CA2294592A1 - Large beam scanning laser ablation - Google Patents
Large beam scanning laser ablation Download PDFInfo
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- CA2294592A1 CA2294592A1 CA002294592A CA2294592A CA2294592A1 CA 2294592 A1 CA2294592 A1 CA 2294592A1 CA 002294592 A CA002294592 A CA 002294592A CA 2294592 A CA2294592 A CA 2294592A CA 2294592 A1 CA2294592 A1 CA 2294592A1
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F9/00—Methods or devices for treatment of the eyes; Devices for putting-in contact lenses; Devices to correct squinting; Apparatus to guide the blind; Protective devices for the eyes, carried on the body or in the hand
- A61F9/007—Methods or devices for eye surgery
- A61F9/008—Methods or devices for eye surgery using laser
- A61F9/00802—Methods or devices for eye surgery using laser for photoablation
- A61F9/00817—Beam shaping with masks
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F9/00—Methods or devices for treatment of the eyes; Devices for putting-in contact lenses; Devices to correct squinting; Apparatus to guide the blind; Protective devices for the eyes, carried on the body or in the hand
- A61F9/007—Methods or devices for eye surgery
- A61F9/008—Methods or devices for eye surgery using laser
- A61F9/00802—Methods or devices for eye surgery using laser for photoablation
- A61F9/00804—Refractive treatments
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/02—Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam
- B23K26/06—Shaping the laser beam, e.g. by masks or multi-focusing
- B23K26/064—Shaping the laser beam, e.g. by masks or multi-focusing by means of optical elements, e.g. lenses, mirrors or prisms
- B23K26/066—Shaping the laser beam, e.g. by masks or multi-focusing by means of optical elements, e.g. lenses, mirrors or prisms by using masks
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F9/00—Methods or devices for treatment of the eyes; Devices for putting-in contact lenses; Devices to correct squinting; Apparatus to guide the blind; Protective devices for the eyes, carried on the body or in the hand
- A61F9/007—Methods or devices for eye surgery
- A61F9/008—Methods or devices for eye surgery using laser
- A61F2009/00861—Methods or devices for eye surgery using laser adapted for treatment at a particular location
- A61F2009/00872—Cornea
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- Optics & Photonics (AREA)
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- Mechanical Engineering (AREA)
- Plasma & Fusion (AREA)
- Laser Beam Processing (AREA)
Abstract
The present invention provides a method for ablating material including directing a laser beam through a mask and through a scanning unit to an area of the material to thereby ablate the material, wherein the scanning unit can scan or be controlled to scan the beam in a predetermined pattern on the material, and an apparatus for laser ablation of material including a laser source for producing a beam of far ultra-violet or infra-red light, a mask, means for directing the beam through the mask and a computer-controlled scanning unit for scanning or being controlled to scan the beam in a predetermined pattern on the material, wherein the beam is directed to an area of the material to be ablated. The mask may be of variable area, and this area may be increased during a single use of the apparatus.
Description
i LARGE BEAM SCANNING LASER ABLATION
The present invention relates to the laser processing or ablation of materials, and in particular the invention is suitable for use in operations on the corneal tissue of the eye for the correction of myopia, astigmatism and hyperopia, examples of which are refractive correction operations such as photorefractive keratectomy (PRK) and laser in-situ keratomileusis (LASIK). The invention will be described with reference to these operations though it will be appreciated that other applications are possible and envisaged.
The most common laser used for operations on the corneal tissue is the excimer laser operating at a wavelength of 193 nanometres. Whatever the laser source, the laser system needs to control the laser output so that the appropriate shape is etched or ablated into the corneal material. Three distinct systems have evolved to control the laser output necessary to perform this task. The first method uses a large beam capable of ablating a large surface area of between 5 and 10 millimetres. The beam i.s masked off to limit the area of corneal surface exposed (see, for example, U.S. Patent 4,941,093). The mask size and shape is varied during the procedure to control the shape being ablated. Examples of masks include an iris diaphragm, ablated plastic forming an oval, or parallel blades forming an expanding slit. Sometimes the mask consists of shapes cut in spinning disks. The laser beam may also be rotated continuously using an image rotator about its central axis to smooth the ablated surface. The laser beam, after being shaped by the mask, is sometimes then scanned in a fixed pattern, as described in EP 0 628 298 A1 and in Ophthalmic Excimer Lasers:
Principles and Practice, edited by McGee, C., Taylor, H.R., Gartry, D., Trokel, S., Martin Duaitz Limited, London (1997) whew, for example, hyperopia is being corrected.
' . ~ ' ' PCT/AU98/0046~
Received 09 March 1999
The present invention relates to the laser processing or ablation of materials, and in particular the invention is suitable for use in operations on the corneal tissue of the eye for the correction of myopia, astigmatism and hyperopia, examples of which are refractive correction operations such as photorefractive keratectomy (PRK) and laser in-situ keratomileusis (LASIK). The invention will be described with reference to these operations though it will be appreciated that other applications are possible and envisaged.
