Patent Publication Number: US-6221067-B1

Title: Corneal modification via implantation

Description:
RELATED APPLICATIONS 
     This application is related to applicant&#39;s application Ser. No. 07/844,879, filed Mar. 3, 1992, which is a continuation of application Ser. No. 07/425,928, filed Oct. 24, 1989, now abandoned, which is a continuation-in-part of application Ser. No. 07/370,095, filed Jun. 22, 1989, now abandoned, which is a continuation of application Ser. No. 07/221,011, filed Jul. 18, 1988, now abandoned, which is a continuation of application Ser. No. 06/866,302, filed May 23, 1986, now abandoned, which is a division of application Ser. No. 06/760,080, filed Jul. 29, 1985, now abandoned. 
    
    
     FIELD OF THE INVENTION 
     The invention relates to a method and apparatus for modifying a live cornea via injecting or implanting optical material in the cornea. In particular, the live cornea is modified by the steps of separating an internal area of the live cornea into first and second opposed radially directed internal surfaces, introducing transparent optical material between the surfaces and then recombining the first and second internal surfaces. 
     BACKGROUND OF THE INVENTION 
     In an ametropic human eye, the far point, i.e., infinity, is focused on the retina. Ametropia results when the far point is projected either in front of the retina, i.e., myopia, or in the back of this structure, i.e., hypermetropic or hyperopic state. 
     In a myopic eye, either the axial length of the eye is longer than in a normal eye, or the refractive power of the cornea and the lens is stronger than in ametropic eyes. In contrast, in hypermetropic eyes the axial length may be shorter than normal or the refractive power of the cornea and lens is less than in a normal eye. Myopia begins generally at the age of 5-10 and progresses up to the age of 20-25. High myopia greater than 6 diopter is seen in 1-2% of the general population. The incidence of low myopia of 1-3 diopter can be up to 10% of the population. 
     The incidence of hypermetropic eye is not known. Generally, all eyes are hypermetropic at birth and then gradually the refractive power of the eye increases to normal levels by the age of 15. However, a hypermetropic condition is produced when the crystalline natural lens is removed because of a cataract. 
     Correction of myopia is achieved by placing a minus or concave lens in front of the eye, in the form of glasses or contact lenses to decrease the refractive power of the eye. The hypermetropic eye can be corrected with a plus or convex set of glasses or contact lenses. When hypermetropia is produced because of cataract extraction, i.e., removal of the natural crystalline lens, one can place a plastic lens implant in the eye, known as an intraocular lens implantation, to replace the removed natural crystalline lens. 
     Surgical attempts to correct myopic ametropia dates back to 1953 when Sato tried to flatten the corneal curvature by performing radial cuts in the periphery of a corneal stroma (Sato, Am. J. Ophthalmol. 36:823, 1953). Later, Fyoderov (Ann. Ophthalmol. 11:1185, 1979) modified the procedure to prevent postoperative complications due to such radial keratotomy. This procedure is now accepted for correction of low myopia for up to 4 diopter (See Schachar [eds] Radial Keratotomy LAL, Pub. Denison, Tex., 1980 and Sanders D [ed] Radial Keratotomy, Thorofare, N.J., Slack publication, 1984). 
     Another method of correcting myopic ametropia is by lathe cutting of a frozen lamellar corneal graft, known as myopic keratomileusis. This technique may be employed when myopia is greater than 6 diopter and not greater than 18 diopter. The technique involves cutting a partial thickness of the cornea, about 0.26-0.32 mm, with a microkeratome (Barraquer, Ophthalmology Rochester 88:701, 1981). This cut portion of the cornea is then placed in a cryolathe and its surface modified. This is achieved by cutting into the corneal parenchyma using a computerized system. Prior to the cutting, the corneal specimen is frozen to −18° F. The difficulty in this procedure exists in regard to the exact centering of the head and tool bit to accomplish the lathing cut. It must be repeatedly checked and the temperature of the head and tool bit must be exactly the same during lathing. For this purpose, carbon dioxide gas plus fluid is used. However, the adiabatic release of gas over the carbon dioxide liquid may liberate solid carbon dioxide particles, causing blockage of the nozzle and inadequate cooling. 
     The curvature of the corneal lamella and its increment due to freezing must also be calculated using a computer and a calculator. If the corneal lamella is too thin, this results in a small optical zone and a subsequent unsatisfactory correction. If the tissue is thicker than the tool bit, it will not meet at the calculated surface resulting in an overcorrection. 
     In addition, a meticulous thawing technique has to be adhered to. The complications of thawing will influence postoperative corneal lenses. These include dense or opaque interfaces between the corneal lamella and the host. The stroma of the resected cornea may also become opaque (Binder Arch Ophthalmol 100:101, 1982 and Jacobiec, Ophthalmology [Rochester] 88:1251, 1981; and Krumeich J H, Arch, AOO, 1981). There are also wide variations in postoperative uncorrected visual acuity. Because of these difficulties, not many cases of myopic keratomileusis are performed in the United States. 
     Surgical correction of hypermetropic keratomycosis involves the lamellar cornea as described for myopic keratomileusis. The surface of the cornea is lathe cut after freezing to achieve higher refractive power. This procedure is also infrequently performed in the United States because of the technical difficulties and has the greatest potential for lathing errors. Many ophthalmologists prefer instead an alternative technique to this procedure, that is keratophakia, i.e., implantation of a lens inside the cornea, if an intraocular lens cannot be implanted in these eyes. 
     Keratophakia requires implantation of an artificial lens, either organic or synthetic, inside the cornea. The synthetic lenses are not tolerated well in this position because they interfere with the nutrition of the overlying cornea. The organic lenticulas, though better tolerated, require frozen lathe cutting of the corneal lenticule. 
     Problems with microkeratomies used for cutting lamellar cornea are irregular keratectomy or perforation of the eye. The recovery of vision is also rather prolonged. Thus, significant time is needed for the implanted corneal lenticule to clear up and the best corrective visions are thereby decreased because of the presence of two interfaces. 
     Application of ultraviolet and shorter wavelength lasers also have been used to modify the cornea. These lasers are commonly known as excimer lasers which are powerful sources of pulsed ultraviolet radiation. The active medium of these lasers are composed of the noble gases such as argon, krypton and xenon, as well as the halogen gases such as fluorine and chlorine. Under electrical discharge, these gases react to build excimer. The stimulated emission of the excimer produces photons in the ultraviolet region. 
     Previous work with this type of laser has demonstrated that far ultraviolet light of argon-fluoride laser light with the wavelength of 193 nm. can decompose organic molecules by breaking up their bonds. Because of this photoablative effect, the tissue and organic and plastic material can be cut without production of heat, which would coagulate the tissue. The early work in ophthalmology with the use of this type of laser is reported for performing radial cuts in the cornea in vitro (Trokel, Am. J. Ophthalmol 1983 and Cotliar, Ophthalmology 1985). Presently, all attempts to correct corneal curvature via lasers are being made to create radial cuts in the cornea for performance of radial keratotomy and correction of low myopia. 
     Because of the problems related to the prior art methods, there is a continuing need for improved methods to correct eyesight. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is a primary object of the present invention to provide a method for modifying corneal curvature via introducing a transparent optical material into an internal portion of the cornea. 
     Another object of the invention is to provide such a method that can modify the curvature of a live cornea, thereby eliminating the need and complications of working on a frozen cornea. 
     Another object of the invention is to provide a method for improving eyesight without the use of glasses or contact lenses, but rather by merely modifying the corneal curvature. 
     Another object of the invention is to provide a method for modifying corneal curvature by using a source of laser light in a precise manner and introducing a transparent optical material into the stroma of the cornea. 
     Another object of the invention is to provide a method that can modify the curvature of a live cornea without the need of sutures. 
     Another object of the invention is to provide a method that can modify the curvature of a live cornea with minimal incisions into the epithelium and Bowman&#39;s layer of the cornea. 
     Another object of the invention is to provide a method for modifying the corneal curvature by ablating or coagulating the corneal stroma and introducing a transparent optical material into the stroma of the cornea. 
