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REFRACTIVE SURGERIES

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Iris fixated phakic IOL ... Prelex Clear Lens Extraction with use of Multifocal IOL s Combination of the two Microkeratome Femtosecond Laser (Intralase) ... – PowerPoint PPT presentation

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Title: REFRACTIVE SURGERIES


1
REFRACTIVE SURGERIES
  • Dr.Jyoti Shetty
  • Medical Director,
  • Bangalore West Lions Superspeciality Eye Hospital

2
CLASSIFICATION
-R.K. -PRK -LASIK -EPILASIK -LASEK -Conductive
Keratoplasty -Corneal Inlays and rings
-Clear Lens extraction for myopia -Phakic IOL -
Prelex Clear Lens Extraction with use of
Multifocal IOLs
Combination of the two
3
LASIK(Laser Assisted In Situ Keratomileusis)
  • Procedure using laser to ablate the tissue from
    the corneal stroma to change the refractive power
    of the cornea

4
  • Types of lasers used-
  • Excimer-Excited dimer of two atoms
  • -an inert gas(Argon)
  • -Halide(Fluoride)
  • which releases ultraviolet energy at193nm for
    corneal ablation

5
  • Non-Excimer solid state lasers-
  • 210nm Q switched diode pumped laser (laser off)
  • 213 nm Q switched diode pumped laser(Pulsar)

6
  • Advantage of Non-Excimer solid state lasers-
  • No toxic excimer gases
  • Wavelength closer to absorption peak of corneal
    collagenless thermal and collateral damage
  • Better pulse to pulse stability
  • Not absorbed by air,water,tear fluid-so less
    sensitive to humidity or room temperature
  • No purging with inert gases required.

7
Patient selection
  • Patients need to be fully informed about
    potential risks,benefits and realistic
    expectations
  • Age should be above 18 years
  • Refractive status should have been stable for at
    least 1 year.
  • Current FDA approval-
  • Myopia-upto -12D
  • Hyperopia upto 6D
  • Astigmatism-upto 7D

8
  • CCT such that minimum safe bed thickness
    left(250-270µ).Post op Corneal thickness should
    not be lt410µ.
  • Cornea not too flat or steep.lt36D orgt49D(Poor
    Optics).

9
CONTRAINDICATIONS
  • Systemic factors-
  • Poorly controlled IDDM
  • Pregnancy/lactation
  • Autoimmune / connective tissue disorders(RA,SLE,PA
    N etc)
  • Clinically significant Atopy,Immunosuppressed
    patients
  • Keloid tendency(esp PPK)
  • Slow wound healing-Marfans,Ehler-Danlos
  • Systemic Infection-(HIV,TB)
  • Drugs-Azathioprene,Steroids(Slow wound healing)

10
CONTRAINDICATIONS
  • Ocular Factors-
  • Glaucoma,RP(Suction Pressure-ON damage,Blebs)
  • Previous h/o RD or f/h of RD.
  • One eyed individual
  • Pre-existing dry eye,Keratoconus.pellucid
    marginal degeneration,Superficial corneal
    dystrophy,RCE,Uveitis,early Lenticular changes
  • h/o Herpetic Keratitis(one year prior to surgery)

11
PREOPERATIVE EVALUATION PRIOR TO LASIK
  • Record UCVA and BCVA Snellens V/a
  • Dry and wet manifest refraction(with 1
    cyclopentolate)
  • Pupillometry-Infrared Pupillometer
  • -Aberrometer
  • Large pupil-Increased HOA perceived so
    increased glare
  • -Can change Optic Zone

12
  • Slit Lamp Examination-
  • Rule out blepharitis, miebomianitis, pingecula,
    Pterygium,corneal neovascularization
  • Other contraindications for LASIK.
  • IOP by applanation
  • Dilated Fundus Examination to role out holes
    ,tears.

13
  • Tear film asessment-Schirmers,TBUT and Lissamine
    staining
  • Blink Rate-(Normal---3-7/min)
  • Corneal Topography-
  • Scanning slit/placido disc
  • Stop RGP lenses 2 weeks prior and soft lenses I
    wk prior
  • To rule out early Keratoconus and other ectasias
  • For mean K values

14
  • Pachymetry -For CCT (Ultrasound/Optical)
  • Contrast Sensitivity testing for pre-operative
    baseline.

