LASIK Eye Surgery - What it Is; What to Expect

LASIK (laser-assisted in situ keratomileusis) is a type of refractive surgical procedure commonly used to correct a variety of vision disorders, including myopia, hyperopia and astigmatism. One of several types of refractive surgeries, LASIK surgery is currently preferred over other types because of reduced recovery time and pain for the patient.

How LASIK works:
A portion of the cornea is cut into a flap to expose the corneal tissue (or stromal layer) below, which the surgeon reshapes with an excimer laser. People with nearsightedness (myopia), the too-steep cornea is made more flat; for farsightedness (hyperopia), the too-flat cornea is made more steep. Astigmatism can also be corrected by smoothing out an irregularly-shaped cornea.

An instrument called a microkeratome is used to slice a very thin circular flap in the eye's cornea. It is a partial cut, so the surgeon can accurately replace it after surgery. The flap can also be made with a laser. The flap is folded back out of the way, then a portion of the corneal tissue (or stromal layer) underneath the flap is removed with an excimer laser. The excimer laser emits a cool ultraviolet beam to remove very small, precise amounts of corneal tissue. The type of correction needed for each eye determines exactly where tissue is removed. After shaping, the surgeon carefully replaces the flap of cornea and the surgery is complete. Most patients are able to see more clearly right after surgery.

When done properly, light entering the cornea is focused in the correct place on the retina, creating clearer vision than before.

Considering LASIK?
There are several things to consider before choosing LASIK surgery. First, you'll need to see an optometrist to determine if you're a good candidate for LASIK surgery. The doctor will examine your eyes for overall health, determine what kind of correction is needed and how much cornea should be removed (ablation). If there is any disease present, such as dry eye, this must be corrected before LASIK surgery can be performed.

When you are judged to be a good candidate, the next step is finding a reputable surgeon. Do not allow money to be the main consideration when thinking about LASIK surgery. Finding a surgeon with plenty of experience should take priority over cutting costs. You will need to schedule a pre-op exam before your surgery, where he or she will go over the results of your visit with the optometrist and perform further testing. Generally, the consultation and pre-op exam is done some days in advance of the actual surgery. This gives you, the patient, time to review what you and your doctor have discussed and decide for yourself if LASIK surgery is right for you.

Accurate measuring is important before and during the LASIK surgery. The surgeon may use any of several instruments to measure your eyes. A keratometer is used to measure the curvature of the corneas of the eyes. Intraocular pressure is measured with a tonometer. The doctor may also use a device called a corneal topographer to accurately map the surface of each eye. If you are a good candidate and opt for custom LASIK, which uses new wavefront technology for very complicated corrections, you will need to undergo wavefront analysis, a procedure using a machine that emits waves of light through the eye for an extremely precise map of the irregularities of each eye.

Finally, any health issues you might have or medications that you take may affect whether or not LASIK is right for you. Certain medical conditions such as type-1 diabetes, rheumatoid arthritis or AIDS prevent proper immune function and healing, and make LASIK surgery quite risky. Also, if you are pregnant, fluctuations in hormone levels can actually alter the shape of your eyes.

This is the time to ask questions. Try to prepare a list of questions in advance, and include in your discussion with the doctor your expectations to determine if they are reasonable. Your doctor will discuss the benefits and risks, as well as any alternative procedures you might want to consider. If you agree to proceed with the surgery, you will be asked to fill out a consent form and any other documents the office needs before the actual surgery is performed.

Pre-Op
Preparing for LASIK surgery will take a certain degree of determination on your part. If you wear soft contact lenses, you will need to stop wearing them for several days prior to the surgery - in some cases up to 3 weeks. For hard lens wearers, some experts recommend non-use for up to 6 weeks. Find out what your surgeon recommends. You may also receive instructions on what to do the day before and the day of the surgery and follow the directions given to you exactly.

Make arrangements to have someone drive you to and from the surgery center. You will not be allowed to operate a motor vehicle until after the first post-op exam, usually the day after the surgery, but be prepared to wait a few days after the surgery before being allowed to drive.

The Day of Surgery
It's likely that your surgeon will advise you of things you should do either the day before or the day of the surgery, just prior to arrival at the surgery center. Typically, you should avoid the use of any creams, lotions, cosmetics or perfumes. You may also be asked to scrub the eyelid area prior to arrival to the surgery center. Cosmetics can build up on the skin of the eyelid and increase the chance of infection; some lotions can actually affect the performance of the laser.

