EP1051118A1 - Technique et appareil d'ablation par laser a effet lisse et uniforme - Google Patents

Technique et appareil d'ablation par laser a effet lisse et uniforme

Info

Publication number
EP1051118A1
EP1051118A1 EP99902049A EP99902049A EP1051118A1 EP 1051118 A1 EP1051118 A1 EP 1051118A1 EP 99902049 A EP99902049 A EP 99902049A EP 99902049 A EP99902049 A EP 99902049A EP 1051118 A1 EP1051118 A1 EP 1051118A1
Authority
EP
European Patent Office
Prior art keywords
laser beam
ablating
ablation
tissue
scan lines
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP99902049A
Other languages
German (de)
English (en)
Inventor
Fuqian Tang
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
LaserSight Technologies Inc
Original Assignee
LaserSight Technologies Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US09/041,998 external-priority patent/US6132424A/en
Application filed by LaserSight Technologies Inc filed Critical LaserSight Technologies Inc
Publication of EP1051118A1 publication Critical patent/EP1051118A1/fr
Withdrawn legal-status Critical Current

Links

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
    • 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
    • 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
    • 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
    • A61F2009/00897—Scanning mechanisms or algorithms

Definitions

  • This invention relates generally to a method and apparatus for scanning an ablating laser beam to ablate tissue. More particularly, it relates to a method and apparatus for scanning an ablating laser beam to ablate corneal tissue resulting in improved smoothness and uniformity of the remaining tissue.
  • the ablation of human tissue with an ablating laser beam is known.
  • a laser beam is scanned across rows of ablation points in an ablation zone of a layer of tissue to be ablated, and adjacent points or spots in each row are sequentially ablated to reshape the underlying tissue.
  • laser ablation is utilized to reshape a cornea of an eye to correct refractive disorders.
  • the cornea bends or refracts incoming light rays causing light rays to focus on the retina of the eye.
  • Improper refraction of incoming light rays causes blurred vision or a refractive disorder.
  • Myopia nearsightedness
  • the cornea is too steep, causing light rays to be focused in front of the retina, not at the retina, causing distant objects to appear blurred.
  • laser vision correction e.g.,
  • Photorefractive Keratectomy can be performed to make the cornea less steep.
  • an ablating laser beam removes successive layers of corneal tissue from an ablation zone of a cornea. Each layer of comeal tissue is removed by ablating the corneal tissue with a series of adjacent laser beam pulses disposed generally along a linear path (e.g., a row).
  • a linear path e.g., a row
  • Fig. 1 shows a conventional scan pattern across an ablation zone.
  • an ablation layer defined by ablation zone 135, of a patient's eye that ideally remains stationary during an ablation treatment of an ablating laser beam, is scanned with an ablating laser beam across rows 1 to 10, from left to right. If the eye remains stationary, the ablation points are distributed evenly throughout the ablation zone, and the remaining corneal tissue will be relatively smooth and uniform.
  • Fig. 2 shows the same ablation zone 135 as in Fig. 1 , but as resulting when the patient's eye has moved downwardly at the end of the third scanning line 3.
  • the fourth and fifth scanning lines 4, 5 as shown in Fig. 2 are scanned on previously ablated areas of the ablation zone 135 instead of at the proper, or planned location as shown in Fig. 1.
  • the sixth scanning line 6 the patient's eye moves back to the correct or intended position, and proper or intended ablation continues.
  • the corneal surface is ablated too deeply in certain portions thereof (i.e., between the first and third scan lines 1, 3) and is ablated too shallowiy in another portion of the cornea (i.e., between the third and sixth scan lines 3, 6). This results in a rough and/or non-uniform surface on the remaining corneal tissue.
  • the ablation points shown in Fig. 1 and Fig. 2 represent the center of each ablating laser beam pulse. Significant ablation overlap can occur when the ablating laser beam is larger than the distance between each ablation point. However, when the eye moves during corrective eye surgery, the resulting or actual location of the scanned ablation points with respect to the ablation zone 135 is significantly deeper than other properly scanned ablation points, while other portions of the corneal tissue may not have been ablated as intended. This may result in uneven, rough and/or non-smooth ridges on the cornea.