     The foregoing objects are basically attained by a method of modifying the curvature of a patient&#39;s live cornea comprising the steps of separating an internal area of the live cornea into first and second opposed internal surfaces, the first internal surface facing in the posterior direction and the second internal surface facing in the anterior direction, introducing a transparent optical material between the surfaces, and recombining the first and second internal surfaces, the separating, directing and recombining steps taking place without freezing the cornea. other objects, advantages, and salient features of the present invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses preferred embodiments of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Referring now to the drawings which form a part of this original disclosure: 
     FIG. 1 is a side elevational view in section taken through the center of an eye showing the cornea, pupil and lens; 
     FIG. 2 is a side elevational view in section similar to that shown in FIG. 1 except that a thin layer has been removed from the front of the cornea, thereby separating the cornea into first and second opposed internal surfaces; 
     FIG. 3 is a diagrammatic side elevational view of the eye shown in FIG. 2 with a laser beam source, diaphragm and guiding mechanism being located adjacent thereto; 
     FIG. 4 is a side elevational view in section of an eye that has been treated by the apparatus shown in FIG. 3 with ablation conducted in an annular area spaced from the center of the internal surface on the cornea; 
     FIG. 5 is a front elevational view of the ablated cornea shown in FIG. 4; 
     FIG. 6 is a side elevational view in section showing the ablated cornea of FIGS. 4 and 5 with the thin layer previously removed from the cornea replaced onto the ablated area in the cornea, thereby increasing the curvature of the overall cornea; 
     FIG. 7 is a side elevational view in section of an eye which has been ablated in the central area of the internal surface on the cornea; 
     FIG. 8 is a front elevational view of the cornea having the central ablated portion shown in FIG. 7; 
     FIG. 9 is a side elevational view in section of the ablated cornea of FIGS. 7 and 8 in which the thin layer previously removed from the cornea is replaced over the ablated area, thereby reducing the curvature of the overall cornea; 
     FIG. 10 is a front elevational view of the adjustable diaphragm shown in FIG. 3 used for directing the laser beam towards the eye; 
     FIG. 11 is a front elevational view of the guiding mechanism shown in FIG. 3 having a rotatable orifice of variable size formed therein, for directing the laser beam towards the eye in a predetermined pattern; 
     FIG. 12 is a right side elevational view of the guiding mechanism shown in FIG. 11; 
     FIG. 13 is a right side elevational view in section taken along line  13 — 13  in FIG. 11 showing the internal parts of the guiding mechanism; 
     FIG. 14 is a front elevational view of a modified guiding mechanism including a movable orifice; 
     FIG. 15 is a diagrammatic side elevational view of a second modified guiding mechanism for a laser beam including a universally supported mirror and actuating motors used for moving the mirror and thereby guiding the laser beam in the predetermined pattern; 
     FIG. 16 is a diagrammatic side elevational view of a third modified guiding mechanism comprising a housing and a rotatable fiber optic cable; 
     FIG. 17 is an end elevational view of the housing and fiber optic cable shown in FIG. 16; 
     FIG. 18 is a diagrammatic side elevational view of a laser source, diaphragm and guiding mechanism for use in ablating the thin layer removed from the cornea, which is shown supported by a pair of cups; 
     FIG. 19 is a front elevational view of a live cornea which has been cut with a spatula to separate the central portion of the cornea into first and second opposed internal surfaces in accordance with the present invention; 
     FIG. 20 is a side elevational view in section taken along line  20 — 20  of the cornea shown in FIG. 19; 
     FIG. 21 is a front elevational view of a cornea that has been cut as shown in FIG. 19 with ablation conducted in the central portion of the cornea by a laser; 
     FIG. 22 is a side elevational view in section taken along line  22 — 22  of the cornea shown in FIG. 21; 
     FIG. 23 is a side elevational view in section taken through the center of an eye showing the ablated cornea of FIGS. 19-22 with the fiber optic tip removed; 
     FIG. 24 is a side elevational view in section taken through the center of an eye showing the ablated cornea of FIGS. 19-23 in its collapsed position, thereby decreasing the curvature of the central portion of the cornea; 
     FIG. 25 is an enlarged, partial cross-sectional view of a cornea with a fiber optic tip cutting, separating and ablating the cornea into first and second opposed internal surfaces; 
     FIG. 26 is an enlarged, partial cross-sectional view of a cornea with a fiber optic tip having an angled end for ablating the cornea; 
     FIG. 27 is an enlarged, partial cross-sectional view of a cornea with a fiber optic tip having a bent end for ablating the cornea; 
     FIG. 28 is a front elevational view of a live cornea in which a plurality of radially extending cuts have been made with a spatula to separate the cornea at each of the radially extending cuts into first and second opposed internal surfaces in accordance with the present invention; 
     FIG. 29 is a front elevational view of a cornea in which the radially extending cuts shown in FIG. 28 have been ablated to create a plurality of radially extending tunnels; 
     FIG. 30 is a side elevational view in section taken along line  30 — 30  of the cornea of FIG. 29 with the fiber optic tip removed; 
     FIG. 31 is a side elevational view in section taken along the center of an eye showing the ablated cornea of FIGS. 28-30 in its collapsed position, thereby decreasing the curvature of the central portion of the cornea; 
     FIG. 32 is a front elevational view of a live cornea in which a plurality of radially extending cuts have been made with a spatula to separate the cornea at each of the radially extending cuts into first and second opposed internal surfaces in accordance with the present invention; 
     FIG. 33 is a side elevational view in section taken along line  33 — 33  of the cornea of FIG. 32 with the spatula removed; 
     FIG. 34 is a front elevational view of a cornea that has been radially cut as shown in FIGS. 32 and 33 with coagulation conducted at the ends of the radial cuts by a laser, thereby increasing the curvature of the central portion of the cornea; 
     FIG. 35 is a side elevational view in section taken along line  35 — 35  of the cornea of FIG. 34 with the laser removed and coagulation conducted at the ends of the radial cuts to increase the curvature of the central portion of the cornea; 
     FIG. 36 is an enlarged, partial cross-sectional view of a cornea with a drill tip removing tissue therefrom; 
     FIG. 37 is a front elevational view of a live cornea that has been cut to form an intrastromal pocket and showing a tool for injecting or implanting ocular material into the pocket; 
     FIG. 38 is an enlarged side elevational view in section taken through the center of an eye showing the intrastromal pocket over filled with ocular material thereby increasing the curvature of the central portion of the cornea; 
     FIG. 39 is an enlarged side elevational view in section taken through the center of an eye showing the intrastromal pocket partially filled with ocular material thereby decreasing the curvature of the central portion of the cornea; 
     FIG. 40 is an enlarged side elevational view in section taken through the center of an eye showing the intrastromal pocket completely filled with ocular material restoring the curvature of the central portion of the cornea to its original curvature; 
     FIG. 41 is a rear elevational view of an ocular implant or material in accordance with the present invention for implanting into a cornea; 
     FIG. 42 is a cross-sectional view of the ocular implant or material illustrated in FIG. 41 taken along section line  42 — 42 ; 
     FIG. 43 is an enlarged side elevational view in section taken through the center of an eye showing the intrastromal pocket with the ocular implant or material of FIGS. 41 and 42 therein for increasing the curvature of the central portion of the cornea; 
     FIG. 44 is an enlarged side elevational view in section taken through the center of an eye showing the intrastromal pocket with the ocular implant or material of FIGS. 41 and 42 therein for decreasing the curvature of the central portion of the cornea; 
     FIG. 45 is an enlarged side elevational view in section taken through the center of an eye showing the intrastromal pocket with the ocular implant or material of FIGS. 41 and 42 therein for maintaining the original curvature of the central portion of the cornea; 
     FIG. 46 is a front elevational view of a live cornea which has been cut to form a plurality of radial tunnels or pockets and showing a tool for injecting or implanting ocular material into the tunnels; 
     FIG. 47 is an enlarged side elevational view in section taken through the center of the eye showing the radial tunnels or pockets of FIG. 46 overfilled with ocular material thereby modifying the cornea and increasing its curvature; 
     FIG. 48 is an enlarged side elevational view in section taken through the center of the eye showing the radial tunnels or pockets of FIG. 46 underfilled with ocular material thereby modifying the cornea and decreasing its curvature; 
