Classifications

• • 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
• • 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
• • 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

Definitions

• 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) .
• PRK photorefractive keratectomy
• LASIK laser in-situ keratomileusis
• 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 is 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 Al and in Ophthalmic Excimer Lasers : Principles and Practice, edited by McGee, C, Taylor, H.R., Gartry, D., Trokel, S., Martin Dunitz Limited, London (1997) when, for example, hyperopia is being corrected.
• 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.
• a method for ablating material including directing a laser beam through a mask and through a scanning unit to an area of said material to thereby ablate said material, wherein said scanning unit can scan or be controlled to scan the beam in a predetermined pattern on said material.
• the mask (or aperture therein) is used to control the deposition of laser beam energy onto the material in any pattern.
• said mask is a variable mask, having a transparent or transmitting aperture of variable area for admitting or transmitting said beam.
• Preferably said method includes varying said area.
• Preferably said method includes increasing said area during a procedure.
• said area is initially less than 2.5 mm 2 , and in one embodiment may initially be less than 1 mm 2 .
• said area is increased to greater than 5 mm 2 , and in one embodiment to greater than 10 mm 2 .
• said laser beam is one of a plurality of laser beams.
• said mask is computer controlled.
• said mask is an iris diaphragm.
• the iris diaphragm may have a central hole with a variable diameter for producing beam sizes on said tissue from less than 0.5 mm to 10 mm in diameter.
• the central hole has a variable diameter for producing beam sizes on said tissue between 0.5 mm and 6 mm in diameter.
• the beam may go through optics to minify or magnify said beam size.
• 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.
• the present invention also provides 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 said beam through said mask, and a computer-controlled scanning unit for scanning or being controlled to scan the beam in a predetermined pattern on said material, wherein said beam is directed to an area of the material to be ablated.
• said mask is a variable mask, having a transparent or transmitting aperture of variable area for admitting or transmitting said beam.
• said area is variable from less than 5 mm 2 , and in another embodiment from less than 1 mm 2 .
• the area may be variable to greater than 5 mm 2 , and in one embodiment to greater than 10 mm 2 .
• said laser source is one of a plurality of laser sources .
• said mask is an iris diaphragm.
• said mask is a computer controlled iris diaphragm.
• a method for ablating human or animal tissue including directing a laser beam through a mask and through a scanning unit to an area of said tissue to thereby ablate said tissue, wherein said scanning unit can scan or be controlled to scan the beam in a predetermined pattern on said tissue.
• said tissue is corneal.
• Preferably said method is used to fully or partially correct defects in eyesight.
• said mask is a variable mask.
• said laser beam is one of a plurality of laser beams.
• said mask is computer controlled.
• said mask is an iris diaphragm.
• the iris diaphragm may have a central hole with a variable diameter for producing beam sizes on said tissue from less than 0.5 mm to 10 mm in diameter.
• the central hole has a variable diameter for producing beam sizes on said tissue between 0.5 mm and 6 mm in diameter.
• Preferably said method includes varying said diameter during a procedure.
• an apparatus for laser ablation of animal or human tissue including a laser source for producing a beam of far ultra-violet or infra-red light, a mask, means for directing said beam through said mask, and a computer-controlled scanning unit for scanning or being controlled to scan the beam in a predetermined pattern on said tissue, wherein said beam is directed to an area of said tissue to be ablated.
• said tissue is corneal.
• said apparatus is adapted for the full or partial correction of defects in eyesight.
• said mask is a variable mask.
• said laser source is one of a plurality of laser sources .
• said mask is computer controlled.
• said mask is an iris diaphragm.
• the iris diaphragm may have a central hole with a variable diameter for producing beam sizes on said tissue from less than 0.5 mm to 10 mm in diameter.
• the central hole has a variable diameter for producing beam sizes on said tissue between 0.5 mm and 6 mm in diameter.
• the laser source or source of the laser beam is preferably a large or compact 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.
• a large or compact 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.
• Figure 1 is a schematic view of an apparatus according to the present invention.
• 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 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.
• the computer 6 controls iris diaphragm 4.
• 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) .
• 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;
• the distribution around the path may be more concentrated in one axis than in another and/or the paths may be made elliptical;
• the scanning path will be irregular, the spacing between pulses will be irregular and there may be only 1 pulse per beam size.
• 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.
• 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.
• 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.
• 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.
• 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.

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• Health & Medical Sciences (AREA)
• Optics & Photonics (AREA)
• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Ophthalmology & Optometry (AREA)
• Heart & Thoracic Surgery (AREA)
• Surgery (AREA)
• Biomedical Technology (AREA)
• Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
• Vascular Medicine (AREA)
• Life Sciences & Earth Sciences (AREA)
• Animal Behavior & Ethology (AREA)
• General Health & Medical Sciences (AREA)
• Public Health (AREA)
• Veterinary Medicine (AREA)
• Plasma & Fusion (AREA)
• Mechanical Engineering (AREA)
• Laser Beam Processing (AREA)

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• 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 CA CA002294592A patent/CA2294592A1/en not_active Abandoned
  • 1998-06-16 EP EP98929122A patent/EP0989835A4/de not_active Withdrawn

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