  • An object of the invention is to provide a method of ablating tissue fulfill the need referred to above.
  • this objective is obtained by providing a method of ablating tissue including defining a plurality of scan lines in an ablation zone on the tissue and defining a plurality of laser beam ablation points along each of the scan lines.
  • An ablating laser beam is scanned along a series of non-adjacent scan lines of the plurality of scan lines and tissue is ablated at non-adjacent ones of the laser beam ablation points on each non-adjacent scan line of the series of non-adjacent scan lines.
  • An apparatus for performing the method is also provided.
  • the above objective is obtained by dividing an ablation zone into a plurality of domains. An average depth of ablation in each of the domains is determined. Tissue is ablated by controlling a number of ablating laser beam pulses in each domain in proportion to the average depth of ablation in each domain. An apparatus is disclosed for performing this method.
  • Fig. 1 is a top plan view illustrating a conventional scanning pattern of an ablating laser beam over an ablation zone wherein the patient's eye remains stationary throughout the performance of the ablation through the scanning pattern;
  • Fig. 2 is a top plan view illustrating a conventional resulting pattern of an ablating laser beam over an ablation zone wherein the patient's eye moves during the performance of the ablation through the intended scanning pattern shown in Fig. 1 ;
  • Fig. 3 is a top plan view illustrating the location of ablation points on scan lines in an ablation zone using a scanning technique in accordance with the principles of the present invention;
  • Fig. 4 is a top plan view illustrating the resulting pattern of an ablation zone divided into a predetermined number of domains, and scanned in accordance with the principles of the present invention.
  • Fig. 5 is a schematic illustration of a laser device for ablating tissue provided in accordance with the principles of the present invention.
  • the present invention provides a method and apparatus for performing laser ablation to remove or reshape human tissue, e.g., corneal tissue in a cornea of an eye.
  • human tissue e.g., corneal tissue in a cornea of an eye.
  • the embodiments of the present invention are described with reference to the removal of corneal tissue, the present invention relates to laser ablation techniques of human tissue in general.
  • the method and apparatus of the present invention further relates to use in laser refractive keratectomy (e.g., photorefractive keratectomy or PRK, PRK after radial keratomy, laser keratectomy with microkeratome, - intrastromal photodisruption), laser therapeutic keratectomy, and/or laser lamellar resection.
  • laser refractive keratectomy e.g., photorefractive keratectomy or PRK, PRK after radial keratomy, laser keratectomy with microkeratome, - intrastromal photodisruption
  • laser therapeutic keratectomy e.g., laser lamellar resection.
  • the method and apparatus of the present invention when applied to vision correction, provides several techniques to achieve smoother and more uniform ablation than is currently known, especially if the patient's eye moves during the vision correction surgery.
  • the present invention scans a laser beam across an ablation zone 135 on a cornea of an eye in a predetermined scan pattern selected in accordance with the desired ablation rate.
  • the present invention provides for intermittent multiple passes along nonadjacent scan lines through the ablation zone 135.
  • the term "intermittent" herein refers to non-adjacent ablation points or spots along a single linear scan or pass through the ablation zone 135.
  • the present invention provides for non-sequential ablation of ablation points along a predetermined scanning pattern.
  • subsequent pass(es) along the same scan lines are performed to cause ablation at non-adjacent ablation points, e.g., between those points already ablated in a previous pass through the scan line through the ablation zone 135.
  • the intermittent nature of the ablation i.e., ablating every other, every third, every fourth, etc., ablation point in any one pass through a scan line of the ablation zone, and/or ablating every other, every third, every fourth, etc., scan line, results in a smooth and uniform tissue surface remaining after the ablation procedure, even in the face of eye movement, as compared to conventional methods and scan patterns.