15
BASIC STEPS AND MACHINE SPECIFICATIONS
  • Topical anasthesia-Proparacaine 0.5, Lignocaine
    4.
  • Surgical Painting and draping(Lint Free).
  • Lid speculum with aspiration.
  • Corneal marking-Orientation of free cap

16
Creation of flap-
  • 1st Step-Creation of suction by suction pump to
    raise the IOP to 65 mm Hg which is necessary for
    the microkeratome to create a pass and resect the
    corneal flap.
  • This is crosschecked with Barraquers tonometer.

17
  • 2nd step-Resection of corneal flap

Microkeratome
Femtosecond Laser (Intralase)
18
  • Microkeratome-
  • Uses Disposable blades
  • Blade Plate can be set at 120µ,140µ,160µ and180µ.
  • Nasal or superiorly hinge flaps can be created.
  • Eg.Hansatome,ACS,Carriazo Barraquer, Moria.

19
  • Femtosecond Laser for Flap-
  • Creates photodisruption using femtosecond solid
    state laser with wavelength of 1053nm.
  • Needs lower vacum.
  • Very short pulse with spot size of 3µ-High
    precision cutting device.
  • Any hinge can be made
  • Can make flaps as thin as 100µ(Sub Bowmanns
  • Keratomileusis)

20
  • Flap has vertical edges so reduced epithelial
    ingrowth.
  • Microkeratome flap thicker in periphery and
    thinner in the centre.Not so with
    Intralase(Planar).

21
  • 3rd Step-Delivery of Laser-
  • After flap is lifted, laser is applied to the
    stroma according to the ablation profile
    calculated by the machine.
  • Laser beam is delivered by the following ways
    depending on the machine-

22
  • Most machines employ a flying spot to deliver
    laser with the help of incorporated eye tracker.

23
  • 4th step-Reposition Of the Flap-
  • After irrigating interface ,flap reposited
  • Adhesion test-Striae test

24
ABLATION PROFILES
  • Wavefront Guided or customized ablation-to
    improve quality of vision by correcting higher
    order aberrations.
  • -Wavefront analysis on entire eye
  • done by Hartmann Shack
  • -Tracy

25
ABLATION PROFILES
  • Aspheric Ablation-Normal LASIK converts prolate
    cornea to oblate structure.(Central
    flattening,steep in periphery.) which induces
    higher order aberrations.
  • To reduce this and preserve the prolate
    structure,Q value is calculated and altered to
    give a more aspheric ablation.

26
COMPLICATIONS OF LASIK
  • Under/over correction and regression (over time).
  • Post op Keratectasia
  • Presents 1-12 months
  • Progressive regression
  • Treatment-RGP,Corneal transplant.
  • Prevention- Leave residual stromal bed
  • -Do surface ablation
  • -Dont violatecorneal
    topography diagnosis of forme-fruste keratoconus

27
COMPLICATIONS OF LASIK
  • Night vision disturbances-Haloes/Glare
  • Decenteration and central islands.
  • Post Lasik Dry eye-
  • Fluctuating vision,SPK
  • Temporary neuropathic cornea
  • Confocal microscopy-90 reduction in corneal
    nerve fibres-regeneration by 1 year.
  • Rx-Preservative Free lubricants

28
COMPLICATIONS OF LASIK
  • Post op Glaucoma(Pseudo DLK)-Steroid induced.
  • Vitreoretinal Complications-
  • Increased risk of RD due to alteration of
    anterior vitreous by suction ring-Risk 0.08.
  • PVD(0.1 Risk)
  • Macular Hemorrage(0.1 Risk)

29
COMPLICATIONS OF LASIK
  • Flap Complications-
  • Button Hole-If Kgt50D,due to central corneal
    buckling.
  • .

30
  • Irregular thin flap-Inadequate suction/old blade
  • Short Flap-Hinge encroaches on visual axis-Due to
    jamming of microkeratome with hair/FB

SHORT FLAP
31
  • Free Cap-Due to flat pre op K(lt38D).

32
  • .Flap undulations-
  • Macrostriae-Linear lines in clusters,seen on
    retroillumination.
  • Causes-Incorrect position of flap
  • -Movement of flap after
    LASIK
  • Rx-Lift flap
  • -Rehydrate and float it back
  • -Check for flap adhesion

MACROSTRIAE
33
  • Microstriae-Flap in position but fine wrinkles
    seen superficially
  • -Due to large myopic ablation
  • -Rx- Observe.They resolve
    spontaneously

MICROSTRIAE
34
  • Bleeding during flap cutting due to corneal
    neovascularization in contact lens users

35
  • Interface Inflammation(Sands Of
    sahara/DLK)-Non-Infective inflammation at the
    interface seen in 1st week after LASIK.
  • Diffuse,confluent,white granular material at the
    interface 1-7 days after LASIK.
  • Slight CCC
  • No AC reaction
  • Reduced Visual acuity

36
  • Grade 1-
  • Focal involvement - Normal V/A.
  • Rx Intensive topical steroids.

