REFRACTIVE SURGERY

1
REFRACTIVE SURGERY the optometrist
RH/OPTOM/UKZN 2007
2

• near sighted people have sought ways to get rid
  of their glasses for centuries. Tradition says
  that ancient Chinese (presumably myopic) slept
  with sandbags on their eyes to flatten their
  corneas

3

• It is certain that Purkinje tried the same thing
  in the 1820s with only temporary improvement of
  his 5D of myopia.
• In the mid 1800s, Dr J Ball advertised a small
  mallet mounted on a spring in a eye cup that
  struck the cornea through the closed eyelid,
  pounding it flat. It restores your eyesight and
  renders your spectacles useless he claimed.

4

• RIDICULOUS?
• PERHAPS

5
INEFFECTUAL??

• CERTAINLY!!!
• BUT NOT ALL SUCH NOTIONS WERE EITHER RIDICULOUS
  OR INEFFECTUAL - THEY MAY JUST HAVE BEEN
  UNTIMELY (Bores 1993)

6

• McDonnell (1999) postulated that if we want to
  have a feel for the way ophthalmology is going in
  the next millennium, then we need look no further
  than refractive surgery today

7
WHY OPT FOR REFRACTIVE SURGERY??

• PREVIOUSLY
• vocation
• sport
• rx/C/L intolerance

• NOW
• cosmesis
• frustration with use of spex and C/L
• Improved unaided VA

8
AIM OF REFRACTIVE SURGERY

• alter refr state of eye gt enable px to see
  without visual aids
• refr surgery divided into FOUR major areas
• 1. INCISIONAL TECHNIQUES
• 2. INTRAOCULAR LENSES
• 3. THERMAL TECHNIQUES
• 4. LAMELLAR PROCEDURES

9
INCISIONAL TECHNIQUES(use of incisions)

• Eg. RADIAL KERATOTOMY (RK)
• Sato,1939, intro as solution to keratoconus
  modified by Fyodorov
• procedure involves radial cuts on epithelial side
  of cornea to stroma
• pattern spokes of a bicycle wheel
• between 4-16
• Extra-pupillary region
• principle incisions gt side of cornea to bulge
  gt central corneal flattening gt reduction in
  myopia (2-3D)

10
INTRAOCULAR LENSES(use of implants)

• Eg. INTRASTROMAL CORNEAL RINGS
• makes use of intrastromal corneal ring segments
  INTACS (PMMA)

11
INTACS

• The ring segments flatten your cornea similarly
  to the way you can flatten the top of a tent by
  pushing on the sides.

12
INTRASTROMAL RINGS cont..

• Segmentsgt flatten central cornea - adv no
  removal of tissue
• Initially indicated for low myopia (1-3D) and min
  astig lt 1.00D
• Nowgt Advocated for keratoconics
• adv reversible, natural corneal physiology
  maintained, no use of lasers

13
THERMAL PROCEDURES(use of heat)

• Eg. THERMOKERATOPLASTY
• involves creation of two sets of 8 spot burns
  using holmium YAG laser - in ring pattern -
  peripheral cornea
• Heat gt coagulation - up to 90 of corneal depth
• Coagulation gt collagen shrinkage in periphery gt
  generalised central steepening gt correct
  hyperopia (up to 2.50D

14
LAMELLAR PROCEDURES(removal of corneal tissue
excimer laser

• Laser Assisted in situ keratomileusis (LASIK)
• Laser Epithelial Keratomileusis (LASEK)
• Epithelial LASIK (EPI-LASIK)

15
WHAT IS AN EXCIMER LASER?

• Acronym EXCIMER excited dimer
• refers to inert gas eg. Argon or Xenon bound with
  a halogen eg. Fluorine or Chloride
• combinationdiatomic gas halide - temporary
  excited state

16
EXCIMER LASER

• during decay gt emits UV of 193nm ? gt removal of
  controlled amts of tissue with extreme precision

17
EXCIMER LASER
18
LASER ASSISTED IN-SITU KERATOMILEUSIS (LASIK)

• Concept first intro by Jose Barraquer, 1964
• founder Dr Ionas Pallikaris- first to use
  microkeratome to cut thin flap of cornea and
  laser to remove tissue
• christened tech LASIK
• KERATOMILEUSIS to shape cornea
• IN-SITU in place
• therefore, LASIK to shape cornea in place

19
PRINCIPLES OF LASIK

• To treat MYOPIA, the central cornea must be made
  flatter. This is accomplished by removing tissue
  from the center of the cornea.

