FILE HISTORY
`08/516,581
`
`INVENTORS:
`
`TIBOR JUHASZ
`JOSEF F. BILLE.
`
`TITLE:
`
`INTRASTROMAL PHOTOREFRACTIVE
`KERATECTOMY
`
`APPLICATION
`NO:
`FILED:
`
`08/516,581
`
`17 AUG 1995
`
`COMPILED:
`
`10 OCT 2013
`
`Alcon Research, Ltd.
`Exhibit 1021 - Page 1
`
`

`

`K,
`
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`
`UTILITY
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`
`165
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`"3-*----
`SERIAL NUMBER
`08/516, .581
`
`1
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`1 ii
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`
`'
`
`PATENT DATE
`
`.
`
`.5
`
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`FILING DATE CLASS
`606
`08/17/95
`
`BEST COPY
`
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`GROUP ART UNIT
`
`EXAMINER
`
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`
`TIBOR JUHASZ,
`
`IRVINE, CA
`
`-
`..JOSEF F. BILLE, HEIDELBERG, FED REP
`
`~-
`-
`' GERMAN V
`
`VERIFIED
`
`THIS APPLN
`
`IS A C:IP OF
`
`08/151,726 11/12/9:3
`
`:4 :: FO RE II/P
`VERIFIED
`
`T APFL. I CA T I OI\S
`
`:*: :
`
`FOREIGN FILINGA LICENSE GRANTED 12/1:3/95
`AS
`TOTAL
`STATE OR SHEETS
`0 '"
`~
`Foreign priority claimed
`SHEETS
`STATE OR
`TOTAL
`AS
`O yes D no
`Foreign pdiority claimed
`35 USC 119 condltions met 0 yes 0 no
`FILED COUNTRY DRWGS. CLAIMS
`1 4
`Verfied and Ackdowledged Exaer's nitials
`NEIL K NYDEGGER
`NYDEGGER. AND ASSOCIATES
`4350 LA .JOLLA VILLAGE DRIVE
`SUITE 950
`SAN DIEGO CA 92122
`
`CA
`"44
`
`I
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`ATToRNEY'S
`FILING FEE
`ATTORNEY'S
`FILING FEE
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`DOCKET NO.
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`INDER
`INDEP.
`CLAIMS
`
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`I NTRASTROMAL PHOTOREFRACT I VE KERATECTOMY
`
`U.S. DEPT. OF COMM./PAT. & TM-PTO-436L (Rev.12-94)
`
`V 9
`
`PREPARED FOR ISSUE
`
`: The
`disclosed herein may be restricted. Unauthorized disclosure may be prohibited
`-
`the United States Code Title 35, Sections 122, 181 and 368. Possession outside the U.S.
`° patent & Trademark Office is restricted to authorized employees and contractors only.
`; ,!.. ¢ . . ! .:'"
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`Alcon Research, Ltd.
`Exhibit 1021 - Page 2
`
`

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`Alcon Research, Ltd.
`Exhibit 1021 - Page 3
`
`

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`Alcon Research, Ltd.
`Exhibit 1021 - Page 4
`
`

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`Alcon Research, Ltd.
`Exhibit 1021 - Page 5
`
`

`

`I
`
`BAR CODE LABEL
`
`i t
`II lll llll I llttIIIllll l+lU
`
`U.S. PATENT APPLICATION
`
`SERIAL NUMBER
`
`FILING DATE
`
`CLASS
`
`GROUP ART UNIT
`
`08/516,581
`
`,
`
`08/17/95
`
`606
`
`3309
`
`TIBOR JUHASZ, IRVINE, CA; JOSEF F. BILLE, HEIDELBERG, FED REP GERMANY.
`
`**CONTINUING DATA********************
`THIS APPLN IS A CIP OF
`VERIFIED
`
`08/151,726 11/12/93
`
`**FOREIGN/PCT APPLICATIONS************
`VERIFIED
`
`FOREIGN FILING LICENSE GRANTED 12/13/95
`
`***** SMALL ENTITY *****
`
`STATE OR
`COUNTRY
`
`SHEETS
`DRAWING
`
`TOTAL
`CLAIMS
`
`INDEPENDENT
`CLAIMS
`
`FILING FEE
`RECEIVEO
`
`ATTORNEY DOCKET NO.
`
`CA
`
`1
`
`14
`
`3
`
`$440.00
`
`10813.40.11
`
`NEIL K NYDEGGER
`NYDEGGER AND ASSOCIATES
`S 4350 LA JOLLA VILLAGE DRIVE
`
`°
`
`SUITE 950
`SAN DIEGO CA 92122
`
`INTRASTROMAL PHOTOREFRACTIVE KERATECTOMY
`
`This is to certify that annexed hereto is a true copy from the records of the United States
`Patent and Trademark Office of the application which is identified above.
`By authority of the
`COMMISSIONER OF PATENTS AND TRADEMARKS
`
`Date
`
`Certifying Officer
`
`Alcon Research, Ltd.
`Exhibit 1021 - Page 6
`
`

