Understanding LASIK

Laser In Situ Keratomileusis (LASIK) is a surgical procedure that uses a laser to reshape the curvature of the cornea. It treats vision problems caused by refractive errors, such as myopia (nearsightedness), hyperopia (farsightedness) and astigmatism.

For you to see clearly, light rays must travel through your cornea and lens. The cornea and lens refract the light so it lands on the retina. The retina turns light into signals that travel to your brain and become images. With refractive errors, the shape of your cornea or lens keeps light from bending properly. When light is not focused on the retina as it should be, your vision is blurry.

The goal of LASIK is to correct your refractive error to help reduce your dependence on eyeglasses and/or contact lenses. About 9 out of 10 people (90%) who have LASIK end up with vision between 20/20 and 20/40, without corrective lenses. However, you might need to wear glasses for certain activities, such as reading or driving at night.


To have LASIK surgery, you need to meet certain requirements:

  • You must be at least 21 years of age.
  • You must have a stable eyeglass prescription for at least 12 months.
  • Your cornea (the tissue on which the laser is done) must be healthy and thick enough for the procedure
  • Certain medical conditions and medications may disqualify you as a candidate
  • You are not pregnant or nursing
  • Your ophthalmologist can talk with you about other conditions that may keep you from having LASIK.

    To determine whether you are a candidate for LASIK, your ophthalmologist will thoroughly examine your eyes during your visit.

    What are the risks of LASIK?

    Like any surgery, LASIK carries risks of problems or complications you should consider.

    Some people have side effects after LASIK that usually go away over time. However, in rare cases, they may not go away. For example, almost everyone who has LASIK will have dry eyes and changing vision during the day. These symptoms usually fade within a month. For some people, though, they may take longer to disappear or they may remain.

    Other side effects, either temporary or permanent, could include:

  • Eye pain or discomfort
  • Hazy, foggy or blurry vision
  • Scratchy eyes
  • Glare
  • Halos (rings) or starbursts around lights
  • Light sensitivity
  • Small pink or red patches or blood on the white of the eye that go away over time
  • Other rare risks include:

  • Eye infection
  • Worse vision than before LASIK, even with glasses or contacts (called loss of best-corrected vision)
  • Blindness
  • Also, with LASIK, your vision may end up being under corrected or overcorrected. These problems often can be improved with glasses, contact lenses or additional laser surgery.

    If you are happy wearing contacts or glasses, you may not want to have refractive surgery. Together, you and your ophthalmologist can weigh the risks and rewards of LASIK.