20
PRINCIPLES OF LASIK

• To treat HYPEROPIA, the central cornea must be
  made steeper. This is accomplished by directing
  the laser beam to remove tissue from around this
  area.

21
PRINCIPLES OF LASIK

• To treat ASTIGMATISM the cornea must be made more
  spherical. By changing the pattern of the beam,
  tissue is removed in one direction more than the
  other.

22
PRE-LASIK PATIENT EDUCATION

• Residual prescription - only those patient that
  are still keen should be considered.
• Can expect a ? in BCVA - many instances - 6/12-
  6/9. A simulation using trial lenses -
  demonstrate the possible corrected visual acuity
  ffg LASIK

23
PATIENT EDUCATION

• presbyopia and the need for reading spectacles
  later on.
• The option of monovision should be presented -
  possibly simulated using contact lenses.
• Patients with large pupil diameters in dim
  illumination gt possibility of haloes and poor
  vision at night.

24
INCLUSION CRITERIA

• highly motivated - reasonable expectations -
  risks and complications
• Myopia initially only for high myopia gt6D but
  recently for all errors therefore no clear cut
  myopic ranges, varies, lower limit 1.00D.
  Upper limit some up to 30D recent research
  shown often upper limit 16D

25
INCLUSION CRITERIA

• hyperopia 1-3D (higher incidence of regression
• astig up to 6D
• Adequate corneal thickness, gt 45O ?m

26
INCLUSION CRITERIA

• Age gt 21 years old, no max age.
• stable refraction over past 24 months
• Central Ks gt 39D to ensure optimal corneal
  surface to work on (poor flaps) lt 47D risk of
  keratoconus
• Informed consent

27
EXCLUSION CRITERIA

• Monocular pxs
• Uncontrolled vascular dxs
• Immuno-compromise auto-immune dxs
• Corneal irregularities keratoconus, dystrophies,
  infections (Herpes)
• Pachymetry lt 450?m gt irregular astigmatism,
  distortion, corneal rupture

28
EXCLUSION CRITERIA

• Pregnant/nursing patients gt fluctuation of Vx,
  effects on healing process, cant be put on
  medication
• Active ocular dx eg. Glaucoma, retinal diseases
• Ocular herpes within the last yr
• Progressive myopia
• Dry eyes tear integrity compromised ffg LASIK

29
BASIC LASIK PROCEDURE
2
3
Suction ring applied (65mmHg)
Under L/A, cornea is marked
Microkeratome cut hinged flap
4
5
6
Flap folded to expose stromal bed
Stromal ablated
Flap repositioned
30
POST-OP MX

• antibiotics and corticosteroid therapy(4-6wk
  tapered course), tear supplements
• return 1 day, 1 wk, 3wks, 3 months, 6months
• avoid water in eyes - no shower, hot tub or
  swimming- first 2wks
• wear protective gear in any contact sports
• avoid eye rubbing gt dislocation of flap
• enhancements / retreatment 3-6 mnths later
  adequate stabilization of flap

31
SIDE EFFECTS

• BLURRED VX d/2 haze, oedema, epithelial defects,
  under / overcorrection

Corneal haze
32
SIDE EFFECTS

• OPTICAL ABBERATIONS higher order (prolate to
  oblate shape) gt ghost images, haloes, shadows gt
  decrease optical quality
• DRY EYES d/2
• conjunctival goblet cell damage / disruption of
  feedback loop from lacrimal gland to brainstem
  (neurotrophic theory)
• cut corneal nerves ? sensitivity gt ? CSF and
  optical quality

33
SIDE EFFECTS

• NIGHT Vx PROBLEMS d/2 opt zone diam lt pupil
  diam/ residual Rx / irregular astig gt haloes and
  decr vision. Often require night driving Rx

Haloes
starbursts
34
SIDE EFFECTS

• DISCOMFORT first 24 hrs, but not as painful as
  PRK, d/2 speculum gt orbital ache
• PHOTOPHOBIA related to optical quality and
  scattering, healing or haze
• CONJUNCTIVAL HAEMORHAGE d/2 application of
  suction ring