`

`PATENT APPLICATION SERIAL NO.
`
`08/516521
`
`U.S. DEPARTMENT OF COMMERCE
`PATENT AND TRADEMARK OFFICE
`FEE RECORD SHEET
`
`PTO-1556
`(5/87)
`
`Alcon Research, Ltd.
`Exhibit 1021 - Page 7
`
`

`

`3
`-
`
`1
`
`NYDEGGER & ASSOCIATES
`ATTORNCYS AT LAW
`
`R
`AUG
`7
`1995
`
`K.NYoE
`DE
`
`4350
`
`LA JOLLA VILLAGE DRIVE
`SUITE 950
`SAN DIEGO, CALIFORNIA 92122
`
`8/5 16 5 1
`PATENT
`
`TELEPHONE
`(619) 455-5700
`
`" FACSIMILE
`(619) 535-9810
`
`IN THE UNITED STATES PATENT AND TRADEMARK OFFICE
`
`Honorable Commissioner of Patents
`and Trademarks
`Box Patent Application
`Washington, D. C. 20231
`
`Sir:
`
`Transmitted herewith for filing is the patent application of
`0 TibQ Juhasz and Josef F. Bille for INTRASTROMAL PHOTOREFRACTIVE
`KERATECTOMY comprising twenty-two (22) pages of specification and
`f, claims.
`This application is a continuation-in-part of pending
`prior application serial No. 08/151,726 filed on November 12, 1993.
`
`Enclosed also are:
`
`X
`
`X
`
`X
`
`X
`
`One (1) sheet of drawings.
`
`A Certificate of Mailing by "Express Mail" certifying a
`filing date of August 17, 1995 by use of Express Mail
`Label No. TB 836 966 856 US.
`
`No fees are enclosed.
`
`No Declaration, Power of Attorney and Petition is
`Enclosed.
`
`Please address all future correspondence in connection with
`the above-identified patent application to the attention of the
`undersigned.
`
`Dated this 17th day of August, 1995.
`
`R spectfully submitted,
`
`ER
`NE L K. NYD
`Att rney for Applicant
`Registration No. 30,202
`
`NYDEGGER & ASSOCTATF.
`4350 La Jolla Village Drive
`Suite 950
`San Diego, California 92122
`Telephone: (619) 455-5700
`
`NKN:0817b.neo
`Docket: 10813.40.1
`
`.._
`
`-
`
`Alcon Research, Ltd.
`Exhibit 1021 - Page 8
`
`

`

`0851bs8j
`
`'Express Mail Label No. TB 836 966 856 US
`Docket No. 10813.40.1/NKN
`
`PATENT
`
`UNITED STATES PATENT APPLICATION
`
`of
`
`TIBOR JUHASZ AND JOSEF F. BILLE
`
`for
`
`INTRASTROMAL PHOTOREFRACTIVE KERATECTOMY
`
`Alcon Research, Ltd.
`Exhibit 1021 - Page 9
`
`