37
  • II Diffuse involvement Normal V/A.
  • Rx-Add systemic steroids.

38
  • III Diffuse confluent granular deposits-
  • Reduced V/A.No AC reaction.
  • Rx-Same as aboveAntibiotics
  • IV - Diffuse confluent granular deposits intense
    central striae.
  • Marked Reduced V/A
  • Rx-Interface irrigation above

39
  • Causes-Proposed Theory
  • Bacterial cell wall endotoxin
  • Cleaning solution toxicity
  • Talc from gloves
  • Miebomian secretions

40
  • Infection-Potential complication as any surgical
    procedure

41
  • Epithelial ingrowth-Presents 1-3 months after
    LASIK.
  • Causes-Epithelial cells trapped under flap
  • Risk factors-Peripheral epithelial defects
  • -Poor flap adhesion
  • -Buttonholed flaps
  • -Repeat LASIK

42
  • Classification-
  • GRADE 1-Faint white line lt2mm from flap edge
  • GRADE 2-Opaque cells lt2mm from flap edge with
    rolled flap edge
  • GRADE 3-Grey to white fine opaque line extending
    gt2mm from flap edge.
  • GRADE 4-If ingrowth gt2mm from edge with
    documented progressionLift flap and remove the
    sheets of epithelium.Can use MMC.

43
EPILASIK / LASEK
  • Anterior stroma of cornea (ant. 1/3 rd)
  • has stronger interlamellar connections than
    post. 2/3rd.
  • So surface ablation preserves the structural
    integrity better than LASIK especially in the
    correction of moderate to high myopia.

44
  • LASEK-Camellins Technique-
  • 20 absolute alcohol used for 20-35s. To raise
    epithelial flap.
  • Flap reposited after ablation

45
  • EPILASIK- Epithelial keratome used to lift
    epithelial flap of about 60-80µ thick.
  • Epithelial keratomes use
  • - PMMA blades
  • -Metal Epithelial Separator

46
CONDUCTIVE KERATOPLASTY
  • Uses mild heat from radiofreqoency waves to
    shrink collagen in the periphery of the
    cornea---This steepens the paracentral cornea.
  • Used for hyperopia (1 2.25D) and presbyopia.
  • C.K. spots are applied with a probe in rings with
    a dia. Of 6/7/8 mm.
  • 8 spots are given in each diameter ring.

47
7
6
5mm
48
  • Drawbacks-
  • Regression and retreatment in 100 cases after 6
    months.
  • Induced cylinder gt1D reported in many cases.
  • Usually done in one eyeMany have intolerance to
    monovision.

49
CORNEAL INLAYS
  • Increase the depth of focus by using pinhole
    optics.
  • Inlays have 1.6mm centre with 3.6mm surround.
  • Near vision improves by 1.5D with no loss of
    distant vision.
  • Used in the non dominant eye.
  • These are hydrogel based.Placed in a tunnel
    200-400 µ deep in centre of cornea.

50
AcuSof Corneal inlay
51
Phakic IOLs
  • An intra-ocular lens is placed inside the eye in
    front of the patients natural lens.
  • These are available in three types
  • Anterior chamber angle fixated IOL Nuvita
    (Bausch Lomb), Kelman duet, I care (corneal),
    Vivarte (Ciba vision)
  • Iris supported phakic IOL Verisyse/ Artisan
    (AMO/Ophtec)
  • Plate lens that fits between the iris the
    crystalline lens Starr implantable contact lens
    (ICL), PRL (Ciba).

