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Medically reviewed by Last updated on Jun 5, 2023.

What is LASIK?

Harvard Health Publishing

LASIK is a form of eye surgery that uses a laser to reshape the cornea. LASIK stands for "laser in situ keratomileusis."

The cornea is the clear, round "window" of tissue that allows light to enter the front of the eye. By reshaping the cornea, the surgeon adjusts the focus of light on the retina. (The retina is the layer at the back of the eye responsible for sight.)

LASIK surgery often improves vision in people who have nearsightedness, farsightedness or certain other vision problems.

In LASIK, the eye surgeon first cuts a small, hinged flap of tissue from the front of the cornea. This is done with an instrument called a microkeratome. Once this flap is moved out of the way, a laser is used to reshape the underlying protein fibers (collagen) of the cornea.

This reshaping is based on precise measurements made by the eye doctor during the presurgery exam. When the laser reshaping is done, the corneal flap is moved back into place.

The cornea heals quickly. As a result, many people who have LASIK surgery notice dramatic improvements in vision almost immediately.


LASIK is an outpatient procedure. This means there is no overnight stay in a hospital. Typically eye surgeons work on both the right and left eyes at one sitting. It generally takes 10 to 15 minutes for each eye.

LASIK is the most common surgical treatment to correct nearsightedness in the United States. The technique has been used successfully in the U.S. since 1991.

In addition, most health insurance policies do not cover LASIK surgery. People must pay the entire cost of the procedure themselves.

What It's Used For

LASIK can be used to treat the following vision problems:

If you have one of these vision problems, your eye doctor can help determine whether LASIK surgery is appropriate for you.

LASIK may not be an option for you if:


Once you decide to have LASIK eye surgery, your doctor will schedule an eye evaluation prior to surgery. If you wear contact lenses, you must switch to eyeglasses for a few weeks before this evaluation. This will allow your cornea to resume its natural shape.

At your presurgery eye evaluation, your eye doctor will review your medical history and eye history. To confirm that your vision is stable, he or she may ask to see your eye prescription records. Bring those with you to the examination.

Also, make a list of any medications you take. The list should include any over-the-counter drugs and herbal remedies. Your doctor will need to review this list.

After using eye drops to widen (dilate) your pupils, the doctor will examine your eyes thoroughly. This examination will include:

Your doctor will take precise measurements of your eyes. These will include measurements of the shape and thickness of your cornea.

After this eye examination is finished, your doctor will discuss LASIK as an option for you. This discussion should include:

At the end of this discussion, your doctor probably will ask to you sign an informed consent form. This gives the doctor permission to do the surgery.

How It's Done

Your doctor will ask you to stop wearing makeup, lotions and perfumes for a day or two before surgery. You will not be able to drive after your LASIK procedure. Make arrangements for someone to drive you home.

On the day of the procedure, your doctor may give you a mild sedative to help you relax. You will enter the operating room and lie down in a reclining chair.

The area around your eye will be cleaned with an antiseptic solution. Next, numbing eye drops will be placed in your eye so that you will not feel pain or discomfort during the procedure. An instrument called a lid speculum will be inserted into your eye to keep your eyelids open. The doctor will use special ink to mark the surgical area on your cornea.

Next, a ringlike suction device will be placed on the front of your eyes to hold your cornea in place during the procedure. This suction ring will cause a sensation of pressure, but no pain.

Then, a delicate cutting instrument called a microkeratome or a special cutting laser will be used to slice a tiny, hinged flap of tissue from the front of your cornea. You will not see or feel the microkeratome cutting your cornea.

Once the cutting is done, the surgeon will remove the suction ring from your eye, and fold back the hinged flap of cornea. Next, the laser will be moved into position, and you will be asked to stare at a light. Staring fixes your gaze and keeps your eye from moving.

Once your eye is steady, the doctor will use the laser to vaporize portions of your cornea. This vaporization is guided by a computer. It is based on precise eye measurements that were made during your presurgery examination. As the laser works, you will hear a clicking sound, and you may notice a smell similar to burning hair. These sounds and smells are normal.

When your laser treatment is finished, the doctor will reposition the hinged flap of cornea. No stitches are necessary. The doctor probably will cover your eye with an eye shield to protect the corneal flap as it heals.

You will be prescribed eye drops, which often include a topical corticosteroid and antibiotic. You likely will need someone to help you with the drops when you first get home. It’s important to strictly follow your doctor’s instructions.

After your surgery, you must be careful not to touch or press your eye. For a day or two, the pain can be intense. Your doctor will provide information to help with pain relief.


Your first follow up visit probably will be scheduled for the day after surgery. At this visit, your doctor will:

He or she may prescribe antibiotic eye drops and "artificial tears."

Your doctor will tell you when it is safe for you to resume:

To help protect your healing eye, you probably will need to wear the eye shield at night for about four weeks.

Your doctor may ask you to return for a second follow up visit seven days after surgery. Depending on your progress, a few more eye exams may be necessary in the next six months.


Potential risks and complications include:

Surgical complications occur in a small number of LASIK patients. In addition, some people develop complications within the first three months after surgery. About 10 percent of patients need to return for a second procedure to fine tune vision.

For the majority of people, however, LASIK treatment is successful and uncomplicated. Nearsighted patients usually achieve vision that measures 20/40 or better after LASIK surgery. For farsighted patients, the percentage is somewhat lower, but still quite high. In some cases, vision improves immediately. In others, improvement occurs gradually over three to six months.

When To Call A Professional

Call your doctor immediately if:

Additional Info

National Eye Institute

American Society of Cataract and Refractive Surgery


Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.