Abstract
A system and method for performing a femto-fragmentation procedure on tissue in the crystalline lens of an eye requires that a laser beam be directed and focused to a focal point in the crystalline lens of the eye. The focal point is then guided, relative to an axis defined by the eye, to create a segment cluster by causing Laser Induced Optical Breakdown (LIOB) of tissue in the crystalline lens. The resultant segment cluster includes a plurality of contiguous, elongated segments in the crystalline lens that are individually tapered from an anterior end-area to a posterior end-area. Specifically, this is done to facilitate the removal of individual segments from the segment cluster in the crystalline lens.
Claims
1. A system for performing a femto-fragmentation lensectomy procedure on tissue in the crystalline lens of an eye which comprises: a laser unit for generating a laser beam; a computer connected with the laser unit for directing the laser beam along a beam path to a focal point in the crystalline lens of the eye wherein the lens has a thickness and defines an axis, and the beam path and the focal point are established relative to the axis defined by the lens; a computer generated template pattern, wherein the template pattern is oriented relative to the axis; a controller connected with the computer for moving the focal point relative to the axis defined by the lens, to cause a Laser Induced Optical Breakdown (LIOB) of tissue in the crystalline lens at the focal point to create a plurality of contiguous, elongated, individual segments in the crystalline lens, wherein each individual segment is aligned axially in the lens and individually extends through a length of approximately 80% of the thickness of the lens between a respective anterior end area characterized by a dimension s.sub.a, and a respective posterior end-area characterized by a corresponding dimension s.sub.p, and wherein each segment is tapered from the anterior end-area toward the posterior end-area (s.sub.a>s.sub.p); and an aspirator for sequentially removing the-created individual segments of the crystalline lens from the eye.
2. The system recited in claim 1 wherein the anterior end-area is shaped as a rectangle and the characteristic dimension s.sub.a of the anterior end-area is a side distance of the rectangle.
3. The system recited in claim 2 wherein the characteristic dimension s.sub.a is less than three hundred and fifty microns (s.sub.a<350 m).
4. The system recited in claim 1 wherein the anterior end-area is a square.
5. The system recited in claim 1 wherein the characteristic dimension s.sub.p of the posterior end-area is less than ninety percent of the characteristic dimension s.sub.a of the anterior end-area (s.sub.p<0.9s.sub.a).
6. The system recited in claim 1 wherein the crystalline lens has an exterior surface, and a predetermined volume of tissue, and wherein the tissue for LIOB within the crystalline lens is more than a selected distance from the exterior surface of the crystalline lens to establish a safety margin therebetween.
7. The system recited in claim 6 wherein the safety margin is greater than approximately 50 microns.
8. A system for performing a femto-fragmentation fensectomy procedure on tissue in the crystalline lens of an eye which comprises: a laser unit for directing a laser beam along a beam path to a focal point in the crystalline lens of the eye, wherein the lens has a thickness and defines an axis and the beam path and the focal point are established relative to the axis defined by the lens; a template having a template pattern for defining a plurality of contiguous, elongated, individual segments in the crystalline lens wherein each individual segment is aligned axially in the lens and individually extends through a length of approximately 80% of the thickness of the lens between a respective anterior end-area characterized by a dimension s.sub.a, and a respective posterior end-area characterized by a corresponding dimension s.sub.p, and wherein each segment is tapered from the anterior end-area toward the posterior end-area (s.sub.a>s.sub.p); a computer connected to the laser unit for guiding the focal point of the laser beam with reference to the axis and to a computer-generated template pattern to cause a Laser Induced Optical Breakdown (LIOB) of tissue in the crystalline lens at the focal point; and an aspirator for sequentially removing the plurality of individual segments of the crystalline lens from the eye.
9. The system recited in claim 8 wherein the template pattern is oriented relative to the axis and the focal point of the laser beam is moved in accordance with the template pattern.
10. The system recited in claim 8 wherein the anterior end-area is shaped as a rectangle and the characteristic dimension s.sub.a of the anterior end-area is a side distance of the rectangle.
11. The system recited in claim 10 wherein the anterior end-area is a square.
12. The system recited in claim 11 wherein the characteristic dimension s.sub.a is less than three hundred and fifty microns (s.sub.a<350 m).