The most common laser used for operations on the corneal tissue is the excimer laser operating at a wavelength of 193 nanometres. Whatever the laser source, the laser system needs to control the laser output so that the appropriate shape is etched or ablated into the corneal material. Three distinct systems have evolved to control the laser output necessary to perform this task. The first method uses a large beam capable of ablating a large surface area of between 5 and 10 millimetres. The beam i.s masked off to limit the area of corneal surface exposed (see, for example, U.S. Patent 4,941,093). The mask size and shape is varied during the procedure to control the shape being ablated. Examples of masks include an iris diaphragm, ablated plastic forming an oval, or parallel blades forming an expanding slit. Sometimes the mask consists of shapes cut in spinning disks. The laser beam may also be rotated continuously using an image rotator about its central axis to smooth the ablated surface. The laser beam, after being shaped by the mask, is sometimes then scanned in a fixed pattern, as described in EP 0 628 298 A1 and in Ophthalmic Excimer Lasers:
Principles and Practice, edited by McGee, C., Taylor, H.R., Gartry, D., Trokel, S., Martin Duaitz Limited, London (1997) whew, for example, hyperopia is being corrected.
' . ~ ' ' PCT/AU98/0046~
Received 09 March 1999
- 2 -The other two methods involve scanning the beam across the surface of the material to be ablated. The first method involves scanning a long, narrow slit beam across an aperture of masks similar to that used in the large beam method. The configuration of the shape being ablated into the surface is also controlled in a similar fashion to that used to control the large beam method. The last method involves scanning a small beam with a diameter in the range of 2.5 mm or smaller (see U.S. Patent 5,520,679). The shape being ablated is controlled by having the scanned beam pass over the areas to be ablated more often than those areas where less material is required to be removed.
Scanning systems have the advantage that a lower energy laser source is required, with both cost and size advantages. The small beam scanning method also has the advantage that it is easier to control the laser system to ablate any arbitrary shape than it is using masks.
Scanning the laser beam also imparts some of the beam smoothing required for these operations.
The biggest disadvantage with scanning systems is their inability to maintain a uniform tissue hydration over the area being treated. The ablation rate of tissue is strongly related to its state of hydration. Immediately after exposure to the laser the tissue is warm and dry;-and a second laser pulse will ablate more than expected. In the following seconds fluid will well up from deeper tissue so that the surface tissue becomes very hydrated with a layer of fluid on top. In this case the next pulse will ablate much less than expected. Hence it is extremely difficult to create a desired shape, or to predict accurately the profile that a scanning laser will ablate.
Large beam systems have an advantage in that they can expose the whole treated area at once and hence they can AMENDED SHEET lArkicle 34) (IPEA/AiP
coissoasooa.s CA 0 2 2 9 4 5 9 2 19 9 9 - 12 - 15 . . . PCT/AU98/00465 Received 17 August 1999
Scanning systems have the advantage that a lower energy laser source is required, with both cost and size advantages. The small beam scanning method also has the advantage that it is easier to control the laser system to ablate any arbitrary shape than it is using masks.
Scanning the laser beam also imparts some of the beam smoothing required for these operations.
The biggest disadvantage with scanning systems is their inability to maintain a uniform tissue hydration over the area being treated. The ablation rate of tissue is strongly related to its state of hydration. Immediately after exposure to the laser the tissue is warm and dry;-and a second laser pulse will ablate more than expected. In the following seconds fluid will well up from deeper tissue so that the surface tissue becomes very hydrated with a layer of fluid on top. In this case the next pulse will ablate much less than expected. Hence it is extremely difficult to create a desired shape, or to predict accurately the profile that a scanning laser will ablate.
Large beam systems have an advantage in that they can expose the whole treated area at once and hence they can AMENDED SHEET lArkicle 34) (IPEA/AiP
coissoasooa.s CA 0 2 2 9 4 5 9 2 19 9 9 - 12 - 15 . . . PCT/AU98/00465 Received 17 August 1999
3 maintain a uniform tissue hydration level over that area. It can also perform the operation quicker than scanning systems. However, it requires larger and more costly laser sources. The requirement for beam homogeneity is also more important in large beam systems.
It is an object of the present invention, therefore, to provide an improved beam control system that can more accurately and/or predictably ablate a desired shape into a material such as tissue in LASIK and PRK operations, while maintaining some or all of the advantages of both large beam systems and the scanning system.
The invention provides a method for ablating material, including:
directing a pulsed laser beam through variable mask means to produce an incident beam of cross-section predetermined by the mask means; and scanning the incident beam in a predetermined pattern onto the material to thereby ablate the material;
wherein said predetermined cross-section is progressively increased by said mask means during said scanning in said predetermined pattern;
and wherein said predetermined pattern includes multiple selected paths on and around said material, in each of which there are a plurality of pulses of said incident beam.
The invention also provides an apparatus for laser ablation of material including:
a laser source for producing a pulsed laser beam;
variable mask means;
means for directing said beam through said mask means to produce an incident beam of cross-section predetermined by the mask means; and AMENDED SHEET (Article 341 (IPEA/ALn I
corssoasooa.s CA 0 2 2 9 4 5 9 2 19 9 9 - 12 - 15 Received 17 August 1999
It is an object of the present invention, therefore, to provide an improved beam control system that can more accurately and/or predictably ablate a desired shape into a material such as tissue in LASIK and PRK operations, while maintaining some or all of the advantages of both large beam systems and the scanning system.