     FIG. 49 is an enlarged side elevational view in section taken through the center of the eye showing the radial tunnels or pockets of FIG. 46 completely filled with ocular material thereby modifying the cornea; 
     FIG. 50 is an enlarged side elevational view in section taken through the center of the eye showing one of the tunnels or pockets overfilled with ocular material to increase the curvature of a selected portion of the cornea and another tunnel or pocket underfilled to decrease the curvature of a selected portion of the cornea; 
     FIG. 51 is an enlarged side elevational view in section taken through the center of the eye showing one of the tunnels or pockets completely filled with ocular material to maintain a portion of the cornea at its original shape and another tunnel or pocket overfilled with ocular material to increase the curvature of a selected portion of the cornea; 
     FIG. 52 is an enlarged side elevational view in section taken through the center of the eye showing one of the tunnels or pockets completely filled with ocular material to maintain a portion of the cornea at its original shape and another tunnel or pocket unfilled to collapse or decrease the curvature of a selected portion of the cornea; 
     FIG. 53 is an enlarged side elevational view in section taken through the center of the eye showing one of the tunnels or pockets overfilled with ocular material to increase the curvature of a selected portion of the cornea and another tunnel or pocket unfilled to collapse or decrease the curvature of a selected portion of the cornea; 
     FIG. 54 is an exploded side elevational view in section taken through the center of an eye showing a thin layer or portion of the cornea completely removed from the live cornea and the ocular material or implant of FIGS. 41 and 42 positioned between the thin layer and the remainder of the live cornea; 
     FIG. 55 is an enlarged side elevational view in section taken through the center of the eye showing the ocular implant illustrated in FIGS. 41 and 42 implanted in the cornea with the thin layer of the cornea replaced over the ocular implant to increase the curvature of the cornea; 
     FIG. 56 is an enlarged side elevational view in section taken through the center of the eye showing the ocular implant illustrated in FIGS. 41 and 42 implanted in the cornea with the thin layer of the cornea replaced over the ocular implant to decrease the curvature of the cornea; 
     FIG. 57 is an enlarged side elevational view in section taken through the center of the eye showing the ocular implant illustrated in FIGS. 41 and 42 implanted in the cornea with the thin layer of the cornea replaced over the ocular implant to maintain the cornea&#39;s original curvature; 
     FIG. 58 is an enlarged side elevational view in cross section through the center of an eye showing a circular cut or groove in the cornea and the ocular implant of FIGS. 41 and 42 positioned between the separated internal layers, but before the separated internal layers are replaced or rejoined on the cornea; 
     FIG. 59 is a side elevational view in section through the center of the eye showing the outer surface of the cornea cut to form a flap having a portion still attached to the cornea to expose the intrastromal layers of the cornea; 
     FIG. 60 is a front elevational view of an ocular implant or material in accordance with the present invention for implanting within the intrastromal area of the cornea; and 
     FIG. 61 is a cross-sectional view of the ocular implant or material illustrated in FIG. 60 taken along section line  61 — 61 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As seen in FIG. 1, an eye  10  is shown comprising a cornea  12 , a pupil  14 , and a lens  16 . If the combination of the cornea and lens does not provide adequate vision, the cornea can be modified in accordance with the invention to modify the refractive power of the combined corneal and lens system, to thereby correct vision. This is accomplished first by removing a thin layer  18  from the center part of a patient&#39;s live cornea  12  by cutting via a means for removing  19 , such as a scalpel, via cutting, this thin layer being on the order of about 0.2 mm in thickness with the overall cornea being about 0.5 mm in thickness. Once the thin layer  18  is cut and removed from the cornea, it exposes first and second opposed internal surfaces  20  and  21  resulting from the surgical procedure. Advantageously, it is the exposed internal surface  20  on the remaining part of the cornea that is the target of the ablation via the excimer laser. On the other hand, the cut internal surface  21  on the removed thin layer of the cornea can also be the target of the laser, as illustrated in FIG.  18  and discussed in further detail hereinafter. 
     As seen in FIG. 3, the apparatus used in accordance with the invention comprises a source of a laser beam  22 , an adjustable diaphragm  24 , and a guiding mechanism  26 , all aligned adjacent the eye  10  and supported on a suitable base  28 . 
     The laser beam source  22  is advantageously an excimer laser of the argon-fluoride or krypton-fluoride type. This type of laser will photoablate the tissue of the cornea, i.e., decompose it without burning or coagulating which would unduly damage the live tissue. This ablation removes desired portions of the cornea and thereby allows for modification of the curvature thereof. 
     The adjustable diaphragm  24  seen in FIGS. 3 and 10 is essentially a conventional optical diaphragm with an adjustable central orifice  30  that can be increased or decreased in radial size by a manipulation of a lever  32  coupled to the diaphragm. The diaphragm is advantageously supported in a ring  34  that is in turn supported on a stand  36  on base  28 . The material forming the diaphragm is opaque to laser light and thus when the laser is directed towards the diaphragm, it will pass therethrough only via the orifice  30 . The diaphragm  24  can be used in conjunction with the guiding mechanism  26 , to be described in more detail hereinafter, to restrict the size of the laser beam passing to the guiding mechanism  26 , or it can be used by itself to provide ablation of the exposed internal surface  20  of a cornea at its center. 
     This is illustrated in FIGS. 7-9 where a substantially disc-shaped ablated portion  38  is formed in the central exposed internal surface  20  by directing the laser beam  22  through orifice  30  of the diaphragm  24 . By modifying the size of the orifice, the disc-shaped ablated portion  38  can be varied in size. Also, by varying the size of the orifice over time, either a concave or convex ablated portion can be formed, as desired. As shown in FIG. 9, once the ablated portion  38  is as desired, the previously removed thin layer  18  is replaced onto the cornea in the ablated portion  38  and can be connected thereto via sutures  40 . 
     Because the ablated portion  38  as seen in FIG. 7 is essentially a uniform cylindrical depression in the exposed internal surface  20 , when the thin corneal layer  18  is replaced, the curvature of the cornea is decreased, thereby modifying the refractive power of the cornea and lens system. 
     As seen in FIG. 10, lever  32  is used to vary the size of orifice  30 , and is capable of being manipulated by hand or by a suitable conventional motor, which can be coordinated to provide an expansion or contraction of the orifice as necessary over time. 
     As seen in FIGS. 3,  11 ,  12  and  13 , the guiding mechanism  26  can be utilized in addition to or in place of the diaphragm  24  to guide the laser light onto the cornea. This guiding mechanism  26  is especially advantageous for forming an annular ablated portion  42  in surface  20  as seen in FIGS. 4-6 for increasing the overall curvature of the cornea. 
     As seen in FIGS. 4 and 5, this annular ablated portion  42  is spaced from the center of the exposed internal surface  20  and when the previously removed thin corneal layer  18  is replaced and sutured, the thin layer tends to be more convex, thereby modifying the overall curvature of the cornea. 
     As seen in FIGS. 11-13, the guiding mechanism  26  comprises a stand  44  supporting a ring  46 , this ring having a radially inwardly facing recess  48  therein. A disc  50 , which is opaque to laser light, is located inside the ring and has a cylindrical extension  52  with an outwardly facing flange  54  rotatably and slidably received in the recess. On the cylindrical extension  52  which extends past ring  46  is an exterior toothed gear  56  that is in engagement with a pinion  58  supported on a shaft  60  of a motor  62 . Rotation of pinion  58  in turn rotates gear  56  and disc  50 . 
     The disc  50  itself has an elongated rectangular orifice  64  formed therein essentially from one radial edge and extending radially inwardly past the center point of the disc. Adjacent the top and bottom of the orifice  64  are a pair of parallel rails  66  and  68  on which a masking cover  70 , which is U-shaped in cross section, is slidably positioned. Thus, by moving the masking cover  70  along the rails, more or less of the orifice  64  is exposed to thereby allow more or less laser light to pass therethrough and onto the cornea. Clearly, the larger the orifice, the larger the width of the annular ablated portion  42  will be. By rotating the disc, the orifice  64  also rotates and thus the annular ablated portion  42  is formed. 