13. The system recited in claim 8 wherein the anterior end-area is shaped as a triangle.
14. The system recited in claim 8 wherein the characteristic dimension s.sub.p of the posterior end-area is less than ninety percent of the characteristic dimension s.sub.a of the anterior end-area (s.sub.p<0.9s.sub.a).
15. The system recited in claim 8 wherein the crystalline lens has an exterior surface and a predetermined volume of tissue within the crystalline lens, wherein the predetermined volume of tissue is more than a selected distance from the exterior surface of the crystalline lens to establish a safety margin therebetween.
16. The system recited in claim 15 wherein the safety margin is greater than approximately 50 microns.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) The novel features of this invention, as well as the invention itself, both as to its structure and its operation, will be best understood from the accompanying drawings, taken in conjunction with the accompanying description, in which similar reference characters refer to similar parts, and in which:
(2) FIG. 1 is a schematic view of the components of the system for the present invention;
(3) FIG. 2 is a profile view of a crystalline lens;
(4) FIG. 3 is a perspective view of a segment cluster as would be created inside the crystalline lens of an eye in accordance with the present invention;
(5) FIG. 4A is a plan view of a template having a pathway pattern for guiding a laser beam in accordance with the present invention;
(6) FIG. 4B is a plan view of an embodiment of another template having an alternate pathway pattern for guiding a laser beam in accordance with the present invention;
(7) FIG. 5 is a side elevation view of a lens segment that would be created in accordance with the present invention using a template as shown in FIG., 4A;
(8) FIG. 6 is a side elevation view, in cross section, of a segment cluster, as would be seen along the line 6-6 in FIG. 4A, with portions of segments already removed and with another individual segment in the process of being removed from the cluster during a lensectomy;
(9) FIG. 7 is a profile view of a crystalline lens showing an incision pattern for creating a segment cluster to facilitate removal of lens material from the posterior of the lens; and
(10) FIG. 8 is a perspective view of a segment cluster as would be created inside the crystalline lens of an eye in accordance with the present invention to facilitate removal of lens material from the posterior of the lens.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
(11) Referring initially to FIG. 1, a system in accordance with the present invention is shown and is generally designated 10. As shown, the system 10 essentially includes a laser unit 12 and a controller/computer 14. In combination, the computer/controller 14 is connected with the laser unit 12 for the purposes of guiding and controlling the movement of a laser beam 16 that is generated and focused by the laser unit 12. Necessarily, the laser unit 12 is of a type that generates a pulsed laser beam 16 which is capable of performing Laser Induced Optical Breakdown (LIOB) on anatomical tissue. Preferably, the laser beam 16 will have laser pulses with pulse durations in the femtosecond range.
(12) As indicated in FIG. 1, the system 10 of the present invention is primarily intended to be used for ophthalmic operations on the crystalline lens 18 of an eye 20. More specifically, the present invention envisions a use for the laser unit 12 that involves breaking-up, or fragmenting, the crystalline lens 18 in preparation for a subsequent lensectomy. When a femtosecond laser is used for such a purpose (i.e. laser unit 12), the operation is often referred to as a femto-fragmentation procedure.
(13) In an operational context for the present invention, as shown in FIG. 2, an axis 22 is defined by the crystalline lens 18. As a practical matter, the axis 22 will be established as a reference datum for the system 10 and it may conveniently be based on a selected optical axis of the eye 20. Also, the crystalline lens 18, itself, has an exterior surface 24 that acts as a reference datum. With these data in mind, a tissue volume 26, which is located inside the crystalline lens 18, is diagnostically identified for lens fragmentation during a lensectomy. For safety reasons, the tissue volume 26 may be located generally within a boundary 28 that is clinically identified to establish a safety margin 30.
(14) In general, FIG. 2 shows that the tissue volume 26 will be centered on the axis 22, and it will be oriented substantially symmetric with the axis 22. Further, the safety margin 30 which surrounds the tissue volume 26 will typically be at least fifty microns in depth. Within the defined tissue volume 26, cuts 32 can then be made into the crystalline lens 18, inside the safety margin 30, by the laser unit 12. As indicated above, these cuts 32 into tissue of the crystalline lens 18 will result from a Laser Induced Optical Breakdown (LIOB) of the tissue which occurs at the focal point of the laser beam 16.