`

`08/5165 1
`
`1UG
`17
`995 k
`SDE P
`
`RELATED APPLICATION
`
`This application is a continuation-in-part of
`copending U.S Patent Application Serial No. 08/151,726,
`filed
`11/12/93,
`for
`Intrastromal
`Photorefractive
`5 Keratectomy.
`
`FIELD OF THE INVENTION
`
`The present invention pertains to methods for using
`lasers
`to
`accomplish
`ophthalmic
`surgery.
`More
`particularly, the present invention pertains to methods for
`10 reshaping the cornea of the eye to improve a patient's
`vision. The present invention is particularly, but not
`exclusively, useful as a method for intrastromal
`photorefractive keratectomy (ISPRK).
`
`BACKGROUND OF THE INVENTION
`
`15
`
`It is known that the cornea of an eye can, in certain
`instances, be surgically reshaped to correct and improve
`vision. Where the condition being corrected is myopia, or
`near-sightedness, the cornea is relatively flattened,
`whereas if hyperopia is being corrected, the cornea is
`20 relatively steepened. In either case, as more fully set
`forth below, there are several different types of
`ophthalmic surgical procedures which can be employed for
`this purpose. Although the types of procedures may vary,
`the ultimate object in correcting myopia, for example, is
`25 the same. Namely, the object is to cause the anterior
`surface of the cornea to be flattened, usually by reducing
`the center thickness so that it properly refracts light
`entering the eye for subsequent focussing on the retina of
`the eye.
`The most common surgical operation for reshaping the
`cornea is a procedure known as radial keratotomy. This
`
`30
`
`Alcon Research, Ltd.
`Exhibit 1021 - Page 10
`
`

`

`15
`
`10
`
`procedure, which is used primarily to correct myopia, is
`performed by making a series of radial incisions on the
`surface of the cornea. These incisions extend from the
`outer edge of the cornea toward its center in spoke-like
`5 fashion to weaken selected sections of the cornea. With
`these weakened sections, the fluid pressure of the aqueous
`humor inside the eye will cause the cornea to deform. When
`intended for the myopic correction procedure, the desired
`deformation is a flattening of the cornea to provide proper
`light refraction for improved vision.
`In recent years, the use of cutting tools to make
`incisions into the cornea for vision corrections is
`gradually being replaced or supplemented by the use of new
`Rather than making
`surgical procedures using lasers.
`incisions, laser energy which reshape the cornea do so by
`actually removing corneal tissue. This is accomplished by
`a process which is generally known as photoablation.
`Heretofore, the photoablation of corneal tissue has been
`accomplished primarily by focussing laser energy onto the
`20 exposed anterior surface of the eye. The result which can
`be achieved is dependent on two interrelated factors.
`First, the particular laser system which is employed to
`generate a laser beam will significantly affect how the
`photoablation process can be accomplished. Second, the
`25 method by which the laser energy is manipulated to
`accomplish photoablation will effectively determine the
`efficacy of the procedure.
`For ophthalmic laser systems, several different types
`For example, U.S.
`of laser beams have been suggested.
`30 Patent No. 4,665,913 which issued to L'Esperance, Jr. for
`an invention entitled "Method for Ophthalmological Surgery"
`discloses a corneal reshaping procedure using an excimer
`laser. As another example, U.S. Patent No. 4,907,586 which
`issued to Bille et al. for an invention entitled "Method
`35 for Reshaping the Eye", and which is assigned to the same
`
`_-7----rr
`
`Alcon Research, Ltd.
`Exhibit 1021 - Page 11
`
`

`

`assignee as the present invention, discloses a corneal
`reshaping procedure which uses a pulsed laser beam.
`Although using lasers for the removal of corneal
`tissue from the anterior surface of the cornea is known to
`5 be effective, the removal of tissue from the anterior
`surface requires photoablation of several layers of
`different types of tissues in the cornea. These include
`
`portions of the epithelium, Bowman's membrane and the
`The present invention recognizes that it is
`stroma.
`
`10 preferable to leave the epithelium and Bowman's membrane
`intact, and to limit the tissue removal to only the stroma.
`
`Removal of tissue from the stroma results in the creation
`
`of a specially shaped cavity in the stroma layer of the
`
`cornea. When the cornea deforms in the intended manner,
`
`15 the desired flattening of the cornea results. Further, the
`present
`invention recognizes that internal tissue
`
`photoablation, or more precisely "photodisruption", can be
`effectively accomplished using a pulsed laser energy if the
`
`irradiance of the beam, its focal spot size, and the proper
`20 layering of photo disruption sites are effectively
`controlled.
`It is an object of the present invention to provide a
`method for performing intrastromal photodisruption on the
`
`cornea of an eye using a pulsed laser beam which controls
`25 the irradiance of the laser beam to limit the amount of
`tissue which is subject to photodisruption. Another object
`
`of the present invention is to provide a method for
`
`intrastromal photorefractive keratectomy which controls the
`spot size and spot configuration of the laser beam to
`30 permit
`removal
`of
`stromal
`
`tissue
`
`by
`
`contiguous
`
`Still
`photodisruption at successively adjacent spots.
`another object of the present invention is to provide a
`method for intrastromal photodisruption which removes
`stromal tissue in a predetermined pattern of properly sized
`and shaped layers to attain the desired flattening of the
`cornea. Yet another object of the present invention is to
`
`35
`
`Alcon Research, Ltd.
`Exhibit 1021 - Page 12
`
`

