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`
`1
`
`Section 8
`
`2001-2002
`External Disease
`and Cornea
`
`1//
`
`,
`
`-+4
`
`® THE FOUNDATION
`
`OF THE AMERICAN ACADEMY
`OF OPHTHALMOLOGY
`
`Petitioner - New World Medical
`Ex. 1009, p. 1 of 9
`
`

`

`Basic and Clinical Science Course
`
`External Disease
`and Cornea
`Section 8
`
`2001-2002
`
`(Last major revision 1998-1999)
`
`® THE FOUNDATION
`
`OF THE AMERICAN ACADEMY
`OF OPHTHALMOLOGY
`
`LEO
`
`IF E LONG
`
`EDUCATION MAIM
`
`OPHTHALMOLOGIST'
`
`Petitioner - New World Medical
`Ex. 1009, p. 2 of 9
`
`

`

`LEO
`
`The Basic and Clinical Science Course is one component
`of the Lifelong Education for the Ophthalmologist (LEO)
`framework, which assists members in planning their con-
`tinuing medical education. LEO includes an array of clin-
`ical education products that members may select to form
`individualized, self-directed learning plans for updating
`their clinical knowledge. Active members or fellows who use LEO
`components may accumulate sufficient CME credits to earn the LEO
`Award. Contact the Academy's Clinical Education Division for further
`information on LEO.
`
`The American Academy of Ophthalmology is accredited by
`the Accreditation Council for Continuing Medical Education
`to provide continuing medical education for physicians.
`
`The American Academy of Ophthalmology designates this
`CME activity for up to 40 hours in category 1 credit toward
`the AMA Physician's Recognition Award. Each physician
`should claim only those hours of credit that he/she has
`actually spent in the educational activity.
`
`The Academy provides this material for educational purposes only. It is
`not intended to represent the only or best method or procedure in every
`case, nor to replace a physician's own judgment or give specific advice
`for case management. Including all indications, contraindications, side
`effects, and alternative agents for each drug or treatment is beyond the
`scope of this material. All information and recommendations should be
`verified, prior to use, with current information included in the manufac-
`turers' package inserts or other independent sources, and considered in
`light of the patient's condition and history. Reference to certain drugs,
`instruments, and other products in this publication is made for illustrative
`purposes only and is not intended to constitute an endorsement of such.
`Some material may include information on applications that are not con-
`sidered community standard, that reflect indications not included in
`approved FDA labeling, or that are approved for use only in restricted
`research settings. The FDA has stated that it is the responsibility of the
`physician to determine the FDA status of each drug or device he or she
`wishes to use, and to use them with appropriate patient consent in com-
`pliance with applicable law. The Academy specifically disclaims any and
`all liability for injury or other damages of any kind, from negligence or
`otherwise, for any and all claims that may arise from the use of any rec-
`ommendations or other information contained herein.
`
`Copyright° 2001
`The Foundation of the American Academy of Ophthalmology
`All rights reserved
`Printed in the United States of America
`
`Petitioner - New World Medical
`Ex. 1009, p. 3 of 9
`
`

`

`CHAPTER XXV
`
`Basic Science of
`Keratorefractive Surgery
`
`Refractive surgery encompasses a broad range of procedures to change the refrac-
`tion of the eye. BCSC Section 3, Optics, Refraction, and Contact Lenses, discusses
`the optical considerations for these procedures. Such procedures include techniques
`to alter the basic shape of the cornea or its ability to refract light. A classification of
`terms used in "keratospeak" is summarized in Table XXV-1.
`Currently, the most prevalent refractive surgery is cataract removal with intra-
`ocular lens implantation, which is covered in BCSC Section 11, Lens and Cataract.
`Other related techniques include removal of the natural lens to treat myopia (clear
`lens extraction), removal and replacement of the natural lens with 10Ls to treat both
`hyperopia or myopia, or insertion of an artificial lens without natural lens removal
`(phakic 10L). All are effective methods for correcting refractive errors, but safety has
`not been established; the rate of complications including retinal detachment and
`loss of corneal endothelial cells is undetermined.
`Refractive surgery involving the cornea is rapidly changing with advances in
`technology. Chapter XXVI discusses the clinical aspects of keratorefractive surgery,
`and chapter XXVII covers laser techniques. Schematic illustrations of the more fre-
`quent procedures are shown later in this chapter.
`
`Corneal Optics
`
`Zones of the Cornea
`
`For more than 100 years the corneal shape has been recognized as aspheric.
`Typically, the central cornea is about 3 D steeper than the periphery, a positive shape
`factor. Clinically, the cornea is divided into zones that surround fixation and blend
`into each other. The central zone of 1-2 mm closely fits a spherical surface. Adjacent
`to the central zone is a 3-4 mm doughnut with an outer diameter of 7-8 mm. Termed
`the paracentral zone, this doughnut represents an area of progressive flattening from
`the center. Adjacent to the paracentral zone is the peripheral zone with an outer
`diameter of approximately 11 mm, and adjoining this is the limbus with an outer di-
`ameter on average of 12 mm. The central and paracentral zones are primarily
`responsible for the refractive power of the cornea (Fig XXV-1, see p 442).
`Together, the paracentral and central zones constitute the apical zone as used
`in contact lens fitting. The peripheral zone is also known as the transitional zone,
`as this is the area of greatest flattening and asphericity of the normal cornea. The
`limbal zone sits adjacent to the sclera and represents an area of steepening of the
`cornea prior to joining the sclera at the timbal sulcus.
`
`437
`
`Petitioner - New World Medical
`Ex. 1009, p. 4 of 9
`
`

