REFRACTIVE SURGERIES

1
REFRACTIVE SURGERIES
2
CLASSIFICATION
-RK -PRK -LASIK -EPILASIK -LASEK -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
Patient selection

• Patients need to be fully informed about
  potential risks,benefits and realistic
  expectations
• Age gt 18 years
• Refractive status stable gt 1 year.
• Current FDA approval-
• Myopia-upto -12D
• Hyperopia upto 6D
• Astigmatism-upto 7D

6

• 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 or gt49D(Poor
  Optics).

7
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)

8
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)

9
PREOPERATIVE EVALUATION PRIOR TO LASIK

• Record UCVA and BCVA
• Dry and wet manifest
• Pupillometry-Infrared Pupillometer
• -Aberrometer
• Large pupil-Increased HOA perceived so increased
  glare
• -Can change Optic Zone
  

10

• 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.

11

• Tear film asessment-Schirmers,TBUT and Lissamine
  staining
• Blink Rate-(Normal---3-7/min)
• Corneal Topography-
• Schiempfug /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

12

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

13
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

14
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.

15

• 2nd step-Resection of corneal flap

Microkeratome
Femtosecond Laser (Intralase)
16

• Microkeratome-
• Uses Disposable blades
• Blade Plate can be set at 90µ,120µ,140µ,160µ
  and180µ.
• Nasal or superior hinge flaps can be created.
• Eg.Hansatome,XP Microkeratome, ACS, Carriazo
  Barraquer, Moria,Amadeus

17

• 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)

18

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

19

• 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-

20

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

21

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

22
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 bedgt280
• -Do surface ablation
• -Dont violate corneal
  topography diagnosis of forme-fruste keratoconus

23
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

24
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)

25
COMPLICATIONS OF LASIK

• Flap Complications-
• Button Hole-If Kgt50D,due to central corneal
  buckling.

26

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

SHORT FLAP
27

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

28

• .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
29

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

MICROSTRIAE
30

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

31

• 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

32

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

33

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

34

• 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

35

• 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

36

• 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.

37
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.

38

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

39

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

40
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.

41
AcuSof Corneal inlay
42
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).

43
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

44
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

45
Verisyse Phakic IOL
46
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

47
Veriflex (artiflex)

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

48
Posterior chamber lenses

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

49
STAAR ICL

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

50
(No Transcript)
51
Complications

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

52
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.

53
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.