`

`provide a method for intrastromal photodisruption which is
`relatively easy to perform and which is comparatively cost
`effective.
`
`SUMMARY OF THE INVENTION
`
`5
`
`10
`
`In accordance with the present invention, a method for
`performing photodisruption and removal of tissue limited to
`the stroma in the cornea of an eye uses a pulsed laser beam
`which is sequentially focused to individual spots at a
`plurality of points in the stroma. Each focus spot has a
`finite volume, rather than being a single point.
`Photodisruption of stromal tissue occurs at each spot where
`the beam is focused, and the volume of stromal tissue
`disrupted at each spot is approximately equal to the volume
`of the spot. The photodisrupted tissue is absorbed into or
`15 removed from the cornea through well known means.
`The
`spots are arranged in successive spiral patterns to
`photodisrupt and remove a plurality of layers of stromal
`tissue, with the diameters of the layers being properly
`sized to result in the desired diopter correction.
`The physical characteristics of the laser beam, as
`well as the manner of focussing the laser beam, are
`important to the proper performance of the method of the
`present
`invention.
`As
`indicated
`above,
`these
`considerations are interrelated.
`First, insofar as the characteristics of the laser
`beam are concerned, several factors are important. The
`laser beam should have a wavelength that allows the light
`to pass through the cornea without absorption by the
`corneal tissue. Accordingly, the light in the laser beam
`30 will not be absorbed as the beam transits through the
`cornea until it reaches the focal spot. Generally, the
`wavelength should be in the range of 0.3 micrometer ( m) to
`3 m, with a wavelength of 1053 nanometers (nm) being
`preferred. The irradiance of the beam for accomplishment
`
`20
`
`25
`
`Alcon Research, Ltd.
`Exhibit 1021 - Page 13
`
`

`

`of photodisruption of stromal tissue at the focal spot
`should be greater than the threshold for optical breakdown
`of the tissue. The irradiance which will cause optical
`breakdown of stromal tissue is approximately 200 GW/cm 2 .
`5 The irradiance preferably should not be more than ten times
`greater than the threshold for optical breakdown and, in
`any event, not more than one hundred times greater than the
`threshold. Further, the pulse repetition frequency of the
`pulsed laser beam is preferably in the range of
`10 approximately 1 to 10 kHz.
`Second, insofar as the focussing of the laser beam is
`concerned, spot size, spot configuration, and spot pattern
`are all important. The spot size of the focused laser beam
`should be small enough to achieve optical breakdown of
`15 stromal tissue at the focal spot. Typically, this requires
`the spot size to be approximately 10 m in diameter.
`Additionally, it is preferable that the spot configuration
`be as close to spherical as possible. To achieve this
`configuration for the spot it is necessary that the laser
`20 beam be focused from a relatively wide cone angle. For the
`present invention, the cone angle will preferably be in the
`range of 15 ° to 45° .
`Finally, the spots must be arranged
`in a pattern that is optimal for creating a cavity of the
`desired shape. The subsequent deformation of the cavity
`25 results in the ultimate reshaping of the cornea in the
`desired fashion to achieve a desired refractive effect.
`To perform intrastromal photodisruption in accordance
`with the method of the present invention, the laser beam is
`focused at a first selected spot at a starting point in the
`For myopic corrections, the starting point is
`30 stroma.
`preferably on the optical axis of the eye at a location
`behind the epithelium. The laser beam is then activated
`and stromal tissue at the first spot is photodisrupted.
`Importantly, because spot size and configuration and the
`irradiance level of the laser beam are closely controlled
`for the present invention, the volume of stromal tissue
`
`35
`
`5
`
`_ . -- _-._T ... _ _ _.___ ___ __
`
`Alcon Research, Ltd.
`Exhibit 1021 - Page 14
`
`