The Surgery
LASIK eye surgery typically takes between 20 - 30 minutes for both eyes. You will go into the surgery suite, where the operation will take place. You will be asked to lie down on a gurney or chair, and the staff will position you beneath the laser. You may be given a mild sedative, such as valium to relax you. You will be given eye drops that will numb the eye, so you won't feel anything. The area around your eyes will be thoroughly cleaned and prepped. The surgical team will assemble and go over the specifics of your case with you, confirming the treatment. Then the surgery will begin.

A lid speculum will be placed around your eyes to keep the lids open while the surgeon works. Then, a device will be placed over your eyeball that will hold it in place. You may feel some pressure because of the mild suction created. This will block your vision for a while. Then, the surgeon will use the microkeratome to create the corneal flap. The microkeratome is removed, then the suction device. You will be able to see, but since the flap has been created, your vision is likely to be blurry throughout the rest of the procedure.

The surgeon then carefully moves the flap out of the way to expose the stromal tissue beneath. Excess moisture is removed from your eye, then measurements of the thickness of the cornea will be made with a pachymeter. The laser is then positioned over your eye. You will be asked to stare directly into the light he or she will shine into your eye. That light is not the laser; it is simply a point of reference so the eye remains in position.

The laser is then activated, and the surgeon will begin the ablation (removal of tissue). Usually, this part of the procedure takes less than a minute, although it varies from patient to patient, depending on the amount of tissue removed. You may hear noises, such as clicking or ticking and smell something that some have described as like burning hair. The clicking is the sound of the laser pulsing to remove the excess tissue; the smell is from the evaporation of the fluid and tissue from the cornea during the procedure. After this is complete, the surgeon places the flap back into position. A protective shield will be placed over your eye, so you won't accidentally rub or put any pressure on it. If both eyes are to be treated, the surgeon then moves to the other eye and the procedure is repeated.

After Surgery
As soon as surgery is done, you may feel some itching, burning, irritation or feel like there is something in your eye. They will probably be watering a lot and your vision will be somewhat blurry. This is normal, and it's very important to not touch your eyes, under any circumstances. There are no stitches in this surgery, so the corneal flap can be easily moved out of position if you touch it.

LASIK Risks
Although LASIK is very popular, due to its very high success rate, the risks surrounding this surgery must be taken into account. Many of these risks can be neutralized by selecting an experienced, recommended surgeon and strictly following the surgeon's instructions before, during and after surgery. Complications following LASIK surgery are declining every year. However, even in the best of circumstances, things can go wrong. The good news here is that most complications can be corrected by another surgery. Common complications include:

• Corneal Striae
  The striae are microscopic wrinkles that may be caused by the corneal flap either being cut incorrectly, replaced incorrectly or by the patient rubbing the eye too soon after surgery. The wrinkles cause an irregular corneal surface, which will cause visual acuity to be less than expected. Flap complications like this happen in from .03% to 5.7% of all LASIK procedures, according to a 2006 issue of American Journal of Opthalmology. Inexperienced surgeons appear to be one of the main causes of this defect, so choose your surgeon with care.
• Irregular Astigmatism
  Not centering the laser properly can result in this defect, causing the stromal layer to be improperly shaped. Symptoms include ghosting or double vision. This can be corrected by additional surgery.
• Diffuse Lamellar Keratitis (DLK)
  Also called 'Sands of the Sahara', DLK is an inflammation of the eye under the corneal flap, which makes the eye feel as if it has sand in it. DLK can be caused by several factors. Some inflammation is normal, but if symptoms are not addressed, permanent damage can result. DLK usually responds well to antibiotic and steroid treatment. Sometimes the flap needs to be lifted and cleaned of any inflamed cells, then replaced. Contact your surgeon if you experience irritation beyond what you expect.
• Keratectasia or keratoconus
  This is a bulging of the eye's surface and is one of the more severe complications resulting from LASIK surgery. A corneal flap cut too deeply, the removal of too much tissue or an existing weakness in the cornea prior to the surgery, may cause this. The distortion of the vision from keratectasia is not likely to respond well to surgical repair and the patient may have to wear gas-permeable lenses or corneal implants (Intacs) to hold the shape of the cornea. Other treatments for this condition may be appropriate.
• Other complications may include over or under-correction, residual astigmatism, decentered ablation, visual haze, dry eye, ingrowth of the epithelium (the layer of cells that cover the surface of the cornea) and infection. Many of these complications can be reduced and avoided altogether if the surgeon performing the LASIK procedure is experienced and reputable. Minor complications which readily resolve themselves are subconjunctival hemorrhage, inflammation and dry eye.