  • Fig. 3 shows intermittent ablation of a predetermined scanning pattern in accordance with the principles of the present invention.
  • the present invention includes linear scanning patterns on an ablation zone of a cornea.
  • the temporal order of the ablation points is changed to achieve a smoother and more uniform reshaping of the cornea surface, even when the patient's eye moves during the ablation procedure.
  • Fig. 3 illustrates a scanning pattern consisting of twelve (12) scan lines 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, and 44.
  • a linear overlapping intermittent ablation pattern performed in accordance with one embodiment of the present invention, only one-fourth (1/4) of the ablation points in a single layer are ablated during a first pass through the scan lines of the ablation zone 135.
  • An arbitrary starting point is selected and a first series of scan lines in the ablation zone 135 are selected for ablation.
  • a first series of non-adjacent scan lines may be selected to include scan lines 22, 26, 30, 34, 38 and 40.
  • non-adjacent scan lines means scan lines that are not directly adjacent, e.g., scan lines 22 and 26 are nonadjacent since at least one scan line 24 is disposed between scan lines 22 and 26.
  • non-adjacent laser beam ablation points 46, 48, in scan line 22 are ablated.
  • nonlaser beam ablation points means laser beam ablation points that are not directly adjacent, e.g., at least one point, e.g., point 49, is disposed between points 46 and 48.
  • non-adjacent laser beam ablation points 50, 52, 54, 56, 58 on scan line 26 are scanned and ablated
  • nonadjacent laser beam ablation points 60, 62, 64, 66, 68 on scan line 30 are scanned and ablated, etc. until one-fourth of the overall ablation layer in the ablation zone 135 is scanned.
  • the next one-quarter (1/4) of the first layer is scanned and non-adjacent ablation points not previously ablated on each scan line of the first series of scan lines are ablated.
  • a second series of scan lines are selected which include scan lines 24, 28, 32, 36, 40, and 44. Every other ablation point on each scan line of the second series of scan lines is then ablated. This process is repeated to ablate ablation points not previously ablated on each scan line of the second series to complete the overall ablation of the first layer of the ablation zone 135.
  • subsequent layers of corneal tissue within the ablation zone 135 may be ablated using the above-described procedure of the invention.
  • the end result of the ablation In accordance with the principles of the present invention will result in approximately the same evenness and uniformity as resulting from a conventional ablation method and apparatus. However, if the patient's eye moves during the ablation procedure, which generally occurs, the result of the method of the present invention is a smoother and more uniform reshaping of the cornea.
  • the linear overlapping intermittent ablation method of the present invention can be employed by skipping additional laser beam ablation points, such as scanning and ablating only every third point, skipping two (2) scan lines instead of only skipping one (1 ) scan line, etc.
  • a second aspect of the present invention which provides a smooth and uniform ablation is referred to herein as a random overlapping intermittent ablation. As illustrated in Fig. 3, this embodiment comprises following a certain regular scan line pattern as described above, but with a random order of non-adjacent laser beam ablation points and nonadjacent scan lines.
  • Fig. 5 shows a laser device for ablating tissue provided in accordance with the principles of the present invention.
  • a laser ablation device 100 includes a laser 112 operable to produce a pulsed ablating laser beam 114, which is directed to a scanning device 116.
  • the scanning device 116 is operatively connected to a computer system 118 for control thereby.
  • the computer system 118 can be located within the laser device 100, or external thereto.
  • the laser 112 can also be operatively connected to the computer system 118 for control thereby.
  • the scanning device 116 of the laser device 100 of the present invention is operable to control the scanning of the pulsed ablating laser beam 114 across an ablation zone 135 on the cornea 134 of a patient's eye 136.
  • a scanned laser beam 124 departs the scanning device 116 and is directed to other optics components 126 which may be utilized for shaping the scanned beam 124 in a desired manner.
  • a shaped scanned beam 128 may then be directed to a reflecting mirror 130.
  • a reflected beam 132 is directed from the reflecting mirror 130 onto an ablation zone 135 of a cornea 134 of a patient's eye 136.