The invention provides a method for ablating material, including:
directing a pulsed laser beam through variable mask means to produce an incident beam of cross-section predetermined by the mask means; and scanning the incident beam in a predetermined pattern onto the material to thereby ablate the material;
wherein said predetermined cross-section is progressively increased by said mask means during said scanning in said predetermined pattern;
and wherein said predetermined pattern includes multiple selected paths on and around said material, in each of which there are a plurality of pulses of said incident beam.
The invention also provides an apparatus for laser ablation of material including:
a laser source for producing a pulsed laser beam;
variable mask means;
means for directing said beam through said mask means to produce an incident beam of cross-section predetermined by the mask means; and AMENDED SHEET (Article 341 (IPEA/ALn I
corssoasooa.s CA 0 2 2 9 4 5 9 2 19 9 9 - 12 - 15 Received 17 August 1999
4 a computer-controllable scanning unit for scanning said incident beam in a predetermined pattern onto said material to thereby ablate the material;
wherein said mask means is varied to increase said predetermined cross-section as the incident beam is scanned;
and wherein said predetermined pattern includes multiple selected paths on and around said material, in each of which there are a plurality of pulses of said incident beam;
said apparatus further including computer means coupled to or incorporated in said scanning unit and to said mask means for jointly controlling both, said computer means having an installed program for effecting said predetermined scanning pattern and for varying said mask means to progressively increase said predetermined cross-section during said scanning in said predetermined pattern.
Thus, the mask means (or aperture therein) is used to control the deposition of laser beam energy onto the material in any pattern.
Preferably said mask means includes a variable mask, having a transparent or transmitting aperture of variable area for admitting or transmitting said beam.
Preferably the beam spot at the material is initially less than 2.5 mm2, and in one embodiment may initially be less than 1 mm2.
Preferably said beam spot is increased to greater than 5 mm2, and in one embodiment to greater than 10 mm2.
AMENDED SHEET (Article 341 IIPEA/AL11 i coissossooa.s CA 0 2 2 9 4 5 9 2 19 9 9 - 12 - 15 PCTlAU98/00465 Received 1? August 1999 4a Preferably said laser beam is one of a plurality of laser beams.
Preferably said mask means includes an iris diaphragm.
The iris diaphragm may have a central hole with a variable diameter for producing beam spots on said tissue from less than 0.5 mm to 10 mm in diameter.
In one embodiment, the central hole has a variable diameter for producing beam spots on said tissue between 0.5 mm and 6 mm in diameter.
After said iris the beam may go through optics to minify or magnify said beam AMENDED SHEET (Article 34) (IPEA/AUl coisso3sooa.s CA 0 2 2 9 4 5 9 2 19 9 9 - 12 - 15 _ ~ . ' ~ PCT/AU98/00465 Received 09 March 1999 size.
In one preferred embodiment, said beam is scanned over said tissue in a plurality of patterns sequentially, and in another preferred embodiment said pattern may be changed during a procedure.
wherein said mask means is varied to increase said predetermined cross-section as the incident beam is scanned;
and wherein said predetermined pattern includes multiple selected paths on and around said material, in each of which there are a plurality of pulses of said incident beam;
said apparatus further including computer means coupled to or incorporated in said scanning unit and to said mask means for jointly controlling both, said computer means having an installed program for effecting said predetermined scanning pattern and for varying said mask means to progressively increase said predetermined cross-section during said scanning in said predetermined pattern.
Thus, the mask means (or aperture therein) is used to control the deposition of laser beam energy onto the material in any pattern.
Preferably said mask means includes a variable mask, having a transparent or transmitting aperture of variable area for admitting or transmitting said beam.
Preferably the beam spot at the material is initially less than 2.5 mm2, and in one embodiment may initially be less than 1 mm2.
Preferably said beam spot is increased to greater than 5 mm2, and in one embodiment to greater than 10 mm2.
AMENDED SHEET (Article 341 IIPEA/AL11 i coissossooa.s CA 0 2 2 9 4 5 9 2 19 9 9 - 12 - 15 PCTlAU98/00465 Received 1? August 1999 4a Preferably said laser beam is one of a plurality of laser beams.
Preferably said mask means includes an iris diaphragm.
The iris diaphragm may have a central hole with a variable diameter for producing beam spots on said tissue from less than 0.5 mm to 10 mm in diameter.
In one embodiment, the central hole has a variable diameter for producing beam spots on said tissue between 0.5 mm and 6 mm in diameter.
After said iris the beam may go through optics to minify or magnify said beam AMENDED SHEET (Article 34) (IPEA/AUl coisso3sooa.s CA 0 2 2 9 4 5 9 2 19 9 9 - 12 - 15 _ ~ . ' ~ PCT/AU98/00465 Received 09 March 1999 size.
