sufficient quantities of the desired metal ion can be added to the solution such that the solubility of that ion within the solution is exceeded. This condition will cause the metal ion to precipitate out of the solution and condense onto the substrate6000. In another example, the solvent can be evaporated from the solution, increasing the concentration of the desired metal ion until its solubility is exceeded, thus causing the ion to precipitate out of the solution and to condense onto the substrate6000. Other techniques, such as altering the pH of the solution can be employed to get the solute to precipitate out of the solution.

Once sufficient solute has formed on the substrate, the solution can be evacuated from the tank and another solution placed in the tank with the same or a different material or metal ion solute. In some methods, more than one technique can be combined, such as using precipitation out of a solution for one layer and vapor deposition for another layer.

Other suitable techniques for forming layers that can be used to form some masks include electroplating or electrodepositing and electroforming. In one embodiment, forming a mask by electrodeposition is analogous to the method discussed above, except as set forth below.

Electrodeposition is the process of producing a layer or coating, which can be metallic, on a surface of an object by the action of electric current. The deposition of a metallic coating onto an object can be achieved by negatively charging the object to be coated and immersing the object into a solution that contains a salt of the metal to be deposited. In this arrangement, the object to be plated can be the cathode of an electrolytic cell. In one technique, the object to be plated is similar to the substrate6000.

In one technique, the metallic ions of the salt carry a positive charge and are attracted to the substrate or object. When the metallic ions reach the negatively charged object, e.g., a substrate, the substrate provides electrons to reduce the positively charged ions to metallic form. In electrodepositing and electroforming, the substrate can be made of any suitable material, e.g., copper. The material to be plated is one that can be eroded to separate a mask from the substrate, as discussed above, or a mask layer. Where the material to be plated is intended to be a mask layer, the material is selected with the biocompatility and stability properties discussed above for long implantation life (e.g., it is opaque, inert, and does not degrade in the presence of UV radiation).

In one technique, a conductor is coupled with the substrate or other object and with a negative pole of a battery (or other power supply). Another conductor is connected with a positive pole of the battery (or other power supply) and with an anode of the electrolytic cell. The anode is analogous to the target, discussed above in connection with sputtering. Thereafter, a cell is filled with a solution of the metal salt to be plated. The cell can be a process chamber. It is possible to use a molten salt (e.g., when plating tungsten and other similar materials). In some techniques, the salt is dissolved in water.

As the substrate or other object to be plated is negatively charged, it attracts the positively charged cations from the solution, and electrons flow from the substrate or other object to the cations to neutralize them (to reduce them) to metallic form. Meanwhile, negatively charged anions in the solution are attracted to the positively charged anode. At the anode electrons are removed from the anode material, oxidizing it to the anode cations. Thus we see that the anode (analogous to the target, as discussed above) dissolves as ions into the solution. That is how replacement cations of the anode/target material are supplied to the solution for that which has been plated out and one retains a solution of appropriate composition in the cell.

One advantage of this technique is that it may be able to make a porous structure that would at least partially provide nutrient transport through the mask, as discussed above, without further process steps. Additional nutrient transport could be provided by forming additional nutrient transport structures in the mask using any of the techniques discussed above.