`

`5
`
`which is photodisrupted and removed at the focal spot is
`carefully controlled. Preferably, this volume is about the
`same as the volume occupied by the focal spot, or typically
`about a 10 m diameter spherical volume.
`Next, the laser beam is focused at a second selected
`spot in the stroma.
`The second spot lies in a plane
`containing the first focal spot, with the plane being
`perpendicular to the optical axis of the eye. It should be
`noted, however, that during photodisruption of the stromal
`10 tissue, a cavitation bubble results which has a diameter
`which is up to about twice the diameter of the focal spot.
`Therefore, the second focal spot is selected at a point in
`the stroma which is substantially adjacent to the
`cavitation bubble resulting from the first focal spot.
`15 Again, the laser beam is activated and stromal tissue at
`the second spot is photodisrupted to add to the volume of
`stromal tissue which had previously been photodisrupted.
`Because of the placement of the second spot relative to the
`cavitation bubble from the first spot, there is some
`20 overlap between the cavitation bubbles at the two spots.
`This process is continued, proceeding from point to point
`along a planar spiral through the stroma, until a 10 m
`thick layer of stromal tissue has been photodisrupted and
`removed.
`The layer of photodisrupted tissue is
`25 perpendicular to the optical axis.
`For effective vision correction of the eye using
`intrastromal photorefractive keratectomy techniques, it is
`preferable that tissue photodisruption be accomplished at
`a plurality of adjacent points in a patterned sequence to
`30 create a plurality of layers of tissue removal. The object
`is to create a dome shaped cavity within the stromal
`tissue.
`The dome shaped cavity subsequently collapses,
`reshaping the corneal surface.
`The present invention
`contemplates that the adjacent focal spots in a given layer
`35 of the stroma are all located in a plane perpendicular to
`the optical axis of the eye, and that the pattern of spots
`
`Alcon Research, Ltd.
`Exhibit 1021 - Page 15
`
`

`

`in each layer is a spiral pattern which is substantially
`centro-symmetric to the optical axis of the eye.
`The
`result is a plurality of flat layers of photodisrupted
`stromal tissue, each layer being perpendicular to the
`5 optical axis. In accordance with the present invention, a
`plurality of superposed photodisrupted layers can be
`created by first photodisrupting the layer which is to be
`farthest from the epithelium, followed by successive
`photodisruption of additional layers in an anterior
`10 progression.
`Each successive layer in the anterior
`progression has a smaller diameter than the previous layer.
`The amount by which each layer is smaller than the previous
`one is determined by a particular geometric model which has
`been devised to result in the creation of the desired dome
`15 shaped cavity. Regardless of the number of layers created,
`it is important that every layer be at a safe distance from
`the epithelium, e.g. no closer than approximately 30 m.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`The novel features of this invention, as well as the
`20 invention itself, both as to its structure and its
`operation will be best understood from the accompanying
`drawings, taken in conjunction with the accompanying
`description, in which similar reference characters refer to
`similar parts, and in which:
`Figure 1 is a cross sectional view of the cornea of an
`eye shown in relationship to a schematically depicted laser
`unit;
`
`25
`
`30
`
`Figure 2 is a cross sectional view of the cornea of an
`eye showing the anatomical layers thereof;
`Figure 3 is a schematic representation of the relative
`positioning of adjacent laser beam spots and the resultant
`overlapping disruption of stromal tissue which occurs
`during implementation of the method of the present
`invention; and
`
`Alcon Research, Ltd.
`Exhibit 1021 - Page 16
`
`

