Surgery – Instruments – Light application
Reexamination Certificate
1999-07-14
2002-04-02
Buiz, Michael (Department: 3731)
Surgery
Instruments
Light application
C606S004000
Reexamination Certificate
active
06364871
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to systems, methods and devices for sculpturing a laser beam. More particularly, the invention relates to a device located in the path of a laser for blocking or occluding a portion of the laser beam in accordance with a predetermined pattern wherein the portion of the laser beam reaching the target may be varied, and to methods for using such a device. The use of lasers to alter the surface of objects is becoming more important as it becomes apparent that lasers may be precisely focused and the amount of energy transferred to the target can be closely controlled. Lasers have been used in eye surgery, for example, to treat the retinae of diabetic persons. Lasers have also been used by doctors for other precise and delicate eye surgery.
In all of the prior art eye surgery procedures, as well as in other efforts to use laser beam pulses to act on or burn away tissue or other matter, a great concern arises about the ability to control the size and intensity of the beam. In addition, when multiple treatment pulses are intended, precise location and shaping of the beam is desirable.
BACKGROUND OF THE INVENTION
Until recently, it has not been possible to provide a practical predetermined pattern of treatment where the intensity and duration of the laser pulse is controlled while simultaneously controlling the shape of the laser pulse and the location where the pulse strikes the target. It has been found that the cornea of the eye may be shaped or otherwise treated with a laser beam pulse in a plurality of locations on the eye to achieve a desired result. Until now, however, the ability to control the size, shape and location of the beam has been undesirably limited. It has recently been discovered that predetermined control of the laser beam pulse may be accomplished by passing the laser beam through an iris that is centered on both the axis of the laser beam and on the optical axis of the cornea. By controlling the size of the iris opening and simultaneously controlling the amount of laser energy passing through the iris aperture, the surface curvature of the eye can be changed to correct for myopia or near sightedness. Such a procedure, however, has not found widespread acceptance due to inherent limitations in beam shape and size that an aperture of this type provides. For example, the use of an iris only permits a round, symmetrical alteration in laser beam shape that is not useful for treatment of astigmatism, hyperopia, irregular shapes and even repair of over corrected or inaccurate corrections for myopia.
Treatment for hyperopia by means of a laser necessarily involves the removal of more corneal tissue at the periphery as compared to the center region of the cornea. As a result, the use of only a variable iris-type aperture to alter the shape of a laser beam cannot accomplish this purpose. Teachings in the prior art, such as Yoder, Jr. U.S. Pat. No. 5,219,344, disclose the use of annuli of varying size to effect a greater exposure of peripheral corneal tissue. Notably, however, the methods and apparatus described in Yoder, Jr. also inherently require the use of shapes that are symmetrical about the axis of the laser beam and about the optical axis of the cornea. These methods are therefore inherently limited by the use of aperture discs having a limited number of annuli. Further, the inability to vary the shape of such annuli imposes additional limitations upon the operator as this inability limits the extent to which the cross-sectional shape of the laser beam can be modified.
Similarly, Trokel U.S. Pat. No. 5,108,388 describes a laser surgery method which employs masks having limited numbers of circular or slit-shaped apertures. The inherent limitations in such a method is similar to that of Yoder, Jr. More specifically, while Trokel teaches that any suitable number of openings can be formed in the masks, the cross-sectional shape of the laser beam is nonetheless limited by the specific openings so provided. As a result, the flexibility desired in treating any given curvature malformation or combination of curvature malformations cannot be achieved.
In a more telling example of the limitations of the prior art, the treatment of hyperopia combined with an astigmatism presents an even further complicated problem as tissue not only from the periphery but also along the major axis of the astigmatism must by preferentially removed compared with other regions of the cornea. The methods and apparatus of Yoder, Jr. have significant disadvantages when applied to such a procedure as two different aperture discs, one applicable to hyperopia and one applicable to astigmatism, must be used in conjunction. More importantly, and as above, the aperture discs contain a limited number of apertures from which to select in shaping the cross-sectional area of the laser beam applied to the cornea. As a result, to the extent the procedure can even be performed by the methods and apparatus of Yoder, Jr., inferior results are inevitably obtained.
The teachings of Shimmick, et al. U.S. Pat. No. 5,549,597, while overcoming certain of the disadvantages of Yoder, Jr., is limited in its applicability. Shimmick, et al., which applicants note is not necessarily prior art to the present invention, teaches a device which has variable cylinder blades which are useful in the treatment of astigmatisms. This usefulness is limited, however, as the operation of the cylinder blades cannot provide an effective treatment of hyperopia or an astigmatism combined with hyperopia. Moreover, insofar as the teachings of Shimmick, et al. are silent with respect to either independent movement of the cylinder blades or movement of the cylinder blades asymmetric to the center line of the iris, it fails to overcome many of the limitations found in the prior art.
OBJECTS OF THE INVENTION
In view of the deficiencies and disadvantages of the prior art as recognized by applicants, it is an object of the present invention to provide a system, method and device for sculpturing the shape of a laser beam to change the shape of the beam that impacts its intended target.
Another object of this invention is to provide a system, method and device which is useful in sculpturing laser beams into asymmetrical laser beam subportions, including shapes that are not round.
Yet another object of the present invention is to provide a system, method and device capable of shaping a laser beam to permit treatment of astigmatism, hyperopia, irregular shapes and even repair of over corrected or inaccurate corrections for myopia.
SUMMARY OF THE INVENTION
It has been unexpectedly found that the systems, methods and devices of the present invention overcome the limitations of the prior art, without adding unnecessary complexity. More specifically, applicants have found that it superior results in the shaping of a cornea can be achieved by using methods and devices which expose a plurality of corneal regions to a plurality of asymmetrical laser beam subportions to affect the shape of said cornea without introducing any substantial asymmetry to the shape of said cornea. Thus, applicants have discovered that by abandoning the teachings of the prior art which rely on laser beam shapes that are substantially symmetrical about the laser beam axis, methods and devices of substantially superior flexibility, economy and practicality can be realized. Accordingly, preferred method aspects of the present invention comprise providing a laser beam having an predefined shape along a beam axis and exposing a plurality of corneal regions to a plurality of asymmetrical laser beam subportions to affect the shape of said cornea without introducing any substantial asymmetry to the shape of said cornea. As used herein, the term “asymmetrical laser beam subportions” refers to portions of the laser beam which are not symmetrical about the axis of the laser beam. According to preferred embodiments, the cross sectional shape of the laser beam subportion is substantially defined by a portion of the periphery of said predefined
Berlin Gregory
Rozakis George
Sotiropoulos Nicholas
Apollo Vision, Inc.
Buiz Michael
Synnestvedt & Lechner LLP
Woo Julian W.
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