(15) In accordance with the present invention, the cuts 32 into the crystalline lens 18 are made to create a segment cluster 34, such as the one shown in FIG. 3. In particular, a segment cluster such as the segment cluster 34 results when the laser beam 16 that is generated by the laser unit 12 is moved in accordance with a template pattern 36 shown in FIG. 4A. In each case, it is to be appreciated that other template patterns can be used for the same purpose. For instance, the pattern 38 that is shown in FIG. 4B is an example of such an alternate template pattern. With this in mind, the particular configuration for a segment cluster 34 will depend on the pattern that is used (e.g. template pattern 36 for squares and template pattern 38 for triangles). Typically, as implied above, these patterns 36/38 will be computer-generated by the controller/computer 14.
(16) In detail, the segment cluster 34 that is shown in FIG. 3 includes a plurality of contiguous individual segments 40 (i.e. rods), which are each essentially equivalent to the exemplary segment 40 shown in FIG. 5. In this plurality, each segment 40 (rod) is elongated, and each has an anterior end 42 and a posterior end 44. Further, for the exemplary segment 40, the anterior end 42 of the segment 40 will be in the shape of a square that defines an anterior end-area 46 (see FIG. 4A). Importantly, this end-area 46 will have a dimension s.sub.a that is characteristic of its shape. In the example presented here for discussion, the dimension s.sub.a is the length of a side of the square, anterior end-area 46. It should also be noted that the segment 40 has a posterior end-area 48 which is located at its posterior end 44. This posterior end-area 48 is also square shaped, and its characteristic dimension, which corresponds with the dimension s.sub.a, is the dimension identified as s.sub.p. The present invention, however, envisions there may be shape differences between the anterior end-area 46 and the posterior end-area 48, as well as size and dimension differences.
(17) An important structural aspect of each segment 40 is that it is tapered in the posterior direction. Thus, the end-area 46 of segment 40 is greater than the end-area 48. A consequence of this is that the segment cluster 34, itself, will also be tapered. A functional purpose for this structural configuration is to facilitate a separation between adjacent segments 40 when they are individually pulled in an anterior direction.
(18) Returning to FIG. 3, exemplary dimensions for the segment cluster 34, and thus for the segments 40 also, are indicated. In particular, the segment cluster 34 is shown to be around 6 mm across its anterior surface 50, and around 4 mm across its posterior surface 52. Thus, in this case, s.sub.a of the anterior end-area 46 may be around half again as long as s.sub.p for the posterior end-area 48 of the segment 40 (s.sub.a1.5s.sub.p). FIG. 3 also indicates that s.sub.a for the anterior end-area 46 of each segment 40 (rod) will preferably be around three hundred and fifty microns (350 m). As also indicated, the length of each segment 40 may be about as long as the side 54 of the segment cluster 34 (e.g. approximately 4 mm or 80% of lens thickness). These dimensional relationships, of course, are only exemplary. The physical size of the crystalline lens 18, and the diagnostic evaluation of the crystalline lens 18, will significantly contribute to a determination of these dimensions for the segment 40. In general, however, the characteristic dimension s.sub.p of the posterior end-area 48 is preferably less than ninety percent of the corresponding characteristic dimension s.sub.a of the anterior end-area 46 (s.sub.p<0.9s.sub.a).
(19) In FIG. 6, the removal of a segment 40 from a segment cluster 34, as envisioned for the present invention, is operationally depicted during a lensectomy. Specifically, as shown, a phaco-needle 56 is being used to aspirate the segment 40. In this operation it is important that the lumen 58 of the phaco-needle 56 be dimensioned to receive the segment 40. In particular, it is necessary that the dimension s.sub.a for the anterior end-area 46 of the segment 40 be such that the lumen 58 is able to accommodate the anterior end-area 46 of the segment 40. With such an accommodation, the segment 40 can be removed from the segment cluster 34.