In one preferred embodiment, said beam is scanned over said tissue in a plurality of patterns sequentially, and in another preferred embodiment said pattern may be changed during a procedure.
5 In a particularly useful application, the material to be ablated is human or animal tissue, eg. corneal tissue.
Preferably said method and apparatus are used to fully or partially correct defects in eyesight.
The iris diaphragm may have a central hole with a variable diameter for producing beam spot sizes on said tissue from less than 0.5 mm to 10 mm in diameter.
In one embodiment, the central hole has a variable diameter for producing beam spot sizes on said tissue between 0.5 mm and 6 mm in diameter.
In all of the above aspects of the invention, the laser source or source of the laser beam is preferably an Argon-Fluoride excimer laser (193 nm), flash-lamp or laser pumped solid state laser (193 - 215 nm) such as quintupled Nd-YAG laser or a quadrupled Ti:Sapphire laser, Ho:YAG (2.1 micrometres), Er:YAG or Er:glass laser or tunable IR laser.
Preferred embodiments of the invention will be described, by way of example with reference to the accompanying drawing, in which:
Figure 1 is a schematic view of an apparatus according to the present invention.
An apparatus for laser ablation is shown generally in Figure 1. The apparatus includes a laser source 1. This laser source produces a laser beam 2 which passes through beam smoothing components 3 before continuing through to a variable mask in the form of an iris diaphragm 4. The beam is then directed AMENDED SHEET (Article 34) (IPEA/AU) c ~~sso3sooa.s CA 0 2 2 9 4 5 9 2 19 9 9 - 12 - 15 . ' ~ PCT/AU98/00465 Received 09 March 1999
Preferably said method and apparatus are used to fully or partially correct defects in eyesight.
The iris diaphragm may have a central hole with a variable diameter for producing beam spot sizes on said tissue from less than 0.5 mm to 10 mm in diameter.
In one embodiment, the central hole has a variable diameter for producing beam spot sizes on said tissue between 0.5 mm and 6 mm in diameter.
In all of the above aspects of the invention, the laser source or source of the laser beam is preferably an Argon-Fluoride excimer laser (193 nm), flash-lamp or laser pumped solid state laser (193 - 215 nm) such as quintupled Nd-YAG laser or a quadrupled Ti:Sapphire laser, Ho:YAG (2.1 micrometres), Er:YAG or Er:glass laser or tunable IR laser.
Preferred embodiments of the invention will be described, by way of example with reference to the accompanying drawing, in which:
Figure 1 is a schematic view of an apparatus according to the present invention.
An apparatus for laser ablation is shown generally in Figure 1. The apparatus includes a laser source 1. This laser source produces a laser beam 2 which passes through beam smoothing components 3 before continuing through to a variable mask in the form of an iris diaphragm 4. The beam is then directed AMENDED SHEET (Article 34) (IPEA/AU) c ~~sso3sooa.s CA 0 2 2 9 4 5 9 2 19 9 9 - 12 - 15 . ' ~ PCT/AU98/00465 Received 09 March 1999
6 toward the scanning unit 5, before passing to the surface of the cornea 7. A
computer 6 controls the operation of both the mask and the scanning device.
In use the computer 6 controls iris diaphragm 4. In the preferred method of operation, the iris 4 is used to vary the beam diameter - in steps - during a surgical procedure, initially being set to a small iris diameter and hence beam size (with a beam spot diameter of generally between 0.1 mm and 2.5 mm) and increasing to a larger iris setting (to produce a beam spot diameter of between 2.5 mm and 6 mm).
As the beam size is progressively increased, a number of pulses of each desired size, scanned in the selected pattern or path, are applied to the cornea:
1 ) For spherical corrections, the laser pulses are preferably evenly spaced around a circular path. Each circular path has at least 5 pulses, but more than one circular path may be traced out at each beam size step;
2) For astigmatic corrections, the distribution around the path may be more concentrated in one axis than in another and/or the paths may be made elliptical;
3) For irregular astigmatism corrections, the scanning path will be irregular, the spacing between pules will be irregular and there may be only 1 pulse per beam size.
Where there are more than 5 pulses in a circular path, the pulses are applied in an order such that the scanner transverses the path (be it circular, elliptical or irregular) in no more than about 0.5 s and will continue going around the path until all pulses are fired. Thus, for example, if there are ten pulses to be fired at 10 Hz, every second position is hit on the first pass around the path, and the intermediate positions are hit on the next pass of the laser beam around that path.
When the required treated size is larger than the maximum beam size and/or the desired shape cannot be created using an iris alone, the varying sized beam is AMENDED SHEET (Article 341 (IPEA/AU) i coissossooa.s CA 0 2 2 9 4 5 9 2 19 9 9 - 12 - 15 ' ~ ' ' PCT/AU98/00465 Received 09 March 1999
computer 6 controls the operation of both the mask and the scanning device.
In use the computer 6 controls iris diaphragm 4. In the preferred method of operation, the iris 4 is used to vary the beam diameter - in steps - during a surgical procedure, initially being set to a small iris diameter and hence beam size (with a beam spot diameter of generally between 0.1 mm and 2.5 mm) and increasing to a larger iris setting (to produce a beam spot diameter of between 2.5 mm and 6 mm).
