How does Laser Vision Correction Work?

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  • Written By: Adam Hill
  • Edited By: Bronwyn Harris
  • Last Modified Date: 06 January 2020
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Laser vision correction is a form of laser surgery performed on the eyes in order to correct vision problems such as farsightedness, nearsightedness, and astigmatism. During the procedure, a specially trained ophthalmologist uses a laser to reshape the cornea of the eye. To be a candidate for laser vision correction, you must be at least 18 years of age, have good health and no eye diseases such as cataracts or optic nerve diseases.

When laser vision correction is performed, the surgeon anesthetizes the eyes and may give the patient a mild oral sedative as well. The patient then lies down with one eye positioned directly under the laser device. During the course of the procedure, the eyelids are held open and the eye is pressurized to allow the doctor to more easily perform the required incisions. This is not normally uncomfortable, because of the anesthetic drops used to numb the eyes.

Only one eye at a time is operated on, although both may be done on the same day, if the patient desires. The first incision made is one which creates a tiny flap out of the surface of the cornea. This can be done using a precision instrument called a microkeratome or with a laser. The circular flap is gently folded out of the way, after which the doctor uses the laser to remove tiny amounts of corneal tissue in a process known as ablation.


The laser itself is a concentrated beam of cool ultraviolet light. It is precise enough that it can cut notches in a single strand of hair without breaking it. Each pulse of the laser removes 39 millionths of an inch (99 millionths of a centimeter) of corneal tissue in 12 billionths of a second. When the required corrections have been made, the flap is laid back into place, covering the area where tissue was removed.

When the cornea is reshaped in the correct way, it will be able to focus light directly onto the retina without distortion, ideally solving poor vision. Laser vision correction usually only takes about five minutes to perform. It is best for the patient to bring someone to drive him home afterward, since a few days of rest are required for the eye to heal. Many people notice improved vision immediately, while the vision of others improves over the course of days or weeks.

It is possible that laser vision correction will not give the patient perfectly clear vision. In these cases, any problems are usually very mild, but a few experience significant side effects. There is risk involved with laser vision correction, as with any surgery, and a thorough consultation with an eye care professional is the best way to determine if you are a candidate for the procedure.



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