(20) Importantly, as disclosed above, the segment 40 is appropriately tapered to facilitate its removal from the segment cluster 34. Although entire segments 40 may be removed intact, the segments 40 (s.sub.a) and 40 (s.sub.a) are shown in FIG. 6 to illustrate the fact that partial segments 40 and 40 may sometimes result during a lensectomy. Specifically, this may happen because there are so-called fracture planes within the crystalline lens 18, along which tissue of the crystalline lens 18 may be weak and subject to separation. Operationally, these fracture planes may be further weakened by the LIOB of adjacent tissue during lens fragmentation. In the event, the fracture lines will typically align substantially perpendicular to the axis 22, and thereby further facilitate the removal of segments 40. Regardless, the consequence of this is that shorter segments 40 and 40 and complete segments 40 can be removed with similar ease.
(21) FIG. 7 shows another implementation in which a crystalline lens 18 is incised to create a segment cluster 34 to facilitate removal of lens material from the posterior of the crystalline lens 18. As shown in FIG. 7, an axis 22 is defined by the crystalline lens 18 that can be used to establish a reference datum and the crystalline lens 18 has an exterior surface 24 that can also act as a reference datum. Also, crystalline lens 18 includes a posterior side 60 and an anterior side 62. In addition, as shown, a tissue volume 26 is located inside the crystalline lens 18 that can be diagnostically identified for lens fragmentation during a lensectomy. As discussed above, the tissue volume 26 may be located generally within a boundary 28 that is clinically identified to establish a safety margin 30.
(22) Continuing with FIG. 7, it can be seen that the tissue volume 26 can be centered on the axis 22, and can be oriented substantially symmetric with the axis 22. Within the tissue volume 26, cuts 32 can then be made into the crystalline lens 18 and inside the safety margin 30 by the laser unit 12 (FIG. 1). As indicated above, these cuts 32 into tissue of the crystalline lens 18 can result from a Laser Induced Optical Breakdown (LIOB) of the tissue which occurs at the focal point of the laser beam 16 (FIG. 1).
(23) As best seen in FIG. 8, the cuts 32 into the crystalline lens 18 (FIG. 7) can be patterned to create a segment cluster 34. More specifically, the segment cluster 34 can be achieved when the laser beam 16 (FIG. 1) that is generated by the laser unit 12 is moved in accordance with a template pattern for squares, rectangles, or triangles (as discussed above). FIG. 8 shows LIOB paths (of which LIOB paths 64a-c are labeled) to create the segment 40a.
(24) Continuing with FIG. 8, it can be seen that the segment cluster 34 includes a plurality of contiguous individual segments 40 (i.e. elongated rods) with each segment 40 having an anterior end 42 and a posterior end 44. Further, for the exemplary segments 40 shown, the anterior end 42 of the segment 40 can be in the shape of an arcuate sided rectangle that defines an anterior end-area 46. For the segments 40 shown, the end-area 46 will have a dimension s.sub.a that is characteristic of its shape and size. For example, the dimension s.sub.a can be calculated as the area of the arcuate sided rectangle. FIG. 8 also shows that the segment 40 has a posterior end-area 48 which is located at its posterior end 44. This posterior end-area 48 is also shaped as an arcuate sided rectangle, and its characteristic dimension, which corresponds with the dimension s.sub.a is the dimension identified as s.sub.p.
(25) The present invention, however, envisions there may be shape differences between the anterior end-area 46 and the posterior end-area 48, as well as size and dimension differences.
(26) For the embodiment illustrated by FIGS. 7 and 8, each segment 40 is tapered in the anterior direction. Thus, the end-area 48 of segment 40 is greater than the end-area 46 (i.e. s.sub.p>s.sub.a). A consequence of this is that the segment cluster 34, itself, will also be tapered. A functional purpose for this structural configuration is to facilitate a separation between adjacent segments 40 when they are individually pulled in a posterior direction.
(27) While the particular System And Method For Femto-Fragmentation Of A Crystalline Lens as herein shown and disclosed in detail is fully capable of obtaining the objects and providing the advantages herein before stated, it is to be understood that it is merely illustrative of the presently preferred embodiments of the invention and that no limitations are intended to the details of construction or design herein shown other than as described in the appended claims.
