Wavefront-Guided Laser Surgery

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Wavefront-Guided Laser Surgery
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How the eye works

• Light rays enter the eye through the clear
  cornea, pupil and lens.
• These light rays are focused directly onto the
  retina, the light-sensitive tissue lining the
  back of the eye.
• The retina converts light rays into impulses,
  sent through the optic nerve to your brain, where
  they are recognized as images.
• 70 of the eye's focusing power comes from the
  cornea and 30 from the lens.

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Refractive errors

• Inability to see clearly is often caused by
  refractive error.
• Four types of refractive error
• Myopia (nearsightedness)
• Hyperopia (farsightedness)
• Astigmatism
• Presbyopia

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Refractive errors myopia

• In myopia (nearsightedness), there is too much
  optical power in the eye
• The distance between the cornea and the retina
  may be too long or the power of the cornea and
  the lens may be too strong.
• Light rays focus in front of the retina instead
  of on it.
• Close objects will look clear, but distant
  objects will appear blurred.

Myopia, or nearsightedness
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Refractive errors hyperopia

• In hyperopia (farsightedness), there is too
  little optical power.
• The distance between the cornea and the retina
  may be too short.
• Light rays are focused behind the retina instead
  of on it.
• In adults (but not children), distant objects
  will look clear, but close objects will appear
  blurred.

Hyperopia, or farsightedness
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Refractive errors astigmatism

• In astigmatism, the cornea is curved
  unevenlyshaped more like a football than a
  basketball.
• Light passing through the uneven cornea is
  focused in two or more locations.
• Distant and close objects may appear blurry.

Astigmatism occurs when light passes through
football-shaped cornea and/or lens
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Refractive errors presbyopia

• Presbyopia is an age-related condition in which
  your eyes gradually lose the ability to see
  things up close, because the lens of the aging
  eye can no longer change shape.
• When we are young, the lens in our eyes is
  flexible and is able to change focus easily
  between near and far objects, like an autofocus
  on a camera.
• At around age 40, this flexibility begins to
  gradually decrease, making it more difficult to
  see objects up close, unless the eye has
  nearsightedness.

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What is refractive surgery?

• A group of outpatient surgical procedures used to
  alter how your eye focuses light rays on the
  retina, thereby improving vision and reducing
  dependence on glasses and contact lenses.
• In most cases, refractive surgery affects the
  shape of your cornea to redirect how light is
  focused onto the retina. Popular procedures
  include LASIK, LASEK, PRK and CK.

Refractive surgery procedure on the cornea
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What is refractive surgery?

• Most refractive surgery is performed on the
  cornea and affects only the front of your eye,
  while the rest of your eye will change naturally
  as you age.
• In some cases, refractive surgery procedures
  dont reshape the cornea instead, the eyes
  natural lens is either replaced or enhanced by an
  implantable lens that helps correct vision.

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What is Laser In Situ Keratomileusis (LASIK)?

• Outpatient refractive surgery used to treat
  nearsightedness (myopia), farsightedness
  (hyperopia) and astigmatism.
• With LASIK, an excimer laser is used an
  invisible, cold laser capable of sculpting highly
  accurate changes in corneal shape.
• Most common type of refractive surgery procedure.

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How is LASIK performed?

• Your ophthalmologist (Eye M.D.) uses a
  microsurgical instrument (usually a
  microkeratome) to cut a thin, hinged flap of
  corneal tissue.
• Once the flap is lifted to one side, laser energy
  is applied for a few seconds to a minute or so to
  reshape the exposed surface of your cornea.
• The tissue flap from your cornea is placed back
  into its original position, where it adheres
  naturally, protecting the treated area and
  restoring the smooth front surface of your eye.
• After the procedure, the reshaped cornea focuses
  light more accurately on the retina.

With LASIK, laser energy is applied to reshape
the exposed surface of your cornea
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What is wavefront-guided LASIK?

• One of the keys to a successful LASIK procedure
  is the measurement your ophthalmologist takes to
  determine your refractive error.
• Small imperfections in the eye cause some light
  to travel through the eye at different angles,
  causing light to strike the retina in different
  places collectively, these imperfections are
  called optical aberrations.
• Wavefront can be described as a fingerprint of
  your eye the instruments that measure it reveal
  tiny, subtle variations in the way light passes
  through your eye that are as unique as your
  fingerprints.
• Additional subtle measurements of the corneal
  shape itself can be done with a surface
  topographer.

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What is wavefront-guided LASIK?

• Wavefront-guided LASIK uses a measuring device to
  create a map of how your eye focuses light, to
  precisely assess the unique irregularities and
  variations in your eye.
• The wavefront map is very detailed instead of
  creating a general description of your eyes
  focus (for example, nearsighted), it records
  every subtle curve and dip in the focus of your
  eye.

