What is LASIK Eye Surgery?

Lasik is the user-friendly name for Laser-Assisted In-Situ Keratomileusis. As the most common laser eye surgery used to correct refractive errors many people think this is the only procedure used.

It’s often confused with Lasek, which is a modification of PRK. Other laser eye surgery procedures include CK, PresbyLASIK, and Epi-Lasik. Each has unique features that were designed to overcome shortcomings of previous procedures.

Refractive errors result from variations in the curve of the cornea. These errors bend the light too much or too little so that it doesn’t land squarely on the retina.

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The result is blurry vision at one or more distance ranges. You’ll probably know these ranges as nearsightedness and farsightedness.

The most common refractive error is astigmatism. Oddly, people seem to know less about astigmatism than any of the other refractive errors. Astigmatism results from corneas that are oval shaped (often referred to as football shaped.)

Presbyopia is a refractive error caused by the hardening of the natural crystalline lens. As people get older the lens loses flexibility. Its ability to bend enough to focus light for clear vision decreases with age.

The procedure’s unique features involve cutting a flap of tissue that remains attached, performing the corneal ablation on the exposed tissue, then replacing the flap.

Lasik is classified as a surface ablation procedure and combines some of the techniques used in PRK. The major difference is that with Lasik the epithelium is laid back in flaps exposing the cornea during surgery.

It is laid back in place after the surgery. The epithelium is not destroyed in the this procedure as it is in PRK. Earlier procedures used a microkeratome knife to cut the flaps, but newer technology makes it possible to cut these flaps with the laser.

Variations of the procedure include:

  • IntraLASIK – All-laser-Lasik, meaning that the corneal flap is cut with a laser rather than a microkeratome knife.
  • Monovision Lasik – One eye is shaped for best distance vision and the other is shaped for best near vision.
  • Custom Wavefront – Lasik that is highly customized to each eye using a Wavefront guided laser beam to ablate the cornea. Wavefront technology is also used to obtain diagnostic measurements in the first of two steps. These measurements are used in the second step, the Lasik (ablation) procedure to sculpt the most effective shape for each cornea.
  • How Does It Work?

    This procedure is done on an outpatient basis. One or both eyes might be corrected in the same day. This is something you will decide with your eye surgeon during your examination, diagnosis and planning for surgery.

    During this phase you might undergo diagnosis using Wavefront Technology, which will measure the refractive error for each eye, and computerize the results. This data can also be used to control the excimer laser during ablation.

    You might be given a mild sedative before surgery, but expect to be awake during this very short procedure. Your eye surgeon will numb your eye, then cut the epithelial flap and lift it back.

    With the corneal tissues exposed the eye surgeon can reshape it with the laser. It takes only a minute or two to complete the ablation.

    The flap is placed back over the cornea where it will reattach itself as part of your healing. You will spend a short time in recovery before either having your other eye treated, or going home.

    One of the advantages of this surgery over PRK and other procedures is the absence of pain. Most people describe it as mild discomfort. While most people feel little or no pain after surgery, your surgeon will prescribe pain meds if you need them.

    Occasionally, patients experience a reversal of improvement after surgery and vision begins to get worse.

    If you are one of the less than 3% who experience a less than satisfactory outcome, speak to your surgeon about a follow-up enhancement. Most problems are correctable with a follow-up treatment. There are no reported cases causing blindness.

    Pros and Cons

    The epithelial tissue is retained in Lasik procedures. Because of this:

  • Recovery time is 2 days to 1 week, faster than Lasek or PRK.
  • There is usually less discomfort than PRK or Lasek – almost no pain.
  • Vision improves faster than PRK or Lasek, often almost immediately.
  • You can drive 1 to 3 days after surgery.
  • You can usually return to work the next day.
  • Most people achieve 20/20 or better vision.
  • Corneal haze is very rare.
  • Outcomes are more predictable and stable than with PRK.
  • You can expect clearer corneas than with PRK.
  • Follow-up enhancements are easier when needed.
  • Wavefront Lasik can worsen higher order aberrations.
  • Flaps can dislodge if eyes are hit after surgery.
  • Flaps created with a blade can create uneven edges leading to astigmatism.
  • Indicated If You:

  • have sufficient corneal tissue to do the procedure
  • are at least 18 years of age
  • have nearsightedness, farsightedness, presbyopia or astigmatism correctable by laser eye surgery
  • have no eye disease or condition that can interfere with healing
  • have a corneal shape within treatable range
  • have normal pupil size
  • have adequate tearing, moisture
  • are otherwise a qualified candidate for Lasik eye surgery
  • Contra-Indicated If You:

  • have thin corneas
  • engage in hobbies or professional activities that are rough or pose risk of hitting eyes
  • have dry eye – Lasik can worsen dry eye, and may even cause it.
  • have had substantial lens prescription changes within two years
  • have cataracts
  • have glaucoma
  • are pregnant or nursing (lactating)
  • have corneal scarring
  • are taking steroids or immunosuppressants
  • have eye disease or abnormalities that will slow healing such as:
  • diabetic retinopathy
  • ocular hypertension
  • autoimmune disorders
  • Herpes simplex of the eye
  • hypertension
  • Associated Risks :

    Lasik eye surgery risks are similar to those of other laser eye surgery procedures. Though rare, the ones that occur most often include:

  • over- or under-corrections
  • halos or starbursts around lights
  • erosion of the epithelium
  • dry eye
  • infection
  • corneal scarring
  • eyelid droop
  • chronic discomfort
  • inability to tolerate contact lenses

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