  • the various portions of the laser device 100 can be constructed, e.g., in accordance with the laser device described in U.S. Patent No. 5,520,679, the disclosure of which is hereby explicitly incorporated herein by reference.
  • the computer system 118 of the present invention controls the scanning device 116 through a scanning pattern in accordance with the principles of the present invention.
  • the laser device 100 is constructed and arranged to scan an ablation zone 135 and ablate tissue at certain ablation points within the ablation zone 135.
  • the tissue to be ablated is divided into a number of successive layers in the ablation zone 135, each layer typically being ablated individually, one after the next.
  • the laser beam 132 is directed toward the tissue to be ablated, and the laser device 100 is intermittently activated or allowed to pass to produce a predetermined amount of laser beam energy at intermittent ablation points 20, e.g., in a linear scan pattern.
  • all of the laser beam ablation points of the scanning pattern for an entire layer or all of the laser beam ablation points of the scanning pattern for all of the layers can be predetermined in the computer system 118.
  • the computer system 118 of the laser device 100 is controlled to selectively or randomly order the intermittent ablation of laser beam ablation points.
  • a third aspect of the present invention which provides a smooth and uniform ablation is referred to herein as a probability overlapping intermittent ablation. It should be understood that the probability overlapping intermittent ablation technique does not follow a layer concept or a linear or circular scanning method.
  • the probability overlapping intermittent ablation technique directs a certain number of laser pulses to a certain laser beam ablation point on the cornea or other tissue proportional to the depth of ablation required at that laser beam ablation point.
  • the ablation zone 135 of the cornea is divided into small domains 70 such as squares, triangles, hexagons, or other shapes.
  • the depth of ablation at the center of each domain 70 is considered the average depth for that particular domain 70.
  • the total volume V of tissue to be removed for the entire surgery is calculated by the surgeon according to the initial conditions such as the diopter of correction, ablation zone size, the initial radius of curvature of the eye, etc.
  • the tissue volume v each laser beam pulse removes is calculated from either the laser pulse characteristics (energy, beam size, pulse duration, etc.), or from experimental data (ablation on plastic or other calibration material).
  • , or k 1/( d
  • the number of laser beam pulses delivered to each domain 70 is proportional to the average depth of ablation in that domain 70. It is important when utilizing this third aspect that the area of treatment be divided into many domains, with the size of each domain 70 being sufficiently small such that the ablation depth profile will closely and smoothly fit the theoretical profile.
  • a computer can distribute the laser beam pulses to optimize the result.
  • the computer system 118 of the laser device 100 can be programmed to require that no greater than two (2) pulses will hit the same ablation point in any one domain, that the distribution of pulses in each domain is even and uniform, and that the distributions near and at the border lines of the domains are relatively uniform, without more than two (2) pulses hitting any same ablation point.
  • the overall even distribution of laser pulses will result in a smooth and uniformly ablated corneal surface even if the patient's eye moves during surgery.
  • the temporal order of the ablation of the ablation points in the predetermined scanning pattern randomized by the computer system 118 should be calculated before the actual ablation treatment of the cornea begins.
  • the number of scan lines within the ablation zone can be increased or decreased.
  • the ablation pattern can overlap successive layers to be ablated within the ablation zone 135.
  • the laser beam ablation points represent the center point of an ablating laser beam on the surface of the tissue to be ablated.
  • the energy of the laser beam typically extends beyond the bounds of the depicted laser beam ablation points or spots causing areas of ablated tissue to overlap.
  • the overlapping of the ablated tissue and/or the number of laser beam ablation points or spots in the ablation zone can be empirically determined to yield optimum results, i.e., surface smoothness, uniformity, accuracy of reshaping, etc.