`

`contraindicated
`If penetrating keratoplasty
`
`in keratoconus
`Astigmatism and myopia
`
`development
`FDA core study; in laboratory
`indicated, e.g., infant aphakia
`If contact lens and IOL contra-
`
`Myopia
`
`Aphakia, hyperopia
`
`In development in Moscow
`
`Hyperopia
`
`Early clinical trials
`Phase III FDA trials in U.S.
`
`In laboratory development
`
`Early clinical trials
`
`and control
`Computerized calculations
`no suture
`Appositional, overlay,
`Suture techniques:
`
`Hyperopia
`Myopia, astigmatism
`
`Myopia
`Myopia
`
`Myopia
`
`Myopia, hyperopia, aphakia
`aphakia
`Myopia (MKM) hyperopia,
`
`Plano lenticule
`coated hydrogel)
`Synthetic (e.g., collagen and
`■ Lyophilized
`■ Excimer laser
`■ Suction mold (BKS)
`■ Cryolathe
`Human donor lenticule
`with trephine and left in place)
`except stromal button is cut smaller
`Autokeratophakia (same as KM in situ,
`■ Flap disc (LASIK)
`■ Complete disc
`Excimer laser (ArF, 193 nm)
`microkeratome)
`Keratokyphosis (refractive mold in
`Microkeratome (piano excision)
`■ Donor (homoplastic)
`■ Patient (autoplastic)
`Source of tissue for disc
`■ Excimer laser (ArF, 193 nm)
`with suction mold (BKS)
`■ Nonfreeze—microkeratome
`■ Barraquer's cryolathe
`stromal cut
`Methods of making refractive
`■ Oscillating or rotating blade
`■ Manual or mechanical advance
`Microkeratome techniques
`
`Epikeratoplasty (Epi)
`
`(carving corneal bed)
`KM in situ
`
`with microkeratome)
`(KM, cutting corneal disc
`Keratomileusis
`
`Lamellar
`
`COMMENT
`
`REFRACTIVE ERROR TREATED
`
`TECHNIQUE OR MATERIAL
`VARIATIONS OF SURGICAL
`
`BASIC SURGICAL TECHNIQUE
`
`KERATOPLASTY
`TYPE OF REFRACTIVE
`
`CLASSIFICATION OF CORNEAL REFRACTIVE SURGERY
`
`TABLE XXV-1
`
`Petitioner - New World Medical
`Ex. 1009, p. 5 of 9
`
`

