Lasik Eye Surgery

The LASIK Procedure
LASIK stands for Laser-Assisted In Situ Keratomileusis and is a surgical vision correction procedure that reduces a person's dependency on glasses or contact lenses.  The LASIK procedure has never before been as safe as it is today.

The LASIK procedure permanently changes the shape of the cornea, the clear covering of the front of the eye, using an excimer laser. In some surgeries, a knife, called a microkeratome, is used to cut a flap in the cornea. In other surgeries, a laser makes this cut. A hinge is left at one end of this flap. The flap is folded back revealing the stroma, the middlesection of the cornea. Pulses from a computer-controlled laser vaporize a portion of the stroma and the flap is replaced.

The Anatomy of LASIK Surgery
The cornea is a part of the eye that helps focus light to create an image on the retina. It works in much the same way that the lens of a camera focuses light to create an image on film. The bending and focusing of light is also known as refraction. Usually the shape of the cornea and the eye are not perfect and the image on the retina is out-of-focus (blurred) or distorted. These imperfections in the focusing power of the eye are called refractive errors. There are three primary types of refractive errors: myopia, hyperopia and astigmatism. Persons with myopia, or nearsightedness, have more difficulty seeing distant objects as clearly as near objects. Persons with hyperopia, or farsightedness, have more difficulty seeing near objects as clearly as distant objects. Astigmatism is a distortion of the image on the retina caused by irregularities in the cornea or lens of the eye. Combinations of myopia and astigmatism or hyperopia and astigmatism are common. Glasses or contact lenses are designed to compensate for the eye's imperfections. Refractive surgical procedures such as LASIK are aimed at improving the focusing power of the eye. In LASIK surgery, precise and controlled removal of corneal tissue by a special laser reshapes the cornea changing its focusing power and bringing to the individual unaided clearer vision.

Other Types of Refractive Surgery
Radial Keratotomy or RK and Photorefractive Keratectomy or PRK are other refractive surgeries used to reshape the cornea. In RK, a very sharp knife is used to cut slits in the cornea changing its shape. PRK was the first surgical procedure developed to reshape the cornea, by sculpting, using a laser. Later, LASIK was developed. The same type of laser is used for LASIK and PRK. Often the exact same laser is used for the two types of surgery. The major difference between the two surgeries is the way that the stroma, the middle layer of the cornea, is exposed before it is vaporized with the laser. In PRK, the top layer of the cornea, called the epithelium, is scraped away to expose the stromal layer underneath. In LASIK, a flap is cut in the stromal layer and the flap is folded back.

Another type of refractive surgery is thermokeratoplasty in which heat is used to reshape the cornea. The source of the heat can be a laser, but it is a different kind of laser than is used for LASIK and PRK. Other refractive devices include corneal ring segments that are inserted into the stroma and special contact lenses that temporarily reshape the cornea (orthokeratology).

The goal of this Web site is to provide objective information to the public about LASIK surgery and other refractive vision correction procedures. See other sections of this site to learn about what you should know before surgery, what will happen during the surgery, and what you should expect after surgery.

What You Should Know Before The Surgery
What to expect before surgery will vary from doctor to doctor and patient to patient. This section is a compilation of patient information developed by manufacturers and healthcare professionals, but cannot replace the dialogue you should have with your doctor. Read this information carefully and with the checklist, discuss your expectations with your doctor

If you decide to go ahead with LASIK surgery, you will need an initial or baseline evaluation by your eye doctor to determine if you are a good candidate. This is what you need to know to prepare for the exam and what you should expect:

If you wear contact lenses, it is a good idea to stop wearing them before your baseline evaluation and switch to wearing your glasses full-time. Contact lenses change the shape of your cornea for up to several weeks after you have stopped using them depending on the type of contact lenses you wear. Not leaving your contact lenses out long enough for your cornea to assume its natural shape before surgery can have negative consequences. These consequences include inaccurate measurements and a poor surgical plan, resulting in poor vision after surgery. These measurements, which determine how much corneal tissue to remove, may need to be repeated at least a week after your initial evaluation and before surgery to make sure they have not changed, especially if you wear RGP or hard lenses.

If you wear:

• soft contact lenses, you should stop wearing them for 2 weeks before your initial evaluation.
• toric soft lenses or rigid gas permeable (RGP) lenses, you should stop wearing them for at least 3 weeks before your initial evaluation.
• hard lenses, you should stop wearing them for at least 4 weeks before your initial evaluation.

You should tell your doctor:

• about your past and present medical and eye conditions
• about all the medications you are taking, including over-the-counter medications and any medications you may be allergic to

Your doctor should perform a thorough eye exam and discuss:

• whether you are a good candidate
• what the risks, benefits, and alternatives of the surgery are
• what you should expect before, during, and after surgery
• what your responsibilities will be before, during, and after surgery

You should have the opportunity to ask your doctor questions during this discussion. Give yourself plenty of time to think about the risk/benefit discussion, to review any informational literature provided by your doctor, and to have any additional questions answered by your doctor before deciding to go through with surgery and before signing the informed consent form.

You should not feel pressured by your doctor, family, friends, or anyone else to make a decision about having surgery. Carefully consider the pros and cons.

The day before surgery, you should stop using:

• creams
• lotions
• makeup
• perfumes

These products as well as debris along the eyelashes may increase the risk of infection during and after surgery. Your doctor may ask you to scrub your eyelashes for a period of time before surgery to get rid of residues and debris along the lashes.

Also before surgery, arrange for transportation to and from your surgery and your first follow-up visit. On the day of surgery, your doctor may give you some medicine to make you relax. Because this medicine impairs your ability to drive and because your vision may be blurry, even if you don't drive make sure someone can bring you home after surgery.
What You Should Do During The Surgery
What to expect during surgery will vary from doctor to doctor and patient to patient. This section is a compilation of patient information developed by manufacturers and healthcare professionals, but cannot replace the dialogue you should have with your doctor. Read this information carefully and with the checklist, discuss your expectations with your doctor.
The surgery should take less than 30 minutes. You will lie on your back in a reclining chair in an exam room containing the laser system. The laser system includes a large machine with a microscope attached to it and a computer screen.
A numbing drop will be placed in your eye, the area around your eye will be cleaned, and an instrument called a lid speculum will be used to hold your eyelids open. A ring will be placed on your eye and very high pressures will be applied to create suction to the cornea. Your vision will dim while the suction ring is on and you may feel the pressure and experience some discomfort during this part of the procedure. The microkeratome, a cutting instrument, is attached to the suction ring. Your doctor will use the blade of the microkeratome to cut a flap in your cornea.

The microkeratome and the suction ring are then removed. You will be able to see, but you will experience fluctuating degrees of blurred vision during the rest of the procedure. The doctor will then lift the flap and fold it back on its hinge, and dry the exposed tissue.

The laser will be positioned over your eye and you will be asked to stare at a light. This is not the laser used to remove tissue from the cornea. This light is to help you keep your eye fixed on one spot once the laser comes on. NOTE: If you cannot stare at a fixed object for at least 