As the beam size is progressively increased, a number of pulses of each desired size, scanned in the selected pattern or path, are applied to the cornea:
1 ) For spherical corrections, the laser pulses are preferably evenly spaced around a circular path. Each circular path has at least 5 pulses, but more than one circular path may be traced out at each beam size step;
2) For astigmatic corrections, the distribution around the path may be more concentrated in one axis than in another and/or the paths may be made elliptical;
3) For irregular astigmatism corrections, the scanning path will be irregular, the spacing between pules will be irregular and there may be only 1 pulse per beam size.
Where there are more than 5 pulses in a circular path, the pulses are applied in an order such that the scanner transverses the path (be it circular, elliptical or irregular) in no more than about 0.5 s and will continue going around the path until all pulses are fired. Thus, for example, if there are ten pulses to be fired at 10 Hz, every second position is hit on the first pass around the path, and the intermediate positions are hit on the next pass of the laser beam around that path.
When the required treated size is larger than the maximum beam size and/or the desired shape cannot be created using an iris alone, the varying sized beam is AMENDED SHEET (Article 341 (IPEA/AU) i coissossooa.s CA 0 2 2 9 4 5 9 2 19 9 9 - 12 - 15 ' ~ ' ' PCT/AU98/00465 Received 09 March 1999
7 scanned in an appropriate pattern to produce the desired shape. The beam control may be optimized such that is always scans the largest beam possible so that the treatment time is minimized and the tissue hydration is maintained as uniformly as possible.
The apparatus of the present invention therefore provides for accurate ablation, providing an alternative beam control method, while maintaining the advantages associated with two prior methods of laser ablation.
Modifications within the spirit and scope of the invention may readily be effected by person skilled in the art. it is to be understood, therefore, that this invention is not limited to the particular embodiments described by way of example hereinabove.
AMENDED SHEET (Article 341 (IPEA/AUl WO 98/57604 PCTlAU98/00465 _ g _ and 2.5 mm) and increasing to a larger iris setting (to produce a beam spot diameter of between 2.5 mm and 6 mm).
As the beam size is progressively increased, a number of pulses of each desired size, scanned in the selected pattern or path, are applied to the cornea:
1) For spherical corrections, the laser pulses are preferably evenly spaced around a circular path. Each circular path has at least 5 pulses, but more than one circular path may be traced out at each beam size step;
2) For astigmatic corrections, the distribution around the path may be more concentrated in one axis than in another and/or the paths may be made elliptical;
3) For irregular astigmatism corrections, the scanning path will be irregular, the spacing between pulses will be irregular and there may be only 1 pulse per beam size.
Where there are more than 5 pulses in a circular path, the pulses are applied in an order such that the scanner transverses the path (be it circular, elliptical or irregular) in no more than about 0.5 s and will continue going around the path until all pulses are fired. Thus, for example, if there are ten pulses to be fired at 10 Hz, every second position is hit on the first pass around the path, and the intermediate positions are hit on the next pass of the laser beam around that path.
When the required treated size is larger than the maximum beam size and/or the desired shape cannot be created using an iris aloae, the varying sized beam is scanned in an appropriate pattern to produce the desired shape. The beam control may be optimized such that it always scans the largest beam possible so that the treatment time is minimized and the tissue hydration is maintained as uniformly as possible.
_ g _ The apparatus of the present invention therefore provides for accurate ablation, providing an alternative beam control method, while maintaining the advantages associated with two prior methods of laser ablation.
Modifications within the spirit and scope of the invention may readily be effected by person skilled in the art. It is to be understood, therefore, that this invention is not limited to the particular embodiments described by way of example hereinabove.
The apparatus of the present invention therefore provides for accurate ablation, providing an alternative beam control method, while maintaining the advantages associated with two prior methods of laser ablation.
Modifications within the spirit and scope of the invention may readily be effected by person skilled in the art. it is to be understood, therefore, that this invention is not limited to the particular embodiments described by way of example hereinabove.
AMENDED SHEET (Article 341 (IPEA/AUl WO 98/57604 PCTlAU98/00465 _ g _ and 2.5 mm) and increasing to a larger iris setting (to produce a beam spot diameter of between 2.5 mm and 6 mm).
As the beam size is progressively increased, a number of pulses of each desired size, scanned in the selected pattern or path, are applied to the cornea:
1) For spherical corrections, the laser pulses are preferably evenly spaced around a circular path. Each circular path has at least 5 pulses, but more than one circular path may be traced out at each beam size step;
2) For astigmatic corrections, the distribution around the path may be more concentrated in one axis than in another and/or the paths may be made elliptical;
3) For irregular astigmatism corrections, the scanning path will be irregular, the spacing between pulses will be irregular and there may be only 1 pulse per beam size.