Wavefront technology creates a map of your eye
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What happens during the wavefront measurement?

• Your ophthalmologist maps both of your eyes using
  a wavefront scanner, called an analyzer or
  aberrometer.
• The aberrometer produces a very precise, detailed
  map of light rays as they travel through your
  eye, highlighting imperfections in your vision.
• A targeted beam of light will be sent through
  your eye and focused on the retina.

With wavefront, a targeted beam of light is
focused on the retina
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What happens during the wavefront measurement?

• A wave of light rays is reflected back from the
  retina through the eyes lens, pupil and cornea.

• A sensor will measure the irregularities in the
  wavefront pattern of light as it emerges from
  your eye.

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What happens during the wavefront measurement?

• Using this measurement, the wavefront computer
  creates an accurate, three-dimensional map of the
  light rays created by your eyes optical system.
• This wavefront data will be used to program the
  excimer laser, allowing your ophthalmologist to
  customize the reshaping of your cornea during the
  LASIK procedure.

The wavefront computer creates a
three-dimensional map of your eyes visual system
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What are the benefits of using wavefront
technology?

• Wavefront-guided LASIK reduces the possibility
  that you will have quality-of-vision complaints,
  such as poor night vision, difficulty driving at
  night, glare, halos and blurry images after
  surgery.
• Some optical aberrations can distort your vision
  and cannot be corrected with glasses and
  contacts. They can only be measured with
  wavefront analysis.
• A main difference between conventional LASIK and
  wavefront-guided LASIK is that wavefront-guided
  LASIK reduces the likelihood that aberrations
  will result in quality-of-vision complaints.

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Considerations for wavefront-guided LASIK surgery

• Less invasive procedure than intraocular surgery,
  thus reducing quality-of-vision complaints.
• Wavefront-guided LASIK is most useful for those
  individuals with measurable wavefront
  abnormalities.
• Procedure and recovery is usually painless and
  quick, as in standard LASIK.

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Considerations against wavefront-guided LASIK
surgery

• More corneal tissue is removed with
  wavefront-guided LASIK than in conventional
  LASIK.
• Wavefront-guided LASIK is not currently approved
  for surface procedures, such as PRK.
• Wavefront-guided LASIK is not recommended for
  patients with thin corneas.
• Wavefront-guided LASIK is not recommended for
  patients with keratoconus (irregular protrusion
  of the cornea).
• Wavefront-guided LASIK is not recommended if
  myopia, hyperopia or astigmatism is beyond the
  parameters of the procedure.
• Wavefront-guided LASIK is not recommended for
  patients with significant systemic medical
  illnesses that may severely affect healing.
• Wavefront-guided LASIK is not recommended for
  patients with severe dry eye.
• May be restricted from certain occupations after
  the wavefront-guided LASIK procedure.

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To be a candidate for wavefront-guided LASIK, you
should

• Be over 21 years of age.
• Not be pregnant or nursing.
• Be free of any eye disease.
• Have a stable eye prescription over the past
  year.
• Have a refractive error within the range of
  correction.

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Risks and possible side effects of
wavefront-guided LASIK surgery

• Over-correction or under-correction (with a
  possible need for a re-treatment.
• Reduced contrast vision (sharpness).
• Poor night vision.
• Glare, halos, starburst, ghosting of images.
• Corneal infection.

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Risks and possible side effects of
wavefront-guided LASIK surgery

• Light sensitivity.
• Dry eyes.
• Flap complication (either during or following
  surgery).
• Loss of vision.
• Regression of initial surgical effect.

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Is refractive surgery right for you?

• Advanced surgical procedures, including
  wavefront-guided laser surgery, are creating more
  opportunities for people who want to be less
  dependent on glasses or contacts.
• Other surgical procedures include LASEK, PRK,
  phakic and accommodative IOLs.
• Surgery may not entirely eliminate your need for
  corrective lenses. Glasses/contacts may still be
  needed for activities such as fine or detailed
  work, reading and perhaps night driving.

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Is refractive surgery right for you?

• A large part of the success of any refractive
  surgery depends on your understanding of the
  procedure and your expectations.
• Since refractive surgery is an elective
  procedure, you have the opportunity and
  responsibility to become fully informed about its
  risks and benefits.
• Your ophthalmologist will explain the specific
  technique, its benefits, as well as possible
  risks and side effects associated with your case.

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Discuss options and questions with your
ophthalmologist

• With the help of your ophthalmologist, its
  ultimately your responsibility to weigh the risks
  and side effects of a procedure with the benefits
  it has to offer.
• If you decide refractive surgery is right for
  you, you may join millions of people who have
  reduced their dependence on glasses or contacts.