`

`Figure 4 is a plan view schematic representation of a
`predetermined spiral pattern of focal spots and the
`resultant layer in which stromal tissue is photodisrupted
`by implementation of the method of the present invention.
`
`5
`
`DESCRIPTION OF THE PREFERRED EMBODIMENTS
`
`15
`
`Referring initially to Figure I, a cross section of
`part of an eye is shown and generally designated 10. For
`reference purposes, the portion of eye 10 which is shown
`includes the cornea 12, the sclera 14 and the lens 16.
`10 Further, in accordance with standard orthogonal ocular
`referencing coordinates, the z-axis or z direction is
`generally oriented on the optical axis of the eye 10.
`Consequently, the x and y directions establish a plane
`which is generally perpendicular to the optical axis.
`As best seen in Figure 2, the anatomy of the cornea 12
`of an eye 10 includes five different identifiable tissues.
`The epithelium 18 is the outermost tissue on the exterior
`of the cornea 12. Behind the epithelium 18, and ordered in
`a posterior direction along the z-axis, are Bowman's
`20 membrane 20, the stroma 22, Descemet's membrane 24, and the
`endothelium 26. Of these various tissues, the region of
`most interest to the present invention is the stroma 22.
`Returning for the moment to Figure 1, it will be seen
`that the method of the present invention incorporates a
`25 laser unit 28 which must be capable of generating a pulsed
`laser beam 30 having certain characteristics. Importantly
`the pulsed laser beam 30 should be monochromatic light
`having a wavelength (1) which will pass through all tissues
`of the cornea 12 without interacting with those tissues.
`30 Preferably, wavelength (A) of laser beam 30 will be in the
`range of from three tenths of a micron to three microns
`(1=0.3 m to 3 m). Also, the pulse repetition rate of laser
`beam 30 should be approximately in the range of from one
`hundred Hertz to one hundred thousand Hertz (0.1-100 kHz).
`
`8
`
`~
`
`~
`
`-m
`
`--
`
`Alcon Research, Ltd.
`Exhibit 1021 - Page 17
`
`

`

`An additional factor of great importance to the present
`invention is that the irradiance of laser beam 30 must be
`circumscribed and well defined. The main concern here is
`that the irradiance of beam 30 will, in large part,
`5 determine the photodisruptive capability of pulsed laser
`beam 30 on tissue of the stroma 22.
`Irradiance, or radiant flux density, is a measure
`of the radiant power per unit area that flows across a
`surface. As indicated by the following expression, the
`10 irradiance of laser beam 30 is a function of several
`variables. Specifically:
`
`(pulse enerqv)
`Irradiance = (pulse duration)(spot size)
`
`20
`
`From the above expression for irradiance it can be
`15 appreciated that, for a constant level of irradiance, the
`irradiance is proportional to the amount of energy in each
`pulse of beam 30.
`On the other hand, irradiance is
`inversely proportional to pulse duration and spot size.
`The significance of this functional relationship stems from
`the fact that the irradiance of pulsed laser 30 should be
`approximately equal to the optical breakdown threshold for
`stromal tissue 22. This threshold is known to be about two
`hundred gigawatts per square centimeter (200 GW/cm2 ).
`Insofar as each factor's contribution to irradiance is
`25 concerned, it is important to recognize that no one factor
`can be considered individually. Instead, the pulse energy,
`pulse duration and focal spot size of laser beam 30 are
`interrelated, and each characteristic is variable.
`For purposes of the present invention, the pulse
`30 duration of pulses in laser beam 30 is preferably in the
`range of from one hundred femtoseconds to ten nanoseconds,
`and preferably in the range of one to one hundred pico
`seconds (1-100 psec). As for the spot size to which each
`pulse is focused, the determinative consideration is that
`35 the spot size should be small enough to achieve optical
`
`Alcon Research, Ltd.
`Exhibit 1021 - Page 18
`
`