     Embodiment of FIG. 14 
     Referring now to FIG. 14, a modified guiding mechanism  72  is shown which is similar to guiding mechanism  26  shown in FIGS. 11-13 except that the size of the orifice is not variable. Thus, the modified guiding mechanism  72  is comprised of a ring  74  on a stand  76 , an opaque disc  78  which is rotatable in the ring via a suitable motor, not shown, and a slidable masking cover  80 . Disc  78  has a rectangular orifice  82  extending diametrically there across with parallel rails  84  and  86  on top and bottom for slidably receiving the masking cover  80  thereon, this cover being U-shaped for engagement with the rails. The masking cover  80  has its own orifice  88  therein which aligns with orifice  82  on the disc. Thus, by sliding the masking cover  80  along the rails of the disc, the location of the intersection of orifice  88  and orifice  82  can be varied to vary the radial position of the overall through orifice formed by the combination of these two orifices. As in guiding mechanism  26 , the masking cover  80  and disc  78  are otherwise opaque to laser light except for the orifices. 
     Embodiment of FIG. 15 
     Referring now to FIG. 15, a second modified guiding mechanism  90  is shown for directing laser light from laser beam source  22  to the cornea  12  along the desired predetermined pattern. This guiding mechanism  90  comprises a mirror  92  universally supported on a stand  94  via, for example, a ball  96  and socket  98  joint. This mirror  92  can be pivoted relative to the stand through the universal joint by means of any suitable devices, such as two small piezoelectric motors which engage the mirror at 90° intervals. For example, such a piezoelectric motor  100  having a plunger  102  coupled thereto and engaging the rear of the mirror can be utilized with a spring  104  surrounding the plunger and maintaining the mirror in a null position. The motor  100  is rigidly coupled to a base  106  via a stand  108 . The second piezoelectric motor, not shown, can be located so that its plunger engages the rear of the mirror 90° from the location of motor  100 . By using these two motors, springs and plungers, the mirror  92  can be fully rotated in its universal joint to direct the laser beam from source  22  onto the cornea  12  to ablate the cornea in a predetermined pattern. 
     Embodiment of FIGS. 16-17 
     Referring now to FIGS. 16 and 17, a third modified guiding mechanism  111  is shown for ablating a cornea  12  via directing laser light from laser source  22 . This modified guiding mechanism  111  basically comprises a cylindrical housing  113  having an opaque first end  115  rotatably receiving the end of a fiber optic cable  117  therein. The second end  119  of the housing comprises a rotatable opaque disc having a flange  121  engaging the housing and an external gear  123  which in turn engages pinion  125 , which is driven via shaft  127  and motor  129 . Thus, rotation of the pinion results in rotation of gear  123  and thus the opaque second end  119  of the housing. This second end  119  has a diametrically oriented rectangular orifice  131  therein which receives the other end of the fiber optic cable  117  therein. That end of the fiber optic cable is either dimensioned so that it fits fairly tightly into the orifice or there is an additional suitable assembly utilized for maintaining the fiber optic cable end in a predetermined position in the orifice during rotation of the second end. However, this end would be movable radially of the orifice to change the position of the annular ablated portion formed by utilizing this guiding mechanism. 
     Embodiment of FIG. 18 
     Referring now to FIG. 18, rather than ablating the exposed internal surface  20  on the cornea  12 , the inner surface  133  of the removed thin corneal layer  18  can be ablated utilizing the apparatus shown in FIG.  18 . Likewise, the apparatus of FIG. 18 can be used on an eye bank cornea removed from the eye and then positioned in the patient&#39;s eye to modify the curvature of the patient&#39;s combined corneal structure. This apparatus as before includes the source of the laser light  22 , an adjustable diaphragm  24 , and a guiding mechanism  26 . In addition, an assembly  134  is utilized to support the rather flimsy removed thin corneal layer. This assembly  134  comprises a pair of laser light transparent cups  136  and  138  that are joined together in a sealing relationship via clamps  140  and engage therebetween the outer periphery of the thin corneal layer  18 . Each of the cups has an inlet pipe  142 ,  144  for injecting pressurized air or suitable fluid into each via pumps  146  and  148 . By using this pressurized container, the thin corneal layer  18  is maintained in the desired curvature so that the laser beam can provide a precise ablated predetermined pattern therein. In order to maintain the curvature shown in FIG. 18, the pressure on the right hand side of the thin layer is slightly greater than that on the left hand side. 
     Once the thin corneal layer  18  is suitably ablated as desired, it is replaced on the exposed internal surface  20  of the cornea and varies the curvature of the overall cornea as described above and illustrated in FIGS. 4-9. 
     Embodiment of FIGS. 19-27 
     Referring now to FIGS. 19-27, a patient&#39;s live in situ eye  110  is shown for the treatment of myopia in accordance with the present invention. Eye  110  includes a cornea  112 , a pupil  114 , and a lens  116 , and is treated in accordance with the present invention without freezing the cornea. 
     Correction of myopia can be achieved by decreasing the curvature of the outer surface of cornea  112  (i.e., flattening the central portion of the cornea). This is accomplished by first cutting an incision  118  into the epithelium of cornea  112 . Incision  118  may be curved or straight, and is preferably about 2.0-3.0 mm long and about 3.0-6.0 mm away from the center of cornea  112 . A laser or spatula (i.e., a double-edge knife) may be used to make incision  118  in cornea  112 . 
     As seen in FIGS. 19 and 20, once incision  118  is made, a spatula  120  is inserted into incision  118  to separate an internal area of live cornea  112  into first and second opposed internal surfaces  122  and  124 , thereby creating an intrastromal or internal pocket  126 . First internal surface  122  faces in the posterior direction of eye  110 , while second internal surface  124  faces in the anterior direction of eye  110 , and both of these surfaces extend radially relative to the center of the cornea. 
     As seen in FIGS. 19 and 20, pocket  126  is created by moving spatula  120  back and forth within an intrastromal area of cornea  112 . It is important when creating pocket  126  to keep spatula  120  in substantially a single plane and substantially tangential to the cornea&#39;s internal surfaces to prevent intersecting and rupturing the descemet or Bowman&#39;s membrane. 
     Preferably, spatula  120  is about 3.0-12.0 mm long with a thickness of about 0.1-1.0 mm, and a width of about 0.1-1.2 mm. Spatula  120  may be slightly curved, as seen in FIG. 20, or may be straight. 
     While a spatula  120  is shown in FIGS. 19 and 20 for separating the internal surfaces of cornea  112 , a fiber optic cable coupled to a laser beam source may be used instead of spatula  120  to separate cornea  112  into first and second opposed internal surfaces  122  and  124 . 
     As seen in FIGS. 21 and 22, after pocket  126  is formed, a fiber optic cable tip  130  coupled to a fiber optic cable  132 , which is in turn coupled to a laser, is then inserted through incision  118  and into pocket  126  for ablating a substantially circular area of cornea  112 , thereby removing a substantially disc-shaped portion of cornea  112  to form a disc-shaped cavity  126 ′. The laser beam emitted from tip  130  may be directed upon either first internal surface  122 , second internal surface  124 , or both, and removes three-dimensional portions therefrom via ablation. The fiber optic cable can be solid or hollow as desired. 
     The laser source for fiber optic cable  132  is advantageously a long wavelength, infrared laser, such as a CO 2 , an erbium or holmium laser, or a short wavelength, UV-excimer laser of the argon-fluoride or krypton-fluoride type. This type of laser will photoablate the intrastromal tissue of the cornea, i.e., decompose it without burning or coagulating. 
     FIGS. 25-27 illustrate three different configurations of the tip of a fiber optic cable for ablating the cornea. In FIG. 25, tip  130  has a substantially straight end for directing the laser beam parallel to the tip. As seen in FIG. 26, tip  130 ′ has an end with an angled surface for directing the laser beam at an acute angle of preferably 450 relative to the tip to aid in ablating the cornea as desired. In FIG. 27, tip  130 ″ has a curved end for bending the laser beam to aid ablating the cornea as desired. 
