Surgery – Instruments – Light application
Reexamination Certificate
1999-04-07
2001-06-12
Leubecker, John P. (Department: 3739)
Surgery
Instruments
Light application
C606S004000, C606S010000, C606S013000, C128S898000
Reexamination Certificate
active
06245059
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention generally relates to laser eye surgery, and in particular, provides methods, devices, and systems for selectively ablating corneal tissue to improve the vision of patients having corneal irregularities.
Laser eye surgery systems and methods are now used to correct defects in vision using a technique known as ablative photodecomposition. In general, these techniques selectively expose the cornea to laser radiation so as to selectively remove and resculpt the cornea and achieve a desired change in shape of the cornea to treat an optical defect.
Laser eye surgery is now being used to treat a variety of vision defects, including myopia (nearsightedness), hyperopia (farsightedness), and symmetrical cylindrical astigmatisms. To achieve these results, known laser eye surgery systems make use of a variety of mechanisms to selectively expose the corneal tissue to the ablative laser energy so as to change the optical characteristics of the eye uniformly throughout the optically used portion of the cornea. Often times, the desired change in shape is effected by selectively removing corneal tissue according to a spherical ablation profile (for example, for treatment of myopia and hyperopia). Cylindrical astigmatism is often treated by selectively removing corneal tissue according to a cylindrical profile, in which the cylinder extends laterally across the optical axis of the eye.
Many patients suffer from optical defects which are not easily treated using known spherical or cylindrical ablation techniques. It has been proposed to treat patients suffering from nonsymmetrical or other types of astigmatism by defining a custom ablation profile. Ophthalmic measurement techniques which may be capable of generating highly accurate topographic information on a particular cornea are now being developed. Unfortunately, integrating these topographic measurements together with new ablation algorithms may take years. In the meantime, patients having irregular corneal defects which significantly limit their vision are in need of treatment today.
In light of the above, it would be desirable to provide improved laser eye surgery devices, systems, and methods. It would be beneficial if these improvements allowed the treatment of irregular corneal defects, particularly if these benefits were available and safe for use in the near-term.
2. Description of the Background Art
The following patents and patent applications may be relevant to the present invention: U.S. Pat. No. 5,683,379, issued Nov. 4, 1997, for “Apparatus for Modifying the Surface of the Eye Through Large Beam Laser Polishing and Method of Controlling the Apparatus”, U.S. Pat. No. 4,724,522, issued Feb. 9, 1988, for “Method and Apparatus for Modification of Corneal Refractive Properties”, U.S. Pat. No. 5,098,426, issued Mar. 24, 1992, for “Method and Apparatus for Precision Laser Surgery”, U.S. Pat. No. 5,290,272, issued Mar. 1, 1994, for “Method for the Joining of Ocular Tissues Using Laser Light”, U.S. Pat. No. 5,314,422, issued May 24, 1994, for “Equipment for the Correction of Presbyopia by Remodelling the Corneal Surface by Means of Photo-Ablation”, U.S. Pat. No. 5,391,165, issued Feb. 21, 1995, for “System for Scanning a Surgical Laser Beam”, U.S. Pat. No. 5,439,462, issued Aug. 8, 1995, for “Apparatus for Removing Cataractous Material”, U.S. Pat. No. 5,549,596, issued Aug. 27, 1996, for “Selective Laser Targeting of Pigmented Ocular Cells”, U.S. Pat. No. 5,549,597, issued Aug. 27, 1996, for “In Situ Astigmatism Axis Alignment”, U.S. Pat. No. 5,556,395, issued Sep. 17, 1996, for “Method and System for Laser Treatment of Refractive Error Using an Offset Image of a Rotatable Mask”, U.S. Pat. No. 5,634,919, issued Jun. 3, 1997, for “Correction of Strabismus by Laser-Sculpting of the Cornea”, U.S. Pat. No. 5,637,109, issued Jun. 10, 1997, for “Apparatus for Operation on a Cornea Using Laser-Beam”, PCT International Application No. PCT/EP95/01287, filed Apr. 7, 1995, for “Method and Apparatus for Providing Precise Location of Points on the Eye”, European Patent Application No. 94303256.5, filed May 5, 1994, for “Method and System for Laser Treatment of Refractive Errors Using Offset Imaging”, U.S. patent application Ser. No. 09/274,499, filed Mar. 23, 1999, for “Multiple Beam Laser Sculpting System and Method”. The full disclosure of these references is hereby incorporated by reference.
SUMMARY OF THE INVENTION
The present invention provides improved laser eye surgery devices, systems, and methods. The invention provides near-term customized ablation capabilities for treatment of corneal irregularities by ablating standard refractive therapy profiles at a position which is offset from the pupillary center. These treatment profiles may, when centered on the eye, be suitable for treatment of standard refractive errors such as myopia, hyperopia, and symmetrical cylindrical astigmatism. By selectively offsetting one or more of these ablation profiles at selected points across the corneal surface, the laser system can reduce refractive errors resulting from corneal irregularities such as irregular astigmatism, corneal steepening in one quadrant, asymmetrical astigmatism, irregularities inadvertently produced by a prior refractive treatment (such as radial keratotomy incisions, a decentered ablation, asymmetric warpage as a result of corneal transplants, penetrating keratoplasty, or the like), granular dystrophy, diffuse, bilateral keratoconus, or the like.
In a first aspect, the invention provides a method for treating an eye of a patient. The eye has a cornea and a pupil, the pupil having a center. The method comprises aligning a laser delivery system with the pupil of the eye. A treatment center on the cornea is designated so that the treatment center is offset laterally (in the X and/or Y direction) from the center of the pupil. A region of the cornea is ablated by directing laser energy according to a therapy profile centered at the treatment center, which may be at some distance from the pupillary center.
The therapy may further comprise selecting the therapy profile from a library including a myopic treatment profile, a hyperopic treatment profile, and a cylindrical treatment profile. These treatment profiles may be scaled for both size and power, and still further therapy profiles may be included in the library. A more complete library may include myopic ablations which are spherical, cylindrical, and/or elliptical in shape; hyperopic ablations which are spherical, cylindrical, and/or provide smooth transition zones; and optionally including therapeutic ablations such as phototherapeutic keratectomy slits and/or phototherapeutic keratectomy circles of variable sizes and having variable transition zones.
Corneal irregularities will often benefit from combinations of two or more therapy profiles centered at different treatment centers on the cornea. By providing a variety of different treatment profiles which can be scaled and selectively offset from each other, often at least partially overlapping on the corneal surface, a wide variety of customized contoured ablations may be effected without having to generate individual customized ablation algorithms to effect the desired overall treatment profile.
The particular profile or profiles applied to a patient's eye will often be identified or planned using a map of the cornea. Elevation maps, such as those which might be produced using wavefront technology now under development, are particularly beneficial for selecting, scaling, and offsetting the therapy profiles over the corneal surface to mitigate the corneal irregularity. Advantageously, it is not necessary to (although it is possible to) link these developmental topography systems to the ablation system to generate customized therapies. Instead, a system operator may select individual ablation size, shape, location, and power based on a topography map, so as to plan the total combined treatment, optionally simulating the effect of the proposed ablation before it is
Barrish, Esq. Mark D.
Farah Agned
Leubecker John P.
Townsend & Townsend & Crew LLP
VISX Incorporated
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