`

`10
`
`breakdown in a volume of stromal tissue 22 which is
`approximately equal to the volume of the focal spot. This
`relationship is perhaps best seen in Figure 3.
`In Figure 3, a succession of focal spots 32a-f are
`5 shown. All focal spots 32a-f are substantially spherical,
`or slightly ellipsoidal, and have substantially the same
`volume. As such, they can each be characterized as having
`a diameter 34. Focal spots 32a-f are shown arranged in a
`straight line 50 for the sake of simplicity of the drawing,
`but as will be explained, for the present invention, it is
`preferable for the focal spots 32a-f to be arranged on a
`spiral path. Figure 3 also shows the general relationship
`between each focal spot 32a-f and the associated cavitation
`bubble 36a-f which results when laser unit 28 is activated
`15 to irradiate a focal spot 32a-f.
`The cavitation bubble
`36a-f, like the associated focal spot 32a-f, will be
`generally spherical and can be characterized by a diameter
`38. As indicated above, it is preferable that diameter 38
`of each of cavitation bubbles 36a-f be the same as the
`20 diameter 34 of the corresponding focal spot 32a-f. This,
`however, cannot always be achieved. In any event, it is
`important that the volume of cavitation bubble 36a-f not be
`significantly larger than the volume of the focal spot 32a-
`f. For the present invention, it is important that the
`25 diameter 34 of focal spots 32a-f be less than about one
`hundred microns (100 m), and preferably about 10gm. It is
`preferable that the diameter 38 of cavitation bubbles 36a-f
`be no more than about twice the diameter 34 of focal spots
`32a-f.
`As indicated above, the focal spot 32a-f is
`substantially spherical. To configure focal spot 32a-f as
`close as possible to a sphere, rather than as an elongated
`ellipsoid, it is necessary for laser beam 30 to be focused
`through a rather wide cone angle 40 (see Figure 1).
`For
`35 purposes of the method of the present invention, cone angle
`40 should be in the range of from fifteen to forty five
`
`30
`
`Alcon Research, Ltd.
`Exhibit 1021 - Page 19
`
`

`

`degrees (150-450). Presently, the best results are known
`to be achieved with a cone angle of about thirty six
`degrees (36).
`For the practice of the method of the present
`5 invention, it is first necessary for the physician to
`somehow stabilize the eye 10. After the eye 10 has been
`stabilized, laser beam 30 is focused on a focal spot 32a at
`a first selected focal point 42a in the stroma 22.
`Specifically, for many procedures, the first focal point
`10 42a is located generally on the z-axis 44 behind the
`Bowman's membrane 20. As used here, "behind" means in a
`posterior direction or inwardly from the Bowman's membrane.
`Once laser beam 30 is so focused, the laser unit 28 is
`activated to irradiate the focal spot 32a at first focal
`15 point 42a. The result is that a cavitation bubble 36a is
`formed in stromal tissue 22, and a corresponding volume of
`stromal tissue is disrupted and removed from the stroma 22.
`The physical consequences of photodisruption of
`stromal tissue 22 at the first focal point 42a, and at
`20 other focal points 42b-f in the stroma 22, are manifold.
`Some tissue around the focal point 42a-f is, of course,
`removed. Additionally, however, by-products such as carbon
`dioxide (CO2), carbon monoxide (CO), nitrogen (N2 ) and water
`(H20) are formed. As stated above these by-products create
`25 a cavitation bubble 36a-f in the tissue of stroma 22. The
`volume of tissue removed is approximately the same as the
`volume of the cavitation bubble 36a-f.
`As indicated in Figure 3, once the cavitation bubble
`36a has been created, the laser beam 30 is repositioned for
`30 refocussing at another point 42b. In Figure 3 it is shown
`that the second focal point 42b is substantially adjacent
`to first focal point 42a and that both the second focal
`point 42b and first focal point 42a lie on a path 50.
`Importantly, the distance along path 50 between first focal
`35 point 42a and second focal point 42b is selected so that
`the adjacent volumes of disrupted tissue in cavitation
`
`Alcon Research, Ltd.
`Exhibit 1021 - Page 20
`
`

