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When light enters a medium that causes it to change speed it also changes direction.

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Laser Eyes

Laser Eyes


Credit: United States, National Institutes of Health, National Eye Institute
Source: http://commons.wikimedia.org/wiki/File:Diabetic_retinopathy_laser_surgery-NEI.jpg
License: CC BY-NC 3.0

The beam of red light focusing on this patient’s eye is laser light. A laser is an optical instrument that produces such intense light that it can be used for cutting. A type of eye surgery, called Lasik surgery, uses lasers to cut eye tissue.

The Back Story

  • Each year, more than 600,000 patients have Lasik eye surgery in the U.S. alone. The surgery is used to correct vision problems. It can correct nearsightedness, farsightedness, and astigmatism.
  • Lasik surgery works by cutting, and permanently changing the shape of, the cornea of the eye. It often results in 20-20 vision. Usually, patients who previously needed lenses to correct their vision no longer need them after the surgery.
  • Credit: Peretz Partensky
    Source: http://www.flickr.com/photos/ifl/6327626512/
    License: CC BY-NC 3.0

    Lasik is still a type of surgery, and requires anesthetics to dull the pain [Figure2]

  • To see how Lasik surgery is done and why it works, watch the following brief slide show and very short video:

Show What You Know

Learn more about Lasik surgery at the link below. Then answer the questions that follow.

  1. What is the cornea? What is its role in vision?
  2. Outline the steps involved in Lasik surgery.
  3. How is the cornea reshaped during Lasik surgery? How does this improve vision?
  4. What are some possible risks of Lasik surgery?

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Image Attributions

  1. [1]^ Credit: United States, National Institutes of Health, National Eye Institute; Source: http://commons.wikimedia.org/wiki/File:Diabetic_retinopathy_laser_surgery-NEI.jpg; License: CC BY-NC 3.0
  2. [2]^ Credit: Peretz Partensky; Source: http://www.flickr.com/photos/ifl/6327626512/; License: CC BY-NC 3.0

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