Where there are more than 5 pulses in a circular path, the pulses are applied in an order such that the scanner transverses the path (be it circular, elliptical or irregular) in no more than about 0.5 s and will continue going around the path until all pulses are fired. Thus, for example, if there are ten pulses to be fired at 10 Hz, every second position is hit on the first pass around the path, and the intermediate positions are hit on the next pass of the laser beam around that path.
When the required treated size is larger than the maximum beam size and/or the desired shape cannot be created using an iris aloae, the varying sized beam is scanned in an appropriate pattern to produce the desired shape. The beam control may be optimized such that it always scans the largest beam possible so that the treatment time is minimized and the tissue hydration is maintained as uniformly as possible.
_ g _ The apparatus of the present invention therefore provides for accurate ablation, providing an alternative beam control method, while maintaining the advantages associated with two prior methods of laser ablation.
Modifications within the spirit and scope of the invention may readily be effected by person skilled in the art. It is to be understood, therefore, that this invention is not limited to the particular embodiments described by way of example hereinabove.
Claims (71)
1. A method for ablating material, including:
directing a pulsed laser beam through variable mask means to produce an incident beam of cross-section predetermined by the mask means; and scanning the incident beam in a predetermined pattern onto the material to thereby ablate the material;
wherein said predetermined cross-section is progressively increased by said mask means during said scanning in said predetermined pattern;
and wherein said predetermined pattern includes multiple selected paths on and around said material, in each of which there are a plurality of pulses of said incident beam.
directing a pulsed laser beam through variable mask means to produce an incident beam of cross-section predetermined by the mask means; and scanning the incident beam in a predetermined pattern onto the material to thereby ablate the material;
wherein said predetermined cross-section is progressively increased by said mask means during said scanning in said predetermined pattern;
and wherein said predetermined pattern includes multiple selected paths on and around said material, in each of which there are a plurality of pulses of said incident beam.
2. A method for ablating material as claimed in claim 1, wherein said mask means includes a variable mask, having a transparent or transmitting aperture of variable area for admitting or transmitting said beam.
3. A method according to claim 1 or 2 wherein said predetermined cross-section is increased in successive steps as the incident beam is scanned.
4. A method according to claim 3 wherein there are a plurality of pulses of said incident beam at each of said steps in said predetermined cross-section.
5. A method according to any one of claims 1 to 4 wherein said pattern and said mask means are arranged so that said cross-section produces a beam spot at said material of a diameter which is increased during said scanning from between 0.1 and 2.5 mm to between 2.5 and 6 mm.
6. A method for ablating material as claimed in any one of claims 1 to 4, wherein said mask means is arranged so that said cross-section produces a beam spot at said material which is initially less than 5 mm2.
7. A method for ablating material as claimed in claim 5 or 6 wherein said mask means is arranged so that said cross-section produces a beam spot at said material which is initially less than 1 mm2.
8. A method for ablating material as claimed in any one of claims 1 to 4, wherein said mask means is arranged so that said cross-section produces a beam spot at said material which is increased during said scanning to greater than 5 mm2.
9. A method for ablating material as claimed in claim 8, wherein said beam spot is increased to greater than 10 mm2.
10. A method for ablating material as claimed in any one of the preceding claims, wherein said laser beam is generated by an Argon-Fluoride excimer laser, flash-lamp or laser pumped solid state laser.
11. A method for ablating material as claimed in any one of claims 1 to 9, wherein said laser beam is generated by a quintupled Nd:YAG laser, a quadrupled Ti:Sapphire laser, a Ho:YAG, Er:YAG or Er:glass laser, or a tunable IR laser.
12. A method for ablating material as claimed in any one of the preceding claims, wherein said laser beam is one of a plurality of laser beams.
13. A method for ablating material as claimed in any one of the preceding claims, wherein said mask means is computer controlled.
14. A method for ablating material as claimed in any one of the preceding claims, wherein said mask means includes an iris diaphragm.
15. A method for ablating material as claimed in claim 14, wherein said iris diaphragm has a central hole with a variable diameter for producing beam spots on said material from less than 0.5 mm to 10 mm in diameter.
16. A method for ablating material as claimed in claim 15, wherein said iris diaphragm has a central hole with a variable diameter for producing beam spots on said material of between 0.5 mm and 6 mm in diameter.
17. A method for ablating material as claimed in any one of the preceding claims, including passing said beam through minifying or magnifying optics to minify or magnify the size of said beam, after said beam has passed through said mask means.
18. A method for ablating material as claimed in any one of the preceding claims, including changing said pattern during a procedure.
19. A method for ablating material as claimed in any one of the preceding claims, wherein said pattern is one of a plurality of patterns.
