BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings, wherein like reference numerals refer to similar components:
FIG. 1 is a top plan view of a cornea and the incisions made therein;
FIG. 2 is a sectional view of the cornea of FIG. 1 along the line 2-2;
FIG. 3 is a top plan view of donor tissue grafted into a recipient cornea; and
FIG. 4 is a schematic view of a system for resecting corneal tissue.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Turning in detail to the drawings, FIG. 1 illustrates the incisions made in a cornea 11 as part of a full thickness corneal transplant procedure. The same incisions are made in both the recipient cornea and the donor cornea. The sidecut incision 13 is made through the full thickness of the cornea 11. However, if a lamellar corneal transplant is performed, then the sidecut is made to the depth of the resection incision made within the stroma. In this instance, where the sidecut incision 13 is a full thickness incision, it enables resection of the corneal tissue 15 from the cornea 11. While the sidecut incision shown is a simple incision running straight from the anterior corneal surface to the posterior corneal surface, more complex sidecut incisions may also be used. Four crosscut incisions 17 are shown, and although any number of crosscut incisions may be used, at least two are preferred, with four or more being more preferred. Preferably, multiple crosscut incisions are equally spaced apart along the sidecut incision.
FIG. 2 shows the depth of the crosscuts 17 as compared to the full thickness of the cornea 11. These crosscuts 17 are located at the anterior corneal surface 19 and are deep enough so that the surgeon can easily locate them when performing the graft. The actual depth of the crosscuts 17 may therefore vary depending upon the particular preferences of the attending surgeon. The length of the crosscuts 17 also depends upon the preferences of the attending surgeon. The crosscuts 17 should extend on either side of the sidecut 15 so that the surgeon can easily locate them when performing the graft. Optionally, the crosscuts may be disposed within the stroma, below the epithelium, and need not extend to the anterior corneal surface. This is also left up to the preferences of the attending surgeon.
FIG. 3 shows donor tissue 19 grafted in place within the recipient cornea 21. As indicated above, the positioning of the partial crosscuts 23, 25 within the donor tissue 19 and the recipient tissue 21 facilitates alignment of the two tissues. The amount which these partial crosscuts 23, 25 extend beyond the sidecuts 27, 29 in each of the donor tissue and the recipient cornea, respectively, facilitates placement of sutures. Additionally, a dye or stain, such as those which are well known to skilled artisans, may be used to assist the surgeon in locating and aligning the crosscuts. One suture is preferably placed at the location of each pair of partial crosscuts 23, 25. For a given pair of crosscuts 23, 25, the suture may enter the tissue at any point along the length of each partial sidecut 23, 25. This enables the surgeon to place the sutures as near or as far from the sidecuts 27, 29 as desired.
The combination of all incisions made in each of the recipient cornea and the donor cornea form an incision pattern. It is desirable to have the incision pattern in each of the two corneas be identical and symmetrical. Identical and symmetrical incision patterns enable the donor tissue to be placed in one or more orientations within the recipient cornea and greatly facilitates alignment of the crosscuts in the donor tissue with the crosscuts in the recipient cornea. Moreover, an incision pattern which includes symmetry, especially symmetry in the crosscuts, about multiple axes will help reduce the amount of stress any single suture places on the grafted tissue. Such symmetry most commonly results from the crosscuts being placed at equal intervals about the periphery of the sidecut.
Referring to FIG. 4, a femtosecond surgical laser 41 generates a pulsed laser beam 43 and directs that beam into the focusing assembly 45, which in turn focuses the pulsed beam 43 into the cornea 47. The controller 49 is a programmable computer which precisely controls the location of the beam focal point within the cornea 47 according to parameters received from the surgeon interface 51. The interface 51 presents the surgeon with several incision patterns from which the desired sidecut pattern is selected. In addition, the interface 51 presents the surgeon with options for choosing the number of crosscut incisions. Alternatively, the interface 51 may present the surgeon with resection patterns which are pre-configured with crosscuts. The selected options are sent to the controller, and the controller 49 determines the locations of each crosscut along the sidecut pattern for purposes of controlling the focusing assembly and incising the sidecut pattern, along with the crosscuts, in the cornea.
The surgical laser may be of the type described in U.S. Pat. No. 4,764,930, producing an ultra-short pulsed beam as described in one or both of U.S. Pat. No. 5,984,916 and U.S. Pat. No. RE37,585 to photodisrupt corneal tissues. The focusing assembly may be of the type described in U.S. patent application Ser. No. 11/272,571. The disclosures of the aforementioned patents are incorporated herein by reference in their entirety. Commercial laser systems capable of performing the incisions are available from IntraLase Corp. of Irvine, Calif.
When made with a laser, the incisions will be much less than the thickness of the needles that are typically used to place sutures, but they will still be readily visible to the surgeon (although not necessarily with the naked eye), especially if they are at the anterior corneal surface. Thus, the narrow crosscut incisions made by a laser will generally aid the surgeon in precisely locating the suture in the desired position in both the donor tissue and the recipient cornea.
The surgical laser may be used in conjunction with a contact lens (not shown) which is applied to the anterior corneal surface to deform the cornea. Deformation of the cornea in this manner provides multiple advantages which are well known to skilled artisans. For example, U.S. Pat. No. 5,549,632, which is incorporated herein by reference, describes advantages gained in making laser incisions by deforming the shape of the cornea, particularly by application. U.S. Pat. No. 6,863,667 and U.S. patent application Ser. No. 11/258,399, both of which are incorporated herein by reference, describe patient interface devices which deform the cornea and are used to align the surgical laser with the recipient cornea for purposes of making accurate incisions.
Thus, a system and method for marking corneal tissue in a transplant procedure are disclosed. While embodiments of this invention have been shown and described, it will be apparent to those skilled in the art that many more modifications are possible without departing from the inventive concepts herein. The invention, therefore, is not to be restricted except in the spirit of the following claims.
Patent Application
20080058841