35
COMPLICATIONS

• Chisholm (2001) 5.3 cases
• INTRAOPERATIVE during surgical procedure eg
  pupil bisection, free flap, loss of corneal flap,
  perforated or thin flap, corneal perforation,
  bleeding of neo vessels
• POSTOPERATIVE following surgical procedure eg.
  displaced flaps, corneal infection, diffuse
  lamellar keratitis (Sands of Sahara), regression

36
POST REFRACTIVE SURGERYCLINCAL IMPLICATIONS FOR
THE OPTOMETRIST

• 1. ? in BCVA CSF
• d/2 higher order aberrations which ? optical
  quality
• Imp with artists, architects, draftsmen who
  require good contrast sensitivity
• Solution
• Expected that Wavefront guided ablations
• targeted beam - sent thro eye - focused on
  retina.
• wave of light rays - reflected back from the
  retina through the eyes lens, pupil and cornea -
  irregularities mxed with sensor
• Using this mxment - used to program the laser
  allows customized reshaping of cornea during the
  LASIK procedure.
• Hannush (2003) vs Phusitphoykai et al. (2003)
  conflicting results

37
POST REFRACTIVE SURGERYCLINCAL IMPLICATIONS FOR
THE OPTOMETRIST

• 2. ? NIGHT VISION
• d/2
• Residual Rx
• Irregular astigm
• Pupil diam gt corrected optic zone diam
• Solution
• Rx for driving
• GP C/L
• Miotic drops
• Wavefront Rx

38
POST REFRACTIVE SURGERYCLINCAL IMPLICATIONS FOR
THE OPTOMETRIST

• 3. UNDERESTIMATION OF IOP
• Appl tono gt underestimates IOP
• d/2
• Flattened and thinned central cornea
• Implication delay diagnosis of glaucoma
• Solution IOPs gt 17mmHG should be investigated
  further

39
POST REFRACTIVE SURGERYCLINCAL IMPLICATIONS FOR
THE OPTOMETRIST

• 4. DRY EYES
• d/2
• conjunctival goblet cell damage
• disruption of feedback loop from lacrimal gland
  to brainstem (neurotrophic theory)
• cut corneal nerves ? sensitivity
• Implications ? optical quality, discomfort
• Solution
• Tear supplements
• Punctal occlusion

40
POST REFRACTIVE SURGERYCLINCAL IMPLICATIONS FOR
THE OPTOMETRIST

• 5. IATROGENIC KERACTASIA
• d/2
• Bowing forward of post cornea thro weakened ant
  cornea
• Implication astigmatism keratoconus
• Solution
• Monitor post-refractive surgery patients closely
  wrt corneal integrity
• GP C/Ls

41
POST REFRACTIVE SURGERYCLINCAL IMPLICATIONS FOR
THE OPTOMETRIST

• 6. SLIT LAMP EXAMINATION
• ASSESS
• Integrity of flap
• Keratitis (Sands of Sahara) refer immediately

42
POST REFRACTIVE SURGERYCLINCAL IMPLICATIONS FOR
THE OPTOMETRIST

• 7. KERATOMETRY AXIAL LENGTH MEASUREMENT
• Accuracy of readings affected by refractive
  surgery
• Imp take these measurements prior to the
  procedure in the event px require IOL later on
  in life

43
POST REFRACTIVE SURGERYCLINCAL IMPLICATIONS FOR
THE OPTOMETRIST

• 8. DONOR CORNEAS
• Post- refractive surgery corneas cannot be used
  for penetrating keratoplasty (corneal
  transplants)
• Concern negative impact on availability of
  donor corneas

44
POST REFRACTIVE SURGERYCLINCAL IMPLICATIONS FOR
THE OPTOMETRIST

• 9. BINOCULAR VX CORRECTION WITH PRISMS
• Pxs using prisms in spectacles prior to
  refractive surgery will require prism spectacles

45
REFRACTIVE SURGERY THE OPTOMETRIST

• Unbiased advise to make an informed decision
• Requires practitioner education and familiarity
  with different aspects of refractive surgery
• interdisciplinary collaboration pre-op, post-op
  management in conjunction with ophthalmologist
• Research long term effects remain unknown ??

46

• THANK YOU FOR YOUR ATTENTION !!