EVOLUTION OF REFRACTIVE SURGERY

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EVOLUTION OF REFRACTIVE SURGERY
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Types of Refractive Surgery

• Incisional - RK, AK, ALK
• Laser - PRK, LASIK, LASEK, Epi LASIK
• Corneal - Intacs
• Intraocular - Refractive Lensectomy, Phakic IOLs,
  etc.

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Evolution of Refractive Surgery
Corneal Inlays
RK
PRK
LASIK
Most Recent Advances CK- Conductive
Keratoplasty CustomLASIK- Wavefront Guided Laser
Ablation Refractive Intraocular Lenses Epi
LASIK Multifocal Ablations
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Incisional/Ablative Procedures
PRK
LASIK
RK
Permanent alterations to Central Optical Zone
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Incisional Refractive Procedures

• Radial Keratotomy / Astigmatic Keratotomy
• Oldest of elective refractive procedures
• Popular during 1980s
• Some resurgence just before Laser approved
• Problems
• Weakens Globe
• Many side effects long term fluctuation of
  vision, halos, glare, progression of effect
• Limited Application low to moderate myopia and
  astigmatism

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RK - RADIAL KERATOTOMY
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RK - RADIAL KERATOTOMY
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TOO MUCH RK
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MYOPIC KERATOMILEUSIS

• MKM - Myopic Keratomileusis - used a
  microkeratome to resect a thick corneal cap which
  was frozen, lathed, and sutured onto the cornea

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Incisional Refractive Procedures

• Automated Lamellar Keratoplasty
• Could treat both myopia and hyperopia
• Required a microkeratome to create a corneal flap
  and, when correcting myopia, to remove a small
  disk of corneal tissue
• Predecessor to LASIK

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ALK - AUTOMATED LAMELLAR KERATOPLASTY

• Use of ACS (Automated Corneal Shaper) to remove a
  thin resection of tissue causing central
  flattening for treatment of myopia.

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ALK Advantages Over Previous Procedures

• Treat high degrees of myopia as well as low
  amounts of hyperopia
• Get a patient in the range of RK
• Healing advantages
• Rapid vision rehabilitation
• Minimal healing influences
• Minimal discomfort

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Ablative Refractive Procedures

• Photorefractive Keratectomy (PRK)
• First refractive procedure to use the excimer
  laser
• Can treat myopia, hyperopia and astigmatism
• Patient can have significant discomfort in early
  postop period due to removal of epithelium
• Slow visual recovery
• Patients normally treated one eye at a time
• Mitomycin C sometimes used to lessen haze/scarring

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PRK Procedure
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PRK For Treatment of Myopia
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PRK Advantages Over Previous Procedures

• Increased Accuracy over MKM
• Reduced Surgical Learning Curve
• Practitioner Friendly

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Disadvantages of PRK

• Mild Discomfort
• Increased time to best uncorrected vision
• Outcome is not completely predictable
• Possible Under or Overcorrection
• Could result in a retreatment or enhancement
• Possible corneal haze effecting vision

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Combination Incisional Ablative Procedure

• Laser In Situ Keratomileusis - LASIK
• Uses a flap maker to create a protective flap of
  corneal tissue and the excimer laser to treat the
  refractive error
• Combined the accuracy of the laser with the
  quicker visual recovery of ALK

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LASIK
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LASIK
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ADVANTAGES OF LASIK OVER PRK

• Bilateral Friendly
• Many PRK Healing Risks Avoided
• Less, but more rapid regression
• Stable results
• Patient friendly

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Disadvantages of LASIK

• Intraoperative flap complications
• Incomplete flaps or caps
• Postoperative flap complications
• Striae (wrinkles in the flap)
• Ingrowth
• Diffused Lamellar Keratitis (DLK or Sands)
• Possible Over or Undercorrection
• Enhancement for residual refractive error

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Clear enough? ONE DAY!
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LASEKLaser Epithelial Keratomileusis

• Similar to PRK
• Epithelial flap is created either mechanically or
  manually and moved to expose the stroma for laser
  treatment and then repositioned
• Potential less pain than PRK.
• Alternative for patients with large pupils thin
  corneas.

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LASEK

• Thinner flap consisting of the Epithelium Layer
  only
• How thick is the Epithelium?
• Less chance of Ectasia (thinning of the cornea)
• More dependence of healing
• Comfort of LASIK Safety of PRK

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Epi LASIK

• Very similar to LASEK
• Mechanical device used to create Epi Flap
• Cleaves or separates Epithelium from Bowmans
  Membrane
• Delicate, thin flap

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Corneal Inlays Intacs?

• Treats low amounts of myopia and keratoectasia
• Two arch shaped inlays surgically placed in
  periphery of cornea, outside the optical zone for
  refractive procedures
• Seldom used technology for refractive surgery,
  but being revisited for Niche procedures in
  Keratoectasia treatment

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LTK- Laser Thermal Keratoplasty

• HolmiumYAG Laser (Sunrise)
• Circular pattern of small thermal spot treatments
  to steepen the central cornea.
• Designed for Hyperopia.
• Limited treatment range.
• Temporary Affect

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Conductive Keratoplasty - CK

• Circular Zones of small radio wave spot
  treatments to steepen the central cornea
• Approved for Hyperopia and Presbyopia
• Limited Range of correction and control
• Unplanned Benefit of Multi-focality
• Presbyopic positive side-effect

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SCLERAL EXPANSION BANDS

• Designed to treat presbyopia
• Not FDA approved
• Theory presbyopia is due to slackening of fibers
  attached to the lens.
• Above Implanted scleral expansion band (full
  circular band model)
• Below Scleral expansion bands compared with a
  penny (band segment model)

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CustomLASIK

• A.K.A WaveFront Guided Laser Ablation
• Wavefront Aberrometer Required.
• Correct Sphere and Cylinder and small
  imperfections (High Order Aberrations)
• Improved Visual Quality (less halos and glare.)
• Improved Night Vision.

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REFRACTIVE LENSECTOMY

• Alternative for patients not qualified for cornea
  refractive procedures or patient with early
  lenticular changes
• Similar to cataract surgery natural lens is
  removed artificial lens is implanted.
• Instant Presbyopia
• Accomodating IOLs
• possibility to retain near vision

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PSEUDOPHAKIC INTRAOCULAR LENSES THAT MAINTAIN
ACCOMMODATION

• Alternative for patients not qualified
  for corneal refractive procedures or have
  existing cataracts.
• Permanent implant inside the eye.
• Replaces natural lenses
• Pt retains accommodation through special
  hinges

Example Crystalens
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PHAKIC INTRAOCULAR LENSES

• Alternative for patients not qualified for
  corneal refractive procedures
• Permanent implant inside the eye.
• Can be positioned in the anterior chamber or
  posterior chamber in front of the natural lens.
• Pt retains accommodation

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Summary

• LASIK is the dominant corneal refractive
  procedure
• The key to ultimate patient care is knowing
  advantages/disadvantages of each option