`

`bubbles 36a,b will overlap. In effect, the size of the
`cavitation bubbles 36a-f of disrupted tissue volume will
`determine the separation distance between selected focal
`points 42a-f along the path 50.
`As implied here,
`5 subsequent focal points 42c et seq. will also lie on the
`predetermined path 50 and the disrupted tissue volume at
`any respective focal point 42 will overlap with the volume
`of tissue disrupted at the previous focal point in stroma
`22.
`Consequently, the separation distance between focal
`10 points 42 on path 50 must be established so that tissue
`removal along the path 50 will be continuous.
`Figure 4 shows a plan view of a photodisrupted layer
`52 as seen looking toward the eye 10 along z-axis 44.
`Also, Figure 4 shows that the first focal point 42a and the
`15 sequence of subsequent points 42b-f all lie along the path
`50. Further, Figure 4 shows that the path 50 can be set as
`a pattern 62 and, as shown in Figure 4, this pattern 62 can
`be a spiral pattern. It is to be appreciated that the
`spiral pattern 62 can be extended as far as is desired and
`20 necessary to create the layer 52 of disrupted tissue
`volumes 36. Further, it is to be appreciated that layer 52
`may be curved to generally conform to the shape of the
`cornea's external surface. It is also to be appreciated
`that the final pattern 62 will be approximately centro-
`25 symmetric with respect to the optical axis (z-axis 44) of
`the eye 10.
`Referring back to Figure 2, it will be seen that a
`plurality of disrupted tissue volumes 36 can be juxtaposed
`to establish a continuous layer 52 of disrupted stromal
`tissue. Only a few of the disrupted tissue volumes 36 are
`shown in layer 52, for the sake of clarity of the drawing,
`but it should be understood that the entire layer 52 is
`disrupted as discussed above. As shown in Figure 2, a
`plurality of layers can be created in stroma 22 by the
`35 method of the present invention. Figure 2 shows a layer 54
`which is located in front of the layer 52 and a layer 56
`
`30
`
`_
`
`Alcon Research, Ltd.
`Exhibit 1021 - Page 21
`
`

`

`which is located in front of the layer 54. Layers 58 and
`60 are also shown, with layer 60 being the most anterior
`and smallest in diameter. As with layer 52, layers 54, 56,
`58, and 60 are entirely created by a plurality of disrupted
`5 tissue volumes 36. At least ten of these layers can be so
`created, if desired.
`Whenever a plurality of layers are to be created, it
`is important that the most posterior layer be created
`first, and that each successive layer be created more
`10 anteriorly than any previously created layer. For example,
`to create layers 52, 54, 56, 58, and 60, it is necessary to
`start first with the creation of the layer 52. Then, in
`order, layers 54, 56, 58, and 60 can be created.
`There are limitations as to how close any layer can be
`15 to the epithelium 18
`in order to avoid unwanted
`photodisruption of Bowman's membrane 20 and the epithelium
`18.
`Accordingly, no disrupted tissue volume 36 in any
`layer should be closer to the epithelium 18 than
`approximately thirty microns (30gm). Therefore, because it
`is anticipated that each layer will effectively encompass
`approximately a ten to fifteen micron thickness of tissue,
`it is necessary that first layer 52 be created at an
`appropriate location so that neither layer 52 nor any
`subsequent layer should eventually be located closer to the
`25 epithelium 18 than thirty microns.
`For a required myopic correction, it is desired to
`decrease the amount of corneal curvature by a given number
`of diopters (D), by increasing the corneal radius of
`curvature.
`Such a change in corneal curvature is
`30 accomplished by removing certain layers of the stromal
`tissue to create a dome shaped cavity entirely within the
`stromal layer 22.
`This cavity will then collapse,
`resulting in a flattening of the corneal anterior surface.
`This flattening will achieve the desired corneal curvature
`35 change. The desired corneal curvature change D in diopters
`can be computed according to the following equation:
`
`20
`
`__
`
`Alcon Research, Ltd.
`Exhibit 1021 - Page 22
`
`

`

`2(n-1) pol- 1-
`22po
`
`1/2
`
`d
`
`-Nt
`
`S 1/2
`
`2 2
`
`t 2p0o)
`
`4
`
`n-1o
`p
`
`where N is the selected number of intrastromal layers to be
`used to achieve the curvature change. The thickness of
`each layer, such as 10 m in the example given, is
`represented by t. The index of refraction of the cornea is
`5 represented by n. The corneal radius of curvature is p,
`with po being the preoperative radius. The selected outer
`diameter of the intrastromal cavity to be created, keeping
`in mind the minimum required separation from the epithelium
`18, is given by do. This selected outer diameter becomes
`10 the diameter of the first layer to be created. More effect
`is produced with smaller outer cavity diameters, and with
`more layers. The sensitivity to cavity diameter decreases
`sharply over a cavity diameter of approximately 5 mm.
`For myopic correction, the diameter of each layer 52,
`54, 56, 58, and 60 is smaller than the diameter of the
`layer previously created, to create a dome shaped cavity
`with its base oriented posteriorly, and its crown oriented
`anteriorly. A geometric an