     As seen in FIG. 23, cornea  112  is shown with the substantially disc-shaped cavity  126 ′ formed at the center of cornea  112  just after tip  130  has been removed and prior to cornea  112  collapsing or flattening. The disc-shaped cavity  126 ′ can be varied in size and shape, depending upon the amount of curvature modification needed to correct the patient&#39;s eyesight. Accordingly, any three-dimensional intrastromal area of the cornea may be removed to modify the cornea as desired. The intrastromal area removed can be uniform or non-uniform. For example, more material can be removed from the periphery of the cornea than from the center portion. Alternatively, more material can be removed from the center portion than from the peripheral area. The removal of peripheral portions of the cornea result in an increase of the curvature of the center portion of the cornea after the collapse of the peripheral area. 
     As seen in FIG. 24, after pocket  126  is ablated and tip  130  removed, the ablated cavity  126 ′ then collapses under normal eye pressure to recombine ablated first and second internal surfaces  122  and  124  together. This collapsing and recombining of the intrastromal area of the cornea decreases the curvature of the central portion of cornea  112  from its original shape shown in broken lines to its new shape as seen in FIG.  24 . After a period of time, depending on the patient&#39;s healing abilities, the ablated surfaces heal and grow back together, resulting in a permanent modification of the corneals curvature. 
     Embodiment of FIGS. 28-31 
     Referring now to FIGS. 28-31, an eye  210  is shown for the treatment of myopia in accordance with another embodiment of the present invention, and includes a cornea  212 , a pupil  214 , and a lens  216 , the cornea being treated without freezing it. In this embodiment, correction of myopia is accomplished by first making a plurality of radially directed intrastromal incisions  218  with a flat pin or blade spatula  220 . These incisions  218  separate the cornea  218  into first and second opposed internal surfaces  222  and  224  at each of the incisions  218 . First internal surfaces  222  face in the posterior direction of eye  210 , while second internal surfaces  224  face in the anterior direction of eye  210 , and both extend radially relative to the center of the cornea. Spatula  220  may have a straight or curved blade with a maximum diameter of about 0.1-0.2 mm. A laser may be used instead of spatula  220  to make incisions  218 , if desired. 
     Incisions or unablated tunnels  218  extend generally radially towards the center of cornea  212  from its periphery. Preferably, incisions  218  stop about 3.0 mm from the center of cornea  212 , although incisions  218  may extend to the center of cornea  212 , depending upon the degree of myopia. Incisions  218  will normally extend about 3.0-10.0 mm in length, again depending on the amount of change desired in curvature of cornea  112 . While only radial incisions have been shown, it will be apparent to those skilled in the art that the incisions may be non-radial, curved, or other shapes. When creating incisions  218 , it is important to keep the spatula  220  in substantially a single plane so as not to intersect and puncture the descemet or Bowman&#39;s membrane. 
     Once intrastrcmal incisions  218  have been created with spatula  220 , a fiber optic cable tip  230  coupled to a fiber optic cable  232  and a laser is then inserted into each of the incisions  218  for ablating tunnels  226  to the desired size. The laser beam emitted from tip  230  may be directed upon either first internal surface  222 , second internal surface  224 , or both for ablating tunnels  226  and removing three-dimensional portions from these surfaces. 
     The laser source for cable  232  is advantageously similar to the laser source for cable  132  discussed above. 
     Referring now to FIGS. 30 and 31, a pair of ablated tunnels  226  are shown. In FIG. 30, cornea  212  is shown with ablated tunnels  226  just after tip  230  has been removed and prior to tunnels  226  collapsing or flattening. In FIG. 31, cornea  212  is shown after ablated tunnels  226  have collapsed to recombine first and second internal surfaces  222  and  224 , thereby flattening cornea  212 . In other words, this collapsing and recombining of the intrastromal area of the cornea decreases the curvature of the central portion of cornea  212  from its original shape shown in broken lines to its new shape as seen in FIG.  31 . By collapsing intrastromal tunnels, this allows the outer surface of the cornea to relax, i.e., decrease surface tension, thereby permitting flattening of the cornea. 
     Embodiment of FIGS. 32-35 
     Referring now to FIGS. 32-35, an eye  310  is shown for the treatment of hyperopia in accordance with another embodiment of the present invention. Eye  310  includes a cornea  312 , a pupil  314 , and a lens  316 . Correction of hyperopia can be achieved by increasing the curvature of the outer surface of cornea  312  (i.e., making the central portion of the cornea more curved), without freezing the cornea. 
     This is accomplished by making a plurality of intrastromal incisions or tunnels  318  with a spatula  320  to form first and second opposed internal surfaces  322  and  324 . Tunnels  318  extend substantially radially towards the center of cornea  312 . While eight equally spaced, radial tunnels  318  are shown, it will be apparent to those skilled in the art that more or fewer tunnels with varying distances apart may be made, depending upon the amount of curvature modification needed. 
     The initial step of making incisions or tunnels  318  of FIGS. 32-35 is similar to the initial step of making incisions  218  of FIGS. 28-31. Accordingly, spatula  320  is similar to spatula  220  discussed above. Likewise, a laser may be used to make incisions or tunnels  318  instead of spatula  320 . 
     Once tunnels  318  are created, a fiber optic cable tip  330  extending from fiber optic cable  332  is inserted into each tunnel  318  to direct a laser beam on either first internal surface  322 , second internal surface  324 , or both internal surfaces to coagulate an intrastromal portion of cornea  312 . As seen in FIG. 34, a point  326  at the end of each of the tunnels  318  is coagulated. Preferably, coagulation points  326  lie substantially on the circumference of a circle concentric with the center of cornea  312 . The size of the circle forming coagulation points  326  depends upon the amount of curvature modification needed. Likewise, the number of coagulation points and their positions in the cornea depend upon the desired curvature modification needed. 
     Coagulating intrastromal points of the cornea  312 , such as coagulation points  326 , with a laser causes those points of the cornea, and especially the collagen therein, to heat up and shrink. This localized shrinkage of the intrastromal portion of the cornea causes the outer surface of the cornea to be tightened or pulled in a posterior direction at each of the coagulation points, and thereby causes an increase in the overall curvature of the cornea as seen in FIG.  35 . Coagulation, rather than ablation, is accomplished by using a laser having a wavelength which essentially cooks the corneal tissue and which is between the wavelengths associated with long infrared light and short ultraviolet light. 
     Embodiment of FIG. 36 
     As seen in FIG. 36, rather than using a laser to remove corneal tissue in the cavities  126  formed in the cornea  112  or to form those cavities, a rotating drill tip  400  suitably coupled to a rotary or oscillating power source can be used to ablate the tissue by cutting. Likewise, any other suitable mechanical device can be used to remove the corneal tissue or form the cavities. A suitable evacuation device, such as a vacuum tube, can also be used to aid in evacuating from the cavity the tissue removed from the cornea. 
     Embodiment of FIGS. 37-45 
     Referring now to FIGS. 37-45, a patient&#39;s live in situ eye  410  is shown for the treatment of hyperopia or myopia and/or improving a patient&#39;s vision by removing opaque portions of the cornea in accordance with the present invention. The eye  410  of FIGS. 37-40 and  43 - 45  includes a cornea  412 , a pupil  414  and a lens  416 , and is treated in accordance with the present invention without freezing any portion of cornea  412 . 
     Correction of myopia and hyperopia can be achieved by modifying the curvature of the outer surface of cornea  412 , i.e., flattening the central portion of a cornea in the case of myopia or increasing the curvature in the case of hyperopia. This is accomplished by first cutting an incision  418  into the epithelium of cornea  412  as seen in FIG.  37 . Incision  418  may be curved or straight, and is preferably about 2.0-3.0 mm long and about 3.0-6.0 mm away from the center of cornea  412 . A laser or a doubleedge knife may be used to make incision  418  in cornea  412 . 