Landscapes

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

Abstract

La présente invention concerne un système de distribution de faisceaux laser, utilisant une technique permettant une ablation lisse et uniforme des tissus, notamment pour reconstituer la cornée de l'oeil, même dans des conditions réelles telles qu'un oeil en mouvement. Cette technique consiste à former plusieurs lignes de balayage (22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44) dans une zone d'ablation (135) sur les tissus, et à former une pluralité de points d'ablation par faisceaux laser (46, 48, 49) le long de chaque ligne de balayage. On procède au balayage d'un faisceau laser d'ablation le long d'une série de lignes de balayage non adjacentes (22, 26, 30, 34, 38, 42) faisant partie de la pluralité des lignes de balayage, les tissus étant soumis à une ablation par intermittence au niveau des lignes de balayage non adjacentes des points d'ablation à faisceau laser (46, 48), sur chaque ligne de balayage non adjacente. Dans un autre aspect de l'invention, on divise une zone d'ablation (135) en une pluralité de domaines (70), puis on détermine dans chacun de ces domaines une profondeur moyenne d'ablation. On pratique ensuite l'ablation des tissus en commandant dans chaque domaine (70) un certain nombre d'impulsions de faisceaux laser d'ablation, proportionnellement à la profondeur moyenne d'ablation dans chaque domaine (70).
EP99902049A 1998-01-07 1999-01-06 Technique et appareil d'ablation par laser a effet lisse et uniforme Withdrawn EP1051118A1 (fr)

Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
US7065498P 1998-01-07 1998-01-07
US70654P 1998-01-07
US09/041,998 US6132424A (en) 1998-03-13 1998-03-13 Smooth and uniform laser ablation apparatus and method
PCT/US1999/000119 WO1999034740A1 (fr) 1998-01-07 1999-01-06 Technique et appareil d'ablation par laser a effet lisse et uniforme
US41998 2001-10-25

Publications (1)

Publication Number Publication Date
EP1051118A1 true EP1051118A1 (fr) 2000-11-15

Family

ID=26718772

Family Applications (1)

Application Number Title Priority Date Filing Date
EP99902049A Withdrawn EP1051118A1 (fr) 1998-01-07 1999-01-06 Technique et appareil d'ablation par laser a effet lisse et uniforme

Country Status (3)

Country Link
EP (1) EP1051118A1 (fr)
AU (1) AU2212499A (fr)
WO (1) WO1999034740A1 (fr)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8273115B2 (en) 2007-04-24 2012-09-25 W. L. Gore & Associates, Inc. Side branched endoluminal prostheses and methods of delivery thereof

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4665913A (en) * 1983-11-17 1987-05-19 Lri L.P. Method for ophthalmological surgery
US5336217A (en) * 1986-04-24 1994-08-09 Institut National De La Sante Et De La Recherche Medicale (Insepm) Process for treatment by irradiating an area of a body, and treatment apparatus usable in dermatology for the treatment of cutaneous angio dysplasias
DE4232915A1 (de) * 1992-10-01 1994-04-07 Hohla Kristian Vorrichtung zur Formung der Cornea durch Abtragen von Gewebe
US5520679A (en) 1992-12-03 1996-05-28 Lasersight, Inc. Ophthalmic surgery method using non-contact scanning laser
US5599340A (en) * 1994-12-09 1997-02-04 Simon; Gabriel Laser beam ophthalmological surgery method and apparatus
US5782822A (en) * 1995-10-27 1998-07-21 Ir Vision, Inc. Method and apparatus for removing corneal tissue with infrared laser radiation

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9934740A1 *

Also Published As

Publication number Publication date
WO1999034740A1 (fr) 1999-07-15
WO1999034740A9 (fr) 2000-02-17
AU2212499A (en) 1999-07-26

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