`

`Continued
`
`scopic or keratometric control
`Often staged under kerato-
`
`plus refractive cylinder)
`sleep corneal meridian (axis of
`Incision made transverse to
`Reduce overcorrection
`
`Early clinical trials
`Under development in Russia
`
`In laboratory development
`
`Phase III trials in U.S.
`
`In laboratory development
`
`In laboratory development
`
`Compound myopic astigmatism
`and posttraumatic)
`Secondary (e.g. postoperative
`Primary (naturally occurring)
`Astigmatism
`
`Myopia
`
`degeneration)
`thinning (e.g., Terrien
`Astigmatism from marginal
`(e.g., keratoconus)
`Irregular astigmatism
`Hyperopia
`
`Aphakia
`
`Myopia
`
`Myopia
`
`Aphakia
`
`Aphakia
`
`Seldom used
`Early clinical trials
`
`Aphakia, myopia
`Aphakia, myopia
`
`Isolated straight or arcuate (T cuts)
`Open and suture wounds
`Staged with repeated adjustments
`Single nomogram
`
`Transverse (TK, AK)
`
`Radial
`
`keratotomy)
`(refractive
`Keratotomy
`
`Crescentic
`
`Central
`Single deep microkeratome pass
`Autokeratophakia; folded corneal flap
`
`■ Gel injection adjustable (volume)
`— Fixed volume: PMMA, silicone
`■ Intracorneal ring
`Annular lamellar dissection
`■ Fresnel hydrogel
`(e.g., fenestrated polysulfone)
`■ High index of refraction
`Lamellar pocket
`■ Human donor lenticule
`■ Hydrogel lenticule
`Microkeratome (lamellar bed)
`
`keratoplasty
`
`Lamellar keratoplasty
`Lamellar keratotomy
`
`(ICL, ICR, keratophakia)
`Intracorneal lens or ring
`
`10L, intraocular lens; ICL, intracorneal lens; ICR, intracorneal ring; TK, transverse keratotomy; AK, astigmatic keratotomy; PK, penetrating keratoplasty.
`KEY: KM, keratomileusis; MKM, myopic keratomileusis; BKS, Barraquer-Krumeich-Swinger; ArF, argon fluoride; PMMA, polymethylmethacrylate; Epi, epikeratoplasty;
`
`Postoperative astigmatism
`
`Postoperative astigmatism
`
`Interrupted radial
`Interrupted transverse
`
`■ Transverse incision in donor
`wound
`■ Wound separation or incision in
`(relaxing incision)
`Modification of penetrating keratoplasty
`■ Trapezoidal (Ruiz, semiradial)
`■
`■
`■ Between radial
`Combined with radial
`
`Petitioner - New World Medical
`Ex. 1009, p. 6 of 9
`
`

`

`In laboratory development
`seldom used
`Excimer laser (193 nm),
`in U.S. (hyperopia in FDA trial)
`—1.00 to —4.00 D of astigmatism
`
`—10.00 D in U.S.
`FDA approved for —1.00 to
`
`Myopia
`
`Myopia, astigmatism
`
`radial, Epi, PK)
`Secondary (e.g., after
`occurring)
`Primary (naturally
`
`hyperopia
`Myopia, astigmatism,
`
`Seldom used
`
`Astigmatism
`
`Seldom used
`Acts like wedge resection
`
`Hyperopia
`
`Acts like keratotomy
`
`Postoperative astigmatism
`High against-the-rule astigmatism
`Postoperative astigmatism
`
`Naturally occurring astigmatism
`
`Length <5 mm
`incision acts like TK
`Limbal or corneal cataract
`
`Few or no sutures
`Sclera! tunnel
`
`Nd:YAG laser (532 nm)
`■ Nanosecond frequency—doubled
`■ Picosecond ND-YLF (1053 nm)
`Nd:YAG laser
`Intrastromal photodisruption with
`transverse)
`Linear laser keratectomy (radial,
`(213 nm)
`■ 5th harmonic Nd:YAG laser
`■ Excimer laser (ArF, 193 nm)
`ablation, and multiple zone ablation)
`(central sculpting, large area
`Photorefractive keratectomy (PRK)
`
`with double running suture
`Circular, partial-thickness trephination
`—With transverse (hex-T)
`—Nonconnected
`Hexagonal
`■ Placement of compression sutures
`■ Distribution of tension on running
`■ Removal or cutting of interrupted
`Suture adjustment
`
`—Transverse keratotomy
`—Scleral flap recession or resection
`
`—Wound revision
`—Transverse keratotomy
`
`■ Postoperative
`
`incision on steep meridian
`adjust wound size, center
`reduce preexisting astigmatism,
`
`—Astigmatism neutral cataract
`lntraoperative
`
`■
`Modification of cataract surgery
`
`incision
`
`—Manipulation of incision to
`
`Laser
`
`Keratectomy
`
`Circumferential
`
`(cont)
`Transverse (TK, AK)
`
`(cont)
`keratotomy)
`(refractive
`Keratotomy
`
`COMMENT
`
`REFRACTIVE ERROR TREATED
`
`TECHNIQUE OR MATERIAL
`VARIATIONS OF SURGICAL
`
`BASIC SURGICAL TECHNIQUE
`
`KERATOPLASTY
`TYPE OF REFRACTIVE
`
`TABLE XXV-1. CLASSIFICATION OF CORNEAL REFRACTIVE SURGERY (Continued)
`
`Petitioner - New World Medical
`Ex. 1009, p. 7 of 9
`
`

