The thought of living without glasses or contacts is apparently appealing to the estimated 600,000 people a year who get Laser-Assisted In Situ Keratomileusis, or LASIK. This refractive eye surgery changes the shape of the cornea and thus helps improve vision. The majority of people who get LASIK are happy with the surgery and after surgery, are able to see clearly without being fettered by prescription glasses or contact lenses.

However like any surgery, LASIK does pose risks, and any decision to electively undergo LASIK surgery must be carefully considered and discussed with your ophthalmologist, or eye physician. In other words, undesirable things can happen after LASIK.

LASIK Basics

You’ve probably heard of LASIK, but you may be unsure exactly how it works. 

The surface layer of your eye is called the cornea. When the cornea is deformed, light isn’t properly refracted, or focused, onto your retina, and it’s harder to see. With LASIK, a laser or blade is used to cut a flap in your cornea. and then a laser is used to reshape your cornea before the flap is replaced. Thus, because the shape of the cornea is changed, light should be better focused on your retina.

The FDA has approved LASIK for the following three conditions:

Myopia (nearsightedness) Hyperopia (farsightedness) Astigmatism (the curvature of the cornea resembles a football rather than a basketball)

Avoid LASIK

Please keep in mind that before you receive LASIK, your ophthalmologist should perform a comprehensive visual exam.

Not everyone is a good candidate for LASIK. The following is a list of conditions that discount people as candidates for this procedure:

History of eye disease, such as glaucoma or herpesHistory of eye injury or surgeryDry eyes (sicca), as occurs with Sjogren’s syndromeThin corneasLarge pupilsDiabetesAutoimmune diseases, like rheumatoid arthritisImmune compromise (think HIV/AIDS)Ectasia, or bulging of the cornea, which occurs with keratoconusUse of corticosteroids, which deter wound healingRecent changes in your contact lens or glasses prescriptionSome cases of age-related changes to the eye like presbyopiaVery large refractive errors

Finally, if you have relatively good vision to begin with, you shouldn’t get LASIK.

Adverse Effects of LASIK

When LASIK is done properly, the benefits outweigh the risks for most patients. Nevertheless, negative outcomes do occur even in people who are good initial candidates.

Here are some adverse effects of LASIK that are usually mild and transient:

Dry eyes Blurred vision Halos Sensitivity to light Starbursts Double vision Impaired night vision 

Please note that in a minority of people, these symptoms can become permanent and problematic.

Here are some more severe adverse effects of LASIK:

Vision lossInfectionEctasiaOvercorrectionUndercorrection

LASIK doesn’t always lead to perfect (20/20) vision, and you may still need to wear glasses to read and so forth. In particular, if you have age-related presbyopia or farsightedness that occurs in middle or older age due to decreased elasticity of the lens, you’ll still need to wear bifocals. Sometimes people need more than one surgery after LASIK to correct their vision.

When choosing an ophthalmologist to perform your LASIK eye surgery, please do your research. First, find out about the devices used during your surgery and whether some other refractive surgery, like LASEK, would better benefit you. Second, make sure that the ophthalmologist whom you choose has plenty of experience. Third, be wary of bargain LASIK procedures or phony promises that guarantee you perfect vision or your money back.