20. An apparatus for laser ablation of material including:
a laser source for producing a pulsed laser beam;
variable mask means;
means for directing said beam through said mask means to produce an incident beam of cross-section predetermined by the mask means; and a computer-controllable scanning unit for scanning said incident beam in a predetermined pattern onto said material to thereby ablate the material;
wherein said mask means is varied to increase said predetermined cross-section as the incident beam is scanned;
and wherein said predetermined pattern includes multiple selected paths on and around said material, in each of which there are a plurality of pulses of said incident beam;
said apparatus further including computer means coupled to or incorporated in said scanning unit and to said mask means for jointly controlling both, said computer means having an installed program for effecting said predetermined scanning pattern and for varying said mask means to progressively increase said predetermined cross-section during said scanning in said predetermined pattern.
a laser source for producing a pulsed laser beam;
variable mask means;
means for directing said beam through said mask means to produce an incident beam of cross-section predetermined by the mask means; and a computer-controllable scanning unit for scanning said incident beam in a predetermined pattern onto said material to thereby ablate the material;
wherein said mask means is varied to increase said predetermined cross-section as the incident beam is scanned;
and wherein said predetermined pattern includes multiple selected paths on and around said material, in each of which there are a plurality of pulses of said incident beam;
said apparatus further including computer means coupled to or incorporated in said scanning unit and to said mask means for jointly controlling both, said computer means having an installed program for effecting said predetermined scanning pattern and for varying said mask means to progressively increase said predetermined cross-section during said scanning in said predetermined pattern.
21 An apparatus as claimed in claim 20, wherein said mask means includes a variable mask, having a transparent or transmitting aperture of variable area for admitting or transmitting said beam.
22. An apparatus as claimed in claim 21, wherein said area is variable from less than 5 mm2.
23. An apparatus as claimed in claim 22, wherein said area is variable to less than 1 mm2.
24. An apparatus as claimed in any one of claims 21 to 23, wherein said area is variable to greater than 5 mm2.
25. An apparatus as claimed in claim 24, wherein said area is variable to greater than 10 mm2.
26. An apparatus as claimed in any one of claims 20 to 25, wherein said laser source is an Argon-Fluoride excimer laser, flash-lamp or laser pumped solid state laser.
27. An apparatus as claimed in any one of claims 20 to 25, wherein said laser source is a quintupled Nd:YAG laser, a quadrupled Ti:Sapphire laser, a Ho:YAG, Er:YAG or Er:glass laser, or a tunable IR laser.
28. An apparatus as claimed in any one of claims 20 to 27, wherein said laser source is one of a plurality of laser sources.
29. An apparatus as claimed in any one of claims 20 to 28, wherein said mask means includes an iris diaphragm.
30. (Deleted)
31. A method according to any one of claims 1 to 19 wherein said material is human or animal tissue.
32. A method as claimed in claim 31, wherein said tissue is corneal.
33. A method as claimed in either claim 31 or 32, wherein said method is used to fully or partially correct defects in eyesight.
34. (Cancelled)
35. (Cancelled)
36. (Cancelled)
37. (Cancelled)
38. (Cancelled)
39. (Cancelled)
40. (Cancelled)
41. (Cancelled)
42. (Cancelled)
43. (Cancelled)
44. (Cancelled)
45. A method as claimed in claim 31, 32 or 33 including depositing on said tissue a series of evenly spaced pulses of said incident beam around said pattern, wherein said pattern is circular, for spherical correction of corneal tissue.
46. A method as claimed in claim 45, wherein said series includes at least 5 pulses.
47. A method as claimed in claim 31, 32 or 33 including depositing on said tissue a series of pulses of said incident beam around said pattern, wherein said pattern is elliptical and/or said pulses are more concentrated in one portion of said pattern, for astigmatic correction of corneal tissue.
48. A method as claimed in claim 31, 32 or 33 including depositing on said tissue a series of irregularly spaced pulses of said incident beam around said pattern, wherein said pattern is irregular, for irregular astigmatic correction of corneal tissue.
49. A method as claimed in claim 48, including depositing one beam pulse per mask or beam cross-section size.
50. Apparatus according to any one of claims 20 to 30 and 69 to 71 adapted for laser ablation of animal or human tissue, said laser source producing a beam of far ultraviolet or infra-red light.
51. An apparatus as claimed in claim 50, wherein said tissue is corneal.
52. An apparatus as claimed in either claim 50 or 51, wherein said apparatus is adapted for the full or partial correction of defects in eyesight.
53. (Cancelled)
54. (Cancelled)
55. (Cancelled)
56. (Cancelled)
57. (Cancelled)
58. (Cancelled)
59. (Cancelled)
60. (Cancelled)
61. An apparatus as claimed in any one of claims 50 to 52, including minifying or magnifying optics located after said mask, wherein said beam may be minified or magnified in size by being passed through said optics.
62. An apparatus as claimed in any one of claims 50 to 52 and 61, including means for changing said pattern during a procedure.
63. An apparatus as claimed in any one of claims 50 to 52, 61 and 62, wherein said pattern is circular and said computer means is programmed to control said beam to be directed in a series of evenly spaced pulses around said pattern for spherical correction of corneal tissue.
64. An apparatus as claimed in claim 63, wherein said series includes at least pulses.
65. 4n apparatus as claimed in any one of claims 50 to 52, and 61 and 62, wherein said computer means is programmed to control said beam to be directed in a series of pulses around said pattern, and said pattern is elliptical and/or said pulses are more concentrated in one portion of said pattern, for astigmatic correction of corneal tissue.
