LASIK eye surgery

Definition

LASIK is eye surgery that permanently changes the shape of the cornea (the clear covering on the front of the eye). It is done to improve vision and reduce a person's need for glasses or contact lenses.

Alternative Names

Laser-Assisted In Situ Keratomileusis; Laser vision correction; Nearsightedness - Lasik; Myopia - Lasik

Description

For clear vision, the eye's cornea and lens must bend (refract) light rays properly. This allows images to be focused on the retina. Otherwise, the images will be blurry.

This blurriness is referred to as a "refractive error." It is caused by a difference between the shape of the cornea (curvature) and the length of the eye.

LASIK uses an excimer laser (an ultraviolet laser) to remove a thin layer of corneal tissue. This gives the cornea a new shape so that light rays are focused clearly on the retina. LASIK causes the cornea to be thinner.

LASIK is an outpatient surgical procedure. It will take 10 to 15 minutes to perform for each eye.

The only anesthetic used is eye drops that numb the surface of the eye. The procedure is done when you are awake, but you will get medicine to help you relax. LASIK may be done on one or both eyes during the same session.

To do the procedure, a flap of corneal tissue is created. This flap is then peeled back so that the excimer laser can reshape the corneal tissue underneath. A hinge on the flap prevents it from being completely separated from the cornea.

When LASIK was first done, a special automated knife (a microkeratome) was used to cut the flap. Now a more common and safer method is to use a different type of laser (femtosecond) to create the corneal flap.

The amount of tissue the laser will remove is calculated ahead of time. Once the reshaping is done, the surgeon replaces and secures the flap. No stitches are needed. The cornea will naturally hold the flap in place.

Why the Procedure Is Performed

LASIK is most often done on people who use glasses or contact lenses because of nearsightedness (myopia). It is sometimes used to correct farsightedness. It may also correct astigmatism.

The FDA and American Academy of Ophthalmology have developed guidelines for determining LASIK candidates.

Other recommendations:

For people with presbyopia, LASIK cannot correct vision so that one eye can see at both distance and near. However, LASIK can be done to allow one eye to see near and the other far. This is called "monovision." If you can adjust to this correction, it may eliminate or reduce your need for reading glasses.

In some instances, surgery on only one eye is required. If your doctor thinks you're a candidate, ask about the pros and cons.

Risks

You should not have this procedure if you are pregnant or breastfeeding, because these conditions can affect eye measurements.

You should not have this procedure if you take certain prescription drugs, such as Accutane, Cardarone, Imitrex, or oral prednisone.

Risks may include:

Before the Procedure

A complete eye exam will be done before surgery to make sure your eyes are healthy. Other tests will be done to measure the curvature of the cornea, the size of the pupils in light and dark, the eyes' refractive error, and the thickness of the cornea (to make sure you will have enough corneal tissue left after surgery).

You will sign a consent form before the procedure. This form confirms that you know the procedure's risks, benefits, alternative options, and possible complications.

After the Procedure

Following the surgery:

Call the eye doctor right away if you have severe pain or any of the symptoms get worse before your scheduled follow-up appointment (24 to 48 hours after surgery).

At the first visit after the surgery, the eye shield will be removed and the doctor will examine your eye and test your vision. You will receive eye drops to help prevent infection and inflammation.

Do not drive until your vision has improved enough to safely do so. Other things to avoid include:

The health care provider will give you specific instructions.

Outlook (Prognosis)

Most people's vision will stabilize in a few days after surgery, but for some people it may take up to 3 to 6 months.

A small number of people may need to have another surgery because the vision is over- or under-corrected. Sometimes, you will still need to wear contact lenses or glasses.

Some people need a second surgery to get the best possible results. Although a second surgery may improve distance vision, it may not relieve other symptoms, such as glare, halos, or problems with night driving. These are common complaints following LASIK surgery, especially when an older method is used. These problems will go away by 6 months after the surgery in most cases. However, a small number of people may continue to have problems with glare.

If your distance vision has been corrected with LASIK, it is likely that you will still need reading glasses at around age 45.

LASIK has commonly been performed in the United States since 1996. Most people seem to have stable and lasting vision improvement.

References

Alio JL, Azar DT, Stasi K, Soria FA. Surgical correction of presbyopia. In: Yanoff M, Duker JS, eds. Ophthalmology. 4th ed. Philadelphia, PA: Elsevier; 2014:chap 3.10.

Garg S, McColgin AZ, Steinert RF. LASIK. In: Tasman W, Jaeger EA, eds. Duane's Clinical Ophthalmology. 2013 ed. Philadelphia, PA: Lippincott, Williams & Wilkins; 2013:vol 6, chap 49.

Sierra PB, Hardten DR, Davis EA. LASIK. In: Yanoff M, Duker JS, eds. Ophthalmology. 4th ed. Philadelphia, PA: Elsevier; 2014:chap 3.5.

Yanoff M, Cameron D. Diseases of the visual system. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine. 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 423.