     As seen in FIGS. 37-40 and  43 - 45 , once incision  418  is made, a spatula or laser probe is inserted into incision  418  to separate an internal area of live cornea  412  into first and second opposed internal surfaces  422  and  424 , thereby creating an intrastromal or internal pocket  426  as in the previous embodiment of FIGS. 19-27. First internal surface  422  faces in the posterior direction of eye  410 , while second internal surface  424  faces in the anterior direction of eye  410 , and both of these surfaces extend radially relative to the center of the cornea  412 . 
     Pocket  426  can have corneal tissue removed from either or both of internal surfaces  422  and  424 . In other words, internal surfaces  422  and  424  of intrastromal pocket  426  can be ablated or cut to define a cavity. The ablating or removing of the internal surfaces  422  and  424  of cornea  412  is particularly desirable to remove opaque areas of cornea  412 . Alternatively, the internal surfaces  422  and  424  of cornea  412  can be removed by a scalpel or a diamond tipped drill similar to the embodiments discussed above. Pocket  426  can be created by substantially the same method as previously discussed. of course, incision  418  and pocket  426  can be made in one single step by a laser or a cutting mechanism. Alternatively, none of the corneal tissue can be removed from internal surfaces  422  and  424 . 
     As shown in FIGS. 37-40 and  43 - 45 , once the pocket  426  is formed, an ocular material  428  or  430  is inserted into pocket  426  by a tool  450 . Ocular material  428  or  430  as used herein refers to transparent fluids or solids or any combination thereof. In the examples of FIGS. 38-40, the ocular material is a gel or fluid type material  428 , which can be injected into pocket  426  via tool  450 . In other words, in the examples of FIGS. 38-40, tool  450  is a needle for injecting ocular material  428  into pocket  426 . In examples of FIGS. 43-45, the ocular material is a flexible, resilient ring shaped member  430 . 
     In either case, ocular material  428  or  430  can have either the same refractive index as the intrastromal tissue of cornea  412  or a different refractive index from the intrastromal tissue of cornea  412 . Thus, the vision of the patient can be modified by curvature modification and/or by changing the refractive index. Moreover, the patient&#39;s vision can be modified by merely removing opaque portions of the cornea and replacing them with ocular material with a refractive index the same as the intrastromal tissue of cornea  412 . 
     In the examples of FIGS. 38-40 using ocular material  428 , pocket  426  can be overfilled, partially filled, or completely filled to modify the cornea as needed. The cavity of pocket  426  can be filled completely with the ocular material to restore the normal curvature of cornea  426  as seen in FIG.  40 . The amount of ocular material introduced to pocket  426  can be increased to increase the curvature of the cornea from the original curvature to treat hyperopia as seen in FIG.  38 . Alternatively, the amount of the ocular material introduced to pocket  426  can be reduced to decrease the curvature or flatten cornea  412  from the original curvature to treat myopia as seen in FIG.  39 . This method is suitable for correctly vision of  12  diopters or more. After the pocket  426  is filled, the internal surfaces  422  and  424  of pocket  426  come together to encapsulate ocular material  428  within cornea  412 . The surfaces heal and grow back together, resulting in a permanent modification of the corneals curvature. 
     The ocular material  428  injected into pocket  426  can be any suitable material that is bio-compatible and does not visually interfere with the patient&#39;s eyesight. Preferably, the ocular material  428  of FIGS. 38-40 is a transparent gellable collagen such as gelatin in an injectable form which is available from various commercial sources as known in the art. Generally, the collagen to be used in the present invention is a type I collagen. Of course, ocular material  428  can be a transparent or translucent bio-compatible polymer gel such as a silicone gel or an injectable polymethylmethacrylate. Preferably, ocular material  428  is a polymeric material that is transparent, flexible, and hydrophilic. It will be understood by those skilled in the art from this disclosure that ocular material  428  can be any suitable polymeric material. Of course, ocular material  428  can be a flexible solid or semi-solid material as shown in the examples of FIGS. 41-45 discussed below regarding ocular material  430  which can be made from collagen or synthetic polymers such as acrylic polymers, silicones and polymethylmethacrylates. 
     Referring now to the examples of FIGS. 43-45 using a solid or semi-solid ocular material or implant  430 , tool  450  is utilized to insert ocular material or implant  430  through the small opening formed by incision  418  in the external surface of cornea  412 , as seen in FIG. 37 so that ocular material or implant  430  can be implanted into pocket  426  and centered about the main optical axis of eye  410 . Ocular material or implant  430  is preferably a resilient, flexible member, which can be folded for insertion into pocket  426  through the small opening formed by incision  418 . 
     The ocular implant  430  is made from a bio-compatible transparent material. Preferably, ocular implant  430  is made from any suitable transparent polymeric material. Suitable materials include, for example, collagen, silicone, polymethylmethacrylate, acrylic polymers, copolymers of methyl methacrylate with siloxanylalkyl methylacrylates, cellulose acetate butyrate and the like. Such materials are commercially available from contact lens manufacturers. For example, optical grade silicones are available from Allergan, Alcon, Staar, Chiron and bolab. Optical grade acrylics are available from Allergan and Alcon. A hydrogel lens material consisting of a hydrogel optic and polymethylmethacrylate is available from Staar. 
     Similar to the fluid type ocular material  428 , discussed above, solid or semi-solid ocular material or implant  430  can overfill, partial fill or completely fill pocket  426  to modify cornea  412  as needed. While ablation or removal of intrastromal tissue of pocket  426  is required for decreasing the curvature of cornea  412  as seen in FIG. 44, or for maintaining the original curvature of cornea  412  as seen in FIG. 45, such ablation or removal of intrastromal tissue of pocket  426  is not necessary for increasing the curvature of cornea  412 . In any event, the amount of intrastromal tissue to be removed, if any, from pocket  426  depends on the shape of ocular material  430  and the desired resultant shape of cornea  412 . 
     As seen in FIGS. 41 and 42, ocular material or implant  430  has a substantially annular ring shape with a center opening or circular hole  432 . Center opening  432  allows intrastromal fluids to pass through ocular material or implant  430 . Preferably, ocular material  430  has a circular periphery with an outer diameter in the range of about 3.0 mm to about 9.0 mm. Center opening  432  preferably ranges from about 1.0 mm to about 8.0 mm. The thickness of ocular material  430  is preferably about 20 microns to about 1000 microns. 
     In the embodiment of FIGS. 41-45, ocular material or implant  430  has a planar face  434  and a curved face  436 . Planar face  434  forms a frustoconically shaped surface, which faces inwardly towards the center of eye  410  in a posterior direction of eye to contact internal surface  424  of pocket  426 . Curved face  436  can be shaped to form a corrective lens or shaped to modify the curvature cornea  412  as seen in FIGS. 43 and 44. Of course, ocular material  430  can be shaped to replace opaque areas of cornea  412 , which have been previously removed, and/or to form a corrective lens without changing the curvature of cornea  412  as seen in FIG.  45 . 
     When center opening  432  is about 2.0 mm or smaller, center opening  432  acts as a pin hole such that the light passing through is always properly focused. Accordingly, ocular material  430  with such a small center opening  432  can be a corrective lens, which is not severely affected by center opening  432 . However, when ocular material  430  has its center opening  432  greater than about 2.0 mm, then ocular material  430  most likely will have the same refractive index as the intrastromal tissue of cornea  412  for modifying the shape of cornea  412  and/or replacing opaque areas of the intrastromal tissue of cornea  412 . Of course, all or portions of ocular material  430  can have a refractive index different from the intrastromal tissue of cornea  412  to correct astigmatisms or the like, when center opening  432  is greater than about 2.0 mm. 
     The amount of curvature modification and/or the corrective power produced by ocular material  430  can be varied by changing the thickness, the shape, the outer diameter and/or the size of the center opening  432 . Moreover, instead of using a continuous, uniform ring as illustrated in FIGS. 41 and 42, ocular material  430  can be a ring with non-uniform cross-section in selected areas as necessary to correct the patient&#39;s vision. In addition, ocular material  430  could be replaced with a plurality of separate solid or semi-solid ocular implants at selected locations within pocket  426  of cornea  412 . 