52
Indications
  • Age above 18 years
  • Stable refraction for one year
  • Patients not suitable for LASIK/LASEK due to high
    powers or thin corneas
  • AC depth 3.0 mm
  • Endothelial count gt2000cells/cumm
  • No other ocular pathology

53
Contraindications
  • Myopia other than axial myopia
  • Corneal dystrophy/ Endothelial cell count
    lt2000cells/cumm
  • Anterior chamber depth less than 3.0mm
  • History of uveitis
  • Presence of anterior/posterior synechiae
  • Glaucoma or IOP higher than 20 mmHg
  • Evidence of nuclear sclerosis or developing
    cataract
  • Personal or family history of retinal detachment
  • Diabetes mellitus

54
Angle supported anterior chamber phakic IOLs
Rigid lenses
IOL NuVita MA20 ZSAL-4 Phakic6
Company Bausch Lomb Morcher M C
Prev. model ZB5M / ZB5MF (Baikoff) ZSAL 1-3 ________
Material PMMA PMMA PMMA
Optic 5.0 mm 5.8 mm 6.0 mm
Eff.opt.zone 4.5 mm 5.3 mm ??
Haptic optic 12 -13.5mm 12.0/13.5mm 12 14mm
Diopters (D) - 3.0 to 23.0 D -20.0 to 10.0D Plano concave (-20 to -3.0) Convexo-concave (-2.5 to 4.5) Biconvex (5 to 10) - 2.0 to -25.0D 2.0 to 10.0D
55
Angle supported anterior chamber phakic IOLs
Foldable IOls
IOL Vivarte I CARE Kelman Duet The Vision Membrane
Company Ciba vision Corneal (france) Vision membrane technologies
Material Hydrophillic acrylic (RI 1.47) HEMA 26 Optic- Silicone Haptic PMMA Silicone
Optic 5.5 mm 5.75 mm 5.5 mm 7.0 mm
Haptic optic 12-13 mm 12-13.5 mm 12-13.5 mm
Diopters (D) -7.0 to -25.0 D -20.0 to 10.0D injectable lens -8.0 to -20.0 D
56
Anterior Chamber Phakic IOL
57
Kelman Duet phakic IOL
  • Two piece phakic IOL. The PMMA haptic is first
    snaked through a 1.5mm incision. The silicone
    optic is then compressed inserted. Once the
    optic unfolds in the anterior chamber the two
    tabs on either side of the optic are snapped into
    projections on the haptic. The main advantage of
    this lens is that the optic can be exchanged with
    a new one if the patients refraction changes.

58
Iris fixated phakic IOL Verisyse Phakic IOL
  • Most commonly used phakic IOL
  • One-piece design

59
Verisyse Phakic IOL
60
Pre-op assesment for phakic IOL
  • Refraction Objective subjective acceptance at
    12mm vertex distance
  • Anterior chamber depth from epiuthelium to
    endothelium
  • Anterior posterior segment examinations
  • K-reading Topography Orbscan-II
  • Intra-ocular pressure
  • White to white measurement
  • Specular microscopy

61
Veriflex (artiflex)
  • Foldable iris claw lens. It is a modification of
    Verisyse (Artisan) phakic IOl.

62
Posterior chamber lenses
  • These phakic IOLs are placed in the posterior
    chamber between the iris the crystalline lens.
    These are
  • Starr ICL
  • Cibavision PRL

63
STAAR ICL
  • The STAAR Collamer ICL and the TORIC ICL are
    posterior chamber phakic intraocular lenses. Made
    of Collamer, STARRs proprietary collagen
    copolymer (colagen/HEMA), the lens rests behind
    the iris in the ciliary sulcus.

64
(No Transcript)
65
Procedure
  • The lens is gently folded and injected into the
    anterior chamber through a 3.0 mm, temporal,
    clear corneal incision. The ICL is then carefully
    positioned by manipulating the footplates of the
    lens posterior to the iris plane and and into the
    sulcus. Pre-operative YAG iridotomy is essential.

66
Complications
  • ICL decentration
  • Pupillary block
  • Pigment dispersion
  • Subcapsular cataract

67
Advantages of phakic IOLs over laser corrective
procedures
  • A higher range of refractive errors can be
    corrected
  • Reversible Phakic IOL implantation is a
    potentially reversible procedure
  • Safe No structural changes are induced. Hence it
    is safe in any eye with high error also thin
    corneas.
  • Better quality of vision Quality of vision
    (contrast sensitivity) is better than the laser
    refractive procedures in eyes with higher
    refractive errors and no induced higher order
    aberrations. There is also a considerable
    improvement in BVCA with these lenses because of
    the magnification effect.
  • Highly skilled procedure Prevents misuse of the
    procedure.

68
Bioptics
  • Bioptics is a combination of phakic IOL and
    LASIK. Bioptics is done for the correction of the
    residual spherocylindrical power when a spherical
    implant is used.

69
THANK YOU
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