`

`BCSC Section 11, Lens and Cataract.
`Modified from Waring GO III. Making sense of keratospeak IV: classification of refractive surgery, 1992. Arch Ophthalmol. 1992;110:1385-1391. For IOL implants, see
`IOL, intraocular lens; ICL, intracorneal lens; ICR, intracorneal ring; TK, transverse keratotomy; AK, astigmatic keratotomy; PK, penetrating keratoplasty.
`KEY: KM, keratomileusis; MKM, myopic keratomileusis; BKS, Barraquer-Krumeich-Swinger; ArF, argon fluoride; PMMA, polymethylmethacrylate; Epi, epikeratoplasty;
`
`sutures in flat meridian
`Early placement of interrupted
`meridian
`Early opening of wound in steep
`Adjustment of running suture
`sutures in steep meridian
`Selective removal of interrupted
`
`or after surgery
`Suture adjustment during
`
`Myopia, keratoconus
`Hyperopia, aphakia
`
`Donor undersized
`Donor oversized
`
`Donor—host size disparity
`
`Seldom used
`
`Astigmatism
`
`Hyperopia
`
`Arcuate in flat meridian
`pattern
`Peripheral, intrastromal, radial
`
`thermocoagulation
`Deep stromal hot needle
`
`(refractive aspects)
`keratoplasty
`Penetrating
`
`In clinical trials
`
`Hyperopia/myopia
`
`Astigmatism
`
`In design phase
`
`In laboratory development
`
`Astigmatism
`
`Astigmatism
`
`To be evaluated
`
`myopia and hyperopia
`without concurrent treatment for
`Treatment in flat meridian with or
`peripheral or paracentral
`Radial or circular pattern,
`
`■ Fine water stream
`■
`superficial keratectomy
`Mechanical central refractive
`marginal degenerations
`or flap for Terrien or pellucid
`Crescentic lamellar corneal tuck
`cataract extraction
`■ Wound repair during or after
`■ Wedge resection after PK
`Crescentic wedge
`Laser adjustable synthetic Epi
`(1064 nm)
`■ Nanosecond Nd:YAG laser
`
`Rotating blades
`
`Thermokeratoplasty Holmium YAG laser
`
`(2.06 pm)
`
`Mechanical
`
`Petitioner - New World Medical
`Ex. 1009, p. 8 of 9
`
`

`

`
`
`
`Paracentral
`zone
`
`Limbus
`
`FIG XXV—l—Topographic zones of the cornea. (illustration by Christine Gralapp.)
`
`Pupil border
`
`The optical zone of the cornea is that portion that overlies the entrance pupil of
`the iris but is physiologically limited to approximately 5.4 mm because of the Stiles-
`Crawford effect. The corneal apex is the point of maximum curvature, typically
`temporal to the center of the pupil. The corneal vertex is the point located at the
`intersection of the patient’s line of fixation and the corneal surface. It is represented
`by the corneal light reflex when the cornea is illuminated coaxially with fixation.
`The corneal vertex is the center of the keratoscopic image and does not necessarily
`correspond to the point of maximum curvature at the corneal apex (Fig XXV-2).
`
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`
`Shape, Curvature, and Power
`Three topographic properties of the cornea are important to its optical function: the
`underlying shape, which determines its curvature and hence its refractive power.
`Shape and curvature are geometric properties of the cornea. Power is the functional
`property. Historically, power was the first parameter of the cornea described, and
`diopters representing the refractive power of the central cornea were accepted as the
`basic unit of measurement. The advent of contact lenses and refractive surgery has
`made knowing the overall shape and its related property of curvature more impor-
`tant. BCSC Section 3, Optics, Refraction, and Contact Lenses, covers these topics in
`greater depth.
`The refractive power of the cornea is determined by Snell’s law, or the law of
`refraction. The ophthalmometer (keratometer) empirically estimates corneal power
`by reading four points of the central 2.8—4.0 mm zone. These points do not rep—
`resent the corneal apex or vertex but are a clinically useful estimation of central
`corneal power. The radius of curvature is calculated from the simple vergence for—
`
`mula using the known object size and measuring the distance with doubling prisms
`
`
`
`
`Petitioner - New World Medica
`
`Ex. 1009, p. 9 of 9
`
`Petitioner - New World Medical
`Ex. 1009, p. 9 of 9
`
`