     Embodiment of FIGS. 46-53 
     Referring now to FIGS. 46-53, an eye  510  is shown for the treatment of hyperopia or myopia and/or improving vision by removing opaque portions of the cornea, in accordance with another embodiment of the present invention. Eye  510  includes a cornea  512 , a pupil  514 , and a lens  516 . As in the previous embodiments, cornea  512  is treated without freezing it. 
     In this embodiment, correction of hyperopia or myopia or removal of opaque portions can be accomplished by first making a plurality of radially directed intrastromal incisions  518  with a flat pin, laser or blade spatula similar to the procedure mentioned above discussing the embodiment of FIGS. 28-31. These incisions  518  separate cornea  512  into first and second opposed internal surfaces  522  and  524 , respectively, at each of the incisions  518 . First internal surfaces  522  face in the posterior direction of eye  510 , while second internal surfaces  524  face in the anterior direction of eye  510 , and both extend radially relative to the center of cornea  512 . 
     Incisions or unablated tunnels  518  extend generally radially towards the center of cornea  512  from its periphery. Preferably, incisions  518  stop about 3.0 mm from the center of cornea  512 , although incisions  518  may extend to the center of cornea  512 , depending upon the degree of hyperopia or myopia. Incisions  518  will normally extend about 3.0-10.0 mm in length, again depending on the amount of change desired in curvature of cornea  512 . While only radial incisions have been shown, it will be apparent to those skilled in the art that the incisions may be non-radial, curved, or other shapes. When creating incisions  518 , it is important to keep the spatula or laser in substantially a single plane so as not to intersect and puncture the descemet or Bowman&#39;s membrane. 
     Once intrastromal incisions  518  have been created, a fiber optic cable tip coupled to a fiber optic cable and a laser can be optionally inserted into each of the incisions  518  for ablating tunnels  526  to the desired size, if needed or desired. The laser beam emitted from the tip may be directed upon either first internal surface  522 , second internal surface  524 , or both for ablating tunnels  526  to sequentially and incrementally remove three-dimensional portions from these surfaces. The laser source for the cable is advantageously similar to the laser source for the cable as discussed above. Alternatively, a drill or other suitable micro-cutting instruments can be used to sequentially and incrementally remove portions of the cornea. 
     Referring to FIG. 46, a plurality of radial tunnels  526  are shown with a suitable tool  550  projecting into one of the tunnels  526  for introducing optical material  528  into tunnels  526  to modify cornea  512 . Ocular material  528  as used herein refers to transparent fluids or solids or any combination thereof. In the examples of FIGS. 47-53, ocular material  528  is a gel or fluid type material, which can be injected into pockets  526  via tool  550 . Preferably, in this case, tool  550  is a needle for injecting ocular material  528  into pockets  526 . Of course as in the preceding embodiment, a solid implant or ocular material may be introduced into pockets  526 . Also, ocular material  528  can have either a refractive index, which is different or the same as the intrastromal tissue of cornea  512  as needed and/or desired, whether the ocular material is a gel, a solid or any combination thereof. 
     As shown in FIG. 47, optical material  528  injected into the ablated tunnels  526  expands the outer surface of cornea  512  outward to change or modify the curvature of the central portion of cornea  512  from its original shape shown in broken lines to its new shape shown in full lines. 
     As seen in FIGS. 47-53, the various radial tunnels  526  can be filled with ocular material  528  to overfill pockets  526  (FIG.  47 ), underfill pockets  526  (FIG. 48) or completely fill pockets  526  (FIG.  49 ). Thus, by introducing various amounts of optical material into pockets  526 , the curvature of cornea  512  can be varied at different areas. Similarly, selected tunnels  526  can be overfilled or completely filled at selected areas, while other selected tunnels can be partially filled, completely filled or unfilled to collapse or decrease the curvature of cornea  512  at other selected areas as shown in FIGS. 50-53. The selective alteration of the curvature in different areas of the cornea are particularly desirable in correcting astigmatisms. 
     In the embodiment illustrated in FIGS. 47-53, the intrastromal areas of tunnels  526  are preferably ablated by a laser or cut by a micro-cutting instrument for sequentially and incrementally removing three-dimensional portions of cornea  512  to form tubular pockets from tunnels  526 . However, as in the previous embodiment of FIGS. 37 and 38, the incisions  518  can be filled with ocular material without previously ablating or cutting the internal surfaces  522  and  524  of cornea  512  to expand the cornea  512  for increasing its curvature. Ablating the internal surfaces of the cornea is advantageous to remove opaque areas of the cornea which can then be filled with the ocular material. 
     As shown in FIGS. 48 and 50, the amount of ocular material  528  introduced into the ablated areas of pockets  526  can be less then the amount of ablated material to reduce the curvature of cornea  512 . Alternatively, the amount of ocular material  528  introduced into the ablated areas of pockets  526  can completely fill pockets  526  to retain the original curvature of cornea  512  as seen in FIGS. 49,  51  and  52 . 
     Embodiment of FIGS. 54-57 
     Referring now to FIGS. 54-57, an eye  610  is shown for treatment of hyperopia, myopia and/or removal of opaque portions in accordance with another embodiment of the invention using an implant or ocular material  630 . As shown, the eye  610  includes a cornea  612 , a pupil  614  and a lens  616 . As in the previous embodiments, the live eye  610  is treated without freezing cornea  612  or any part thereof. 
     In this embodiment, a thin layer  618  of cornea  612  is first removed from the center portion of a patient&#39;s live cornea  612  by cutting using a scalpel or laser. The thin layer  618  is typically on the order of about 0.2 mm in thickness with overall cornea being on the order of about 0.5 mm in thickness. Once the thin layer  618  is removed from cornea  612 , it exposes first and second opposed internal surfaces  622  and  624 . Generally, either or both of the internal surfaces  622  and/or  624  are the target of the ablation by the excimer laser. Alternatively, tissue from the internal surfaces  622  and/or  624  can be removed by a mechanical cutting mechanism, or substantially no tissue is removed from the cornea. 
     As illustrated in FIG. 54, a disc-shaped portion  626  is removed from internal surface  624  by a laser beam or other cutting mechanism. In this embodiment, internal surface  624  is shaped to include a concave annular portion  627 . The method and laser apparatus as described above in the embodiment of FIGS. 1-10 can be used for removing tissue from cornea  612  in substantially the same manner. 
     After the exposed internal surface  622  or  624  of cornea  612  is ablated, if necessary, an annular ring shaped implant or ocular material  630  is placed on ablated portion  628  of cornea  612 . The previously removed thin layer  618  of cornea  612  is then replaced onto ablated portion  626  of cornea  612  to overlie implant or ocular material  630  and then reconnected thereto. The resulting cornea can have a modified curvature thereby modifying the refractive power of the cornea and lens system as seen in FIGS. 55 and 56, or the original curvature with opaque areas removed and/or modified refractive power as seen in FIG.  57 . 
     The ocular implant or material  630  in the embodiment shown in FIGS. 54-57 has a substantially annular ring shape, and is substantially identical to the implant or ocular material  430  discussed above. Thus, implant  430  will not be illustrated or discussed in detail when referring to the procedures or methods of FIGS. 54-57. 
     The outer diameter of ocular implant or material  630  can be about 3-9 mm, while the inner opening  632  is generally about 1-8 mm. The thickness of ocular implant  630  is preferably about 20 to about 1000 microns. Ocular implant  630  has a planar face  644  forming a frustoconically shaped surface, which faces inwardly towards the center of eye  610  in a posterior direction of eye  610  to contact the exposed inner surface  620  of the cornea  612 . The opposite face  646  is preferably a curved surface facing in an anterior direction of eye  610  as shown. The ocular implant  630  can be shaped to form a corrective lens or shaped to modify the curvature of the cornea. Similarly, the implant can be used to replace opaque areas of the cornea which have been previously removed by ablation or other means. 