66. An apparatus as claimed in any one of claims 50 to 52, 61 and 62, wherein said computer means is programmed to control said beam to be directed in a series of irregularly spaced pulses around said pattern, and said pattern is irregular, for irregular astigmatic correction of corneal tissue.
67. An apparatus as claimed in claim 66, wherein said computer means is programmed to control said beam to direct one beam pulse per mask or beam size.
68. An apparatus as claimed in any one of claims 50 to 52 and 61 to 67, wherein said pattern is one of a plurality of patterns.
69. An apparatus according to any one of claims 20 to 29, 50 to 52 and 61 to 68, wherein said program is arranged for increasing said predetermined cross-section in successive steps as the incident beam is scanned.
70. An apparatus according to claim 69 wherein said program is arranges whereby there are a plurality of pulses of said incident beam at each of said steps in said predetermined cross-section.
71. An apparatus according to any one of claims 20 to 30, 50 to 52, 69 and 70 wherein said program and said mask means are arranged so that said cross-section produces a beam spot at said material of a diameter which is increased during said scanning from between 0.1 and 2.5 mm to between 2.5 and 6 mm.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AUPO7367A AUPO736797A0 (en) | 1997-06-16 | 1997-06-16 | Large beam scanning laser ablation |
| AUPO7367 | 1997-06-16 | ||
| PCT/AU1998/000465 WO1998057604A1 (en) | 1997-06-16 | 1998-06-16 | Large beam scanning laser ablation |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2294592A1 true CA2294592A1 (en) | 1998-12-23 |
Family
ID=3801659
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002294592A Abandoned CA2294592A1 (en) | 1997-06-16 | 1998-06-16 | Large beam scanning laser ablation |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0989835A4 (en) |
| AU (1) | AUPO736797A0 (en) |
| CA (1) | CA2294592A1 (en) |
| WO (1) | WO1998057604A1 (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6080959A (en) * | 1999-03-12 | 2000-06-27 | Lexmark International, Inc. | System and method for feature compensation of an ablated inkjet nozzle plate |
| US6436093B1 (en) | 2000-06-21 | 2002-08-20 | Luis Antonio Ruiz | Controllable liquid crystal matrix mask particularly suited for performing ophthamological surgery, a laser system with said mask and a method of using the same |
| US6464692B1 (en) | 2000-06-21 | 2002-10-15 | Luis Antonio Ruiz | Controllable electro-optical patternable mask, system with said mask and method of using the same |
| AUPR463201A0 (en) | 2001-04-27 | 2001-05-24 | Q-Vis Limited | Optical beam delivery configuration |
| US10959839B2 (en) | 2013-10-08 | 2021-03-30 | Edwards Lifesciences Corporation | Method for directing cellular migration patterns on a biological tissue |
Family Cites Families (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2576780B1 (en) * | 1985-02-04 | 1991-06-14 | Azema Alain | APPARATUS FOR CHANGING THE CURVATURE OF THE EYE CORNEA OVER THE WHOLE PUPILLARY SURFACE BY PHOTOCHEMICAL ABLATION OF THE SAME |
| AU606315B2 (en) | 1985-09-12 | 1991-02-07 | Summit Technology, Inc. | Surface erosion using lasers |
| US5284477A (en) * | 1987-06-25 | 1994-02-08 | International Business Machines Corporation | Device for correcting the shape of an object by laser treatment |
| US5159172A (en) * | 1990-08-07 | 1992-10-27 | International Business Machines Corporation | Optical projection system |
| US5637109A (en) * | 1992-02-14 | 1997-06-10 | Nidek Co., Ltd. | Apparatus for operation on a cornea using laser-beam |
| DE4232915A1 (en) * | 1992-10-01 | 1994-04-07 | Hohla Kristian | Device for shaping the cornea by removing tissue |
| US5520679A (en) * | 1992-12-03 | 1996-05-28 | Lasersight, Inc. | Ophthalmic surgery method using non-contact scanning laser |
| US5634919A (en) * | 1993-02-22 | 1997-06-03 | The Johns Hopkins University | Correction of strabismus by laser-sculpturing of the cornea |
| CO4230054A1 (en) | 1993-05-07 | 1995-10-19 | Visx Inc | METHOD AND SYSTEMS FOR LASER TREATMENT OF REFRACTIVE ERRORS USING TRAVELING IMAGES FORMATION |
| WO1995027534A1 (en) * | 1994-04-08 | 1995-10-19 | Summit Technology, Inc. | Control of photorefractive keratectomy |
-
1997
- 1997-06-16 AU AUPO7367A patent/AUPO736797A0/en not_active Abandoned
-
1998
- 1998-06-16 WO PCT/AU1998/000465 patent/WO1998057604A1/en not_active Application Discontinuation
- 1998-06-16 EP EP98929122A patent/EP0989835A4/en not_active Withdrawn
- 1998-06-16 CA CA002294592A patent/CA2294592A1/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| AUPO736797A0 (en) | 1997-07-10 |
| WO1998057604A1 (en) | 1998-12-23 |
| EP0989835A4 (en) | 2003-03-26 |
| EP0989835A1 (en) | 2000-04-05 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Discontinued |