     In the embodiment shown, ocular implant  630  preferably has a substantially uniform shape and cross-section. Alternatively, ocular implant  630  can be any suitable shape having either a uniform and/or non-uniform cross-section in selected areas as necessary to correct the patient&#39;s vision. For example, an ocular implant can be used having a circular or triangular cross section. In this manner, the curvature of a cornea can be modified at selected areas to correct various optical deficiencies, such as, for example, astigmatisms. Ocular implant  630  can be a corrective lens with the appropriate refractive index to correct the vision of the patient. The ocular implant  630  is made from a bio-compatible transparent material. Preferably, ocular implant  630  is made from any suitable transparent polymeric material. Suitable materials include, for example, collagen, silicone, polymethylmethacrylate, acrylic polymers, copolymers of methyl methacrylate with siloxanylalkyl methylacrylates, cellulose acetate butyrate and the like. Such materials are commercially available from contact lens manufacturers. For example, optical grade silicones are available from Allergan, Alcon, Staar, Chiron and Iolab. Optical grade acrylics are available from Allergan and Alcon. A hydrogel lens material consisting of a hydrogel optic and polymethylmethacrylate is available from Staar. 
     Hydrogel ocular implant lenses can be classified according to the chemical composition of the main ingredient in the polymer network regardless of the type or amount of minor components such as cross-linking agents and other by-products or impurities in the main monomer. Hydrogel lenses can be classified as (1) 2-hydroxyethyl methacrylate lenses; (2) 2-hydroxyethyl methacrylate-N-vinyl-2-pyrrolidinone lenses; (3) hydrophilic-hydrophobic moiety copolymer lenses (the hydrophilic components is usually N-vinyl-2-pyrrolidone or glyceryl methacrylate, the hydrophobic components is usually methyl methacrylate); and (4) miscellaneous hydrogel lenses, such as lenses with hard optical centers and soft hydrophilic peripheral skirts, and two-layer lenses. 
     Alternatively, ocular implant  630  can be elongated or arcuate shaped, disc shaped or other shapes for modifying the shape and curvature of cornea  612  or for improving the vision of eye  610  without modifying the curvature of cornea  612 . Similarly, ocular implant  630  can be placed in the intrastromal area of the cornea  612  at a selected area to modify the curvature of the cornea and correct the vision provided by the cornea and lens system. In the embodiment shown in FIGS. 54-57, thin layer  618  of cornea  612  is completely removed to expose the internal surfaces  622  and  624  of cornea  612 . 
     Embodiment of FIG. 58 
     An alternative method of implanting ocular material or implant  630  into an eye  710  is illustrated in FIG.  58 . Specifically, ocular material or implant  630  is implanted into cornea  712  of eye  710  to modify the patient&#39;s vision. In particular, this method can be utilized for the treatment of hyperopia, myopia or removal of opaque portions of the cornea. As in the previous embodiments, the treatment of eye  510  is accomplished without freezing cornea  512  or any portion thereof. 
     In this method, a ring or annular incision  718  is formed in cornea  712  utilizing a scalpel, laser or any cutting mechanism known in the art. The scalpel, laser or cutting mechanism can then be used to cut or ablate an annular-shaped intrastromal pocket  726  in cornea  712  as needed and/or desired. Accordingly, an annular groove is now formed for receiving ocular material or implant  630  which is discussed above in detail. 
     The annular groove formed by annular incision  718  separates cornea  712  into first and second opposed internal surfaces  722  and  724 . First internal surface  722  faces in the posterior direction of eye  710 , while second internal surface  724  faces in the anterior direction of eye  710 . optionally, either internal surfaces  722  or  724  can be ablated to make the annular groove or pocket  726  larger to accommodate ocular implant  630 . 
     The portion of cornea  712  with internal surface  722  forms an annular flap  725 , which is then lifted and folded away from the remainder of cornea  712  so that ocular implant of material  630  can be placed into annular pocket  726  of cornea  712  as seen in FIG.  58 . Now, corneal flap  725  can be folded over ocular implant or material  630  and reconnected to the remainder of cornea  712  via sutures or the like. Accordingly, ocular implant or material  630  is now encapsulated within cornea  712 . 
     As in the previous embodiments, ocular implant or material  630  can modify the curvature of the exterior surface of cornea  712  so as to either increase or decrease its curvature, or maintain the curvature of the exterior surface of cornea  712  at its original curvature. In other words, ocular implant or material  630  can modify the patient&#39;s vision by changing the curvature of the cornea  712  and/or removing opaque portions of the cornea and/or by acting as a corrective lens within the cornea. 
     Embodiment of FIG. 59 
     Another embodiment of the present invention is illustrated utilizing ocular implant  630  in accordance with the present invention. More specifically, the method of FIG. 59 is substantially identical to the methods discussed above in reference to FIGS. 54-57, and thus, will not be illustrated or discussed in detail herein. Rather, the only significant difference between the methods discussed regarding FIGS. 54-57 and the method of FIG. 59 is that the thin layer  816  of FIG. 59 is not completely removed from cornea  812  of eye  810 . 
     In other words, thin layer  818  of cornea  812  is formed by using a scalpel or laser such that a portion of layer  818  remains attached to the cornea  812  to form a corneal flap. The exposed inner surface  820  of layer  818  or the exposed internal surface  824  of the cornea can be ablated or cut with a laser or cutting mechanism as in the previous embodiments to modify the curvature of the cornea. Ocular implant  630  can then be placed between internal surfaces  820  and  824  of cornea  812 . The flap or layer  818  is then placed back onto the cornea  812  and allowed to heal. Accordingly, ocular implant  630  can increase, decrease or maintain the curvature of eye  810  as needed and/or desired as well as remove opaque portions of the eye. 
     Embodiment of FIGS. 60 and 61 
     Referring now to FIGS. 60 and 61, an ocular implant or material  930  in accordance with the present invention is illustrated for treatment of hyperopia or myopia. In particular, ocular implant or material  930  is a disk shape member, which is as thin as paper or thinner. Ocular implant or material  930  includes a center opening  932  for allowing intrastromal fluids to pass between either sides of ocular implant or material  930 . Basically, ocular implant or material  930  is constructed of a suitable transparent polymeric material utilizing diffractive technology, such as a Fresnel lens, which can be utilized to correct the focus of the light passing through the cornea by changing the refractive power of the cornea. Since ocular implant or material  930  is very thin, i.e., as thin as paper or thinner, the exterior surface of the cornea will substantially retain its original shape even after ocular implant or material  930  is inserted into the cornea. Even if there is some change in the cornea, this change can be compensated by the refractive powers of the ocular implant or material  930 . 
     Ocular implant or material  930  can be inserted into the cornea in any of the various ways disclosed in the preceding embodiments. In particular, ocular implant or material  930  can be inserted through a relatively small opening formed in the cornea by folding the ocular implant or material  930  and then inserting it through the small opening and then allowing it to expand into a pocket formed within the intrastromal area of the cornea. Moreover, a thin layer or flap could be created for installing ocular implant or material  930  as discussed above. 
     The outer diameter of ocular implant or material  930  is preferably in the range of about 3.0 mm to about 9.0 mm, while center opening  932  is preferably about 1 mm to about 8.0 mm depending upon the type of vision to be corrected. In particular, ocular implant  930  can be utilized to correct hyperopia and/or myopia when using a relatively small central opening  932  such as in the range of to about 1.0 mm to about 2.0 mm. However, if the opening is greater than about 2.0 mm, then the ocular implant or material  930  is most likely designed to correct imperfections in the eye such as to correct stigmatisms. In the event of astigmatism, only certain areas of the ocular implant  930  will have a refractive index which is different from the intrastromal tissue of the cornea, while the remainder of ocular implant or material  930  has the same refractive index as the intrastromal tissue of the cornea. 
     Preferably, ocular implant  930  is made from a biocompatible transparent material which is resilient such that it can be folded and inserted through a small opening in the cornea and then allowed to expand back to its original shape when received within a pocket in the cornea. Examples of suitable materials include, for example, substantially the same set of materials discussed above when referring to ocular implant or material  430  or  630  discussed above. 
     While various advantageous embodiments have been chosen to illustrate the invention, it will be understood by those skilled in the art that various changes and modifications can be made therein without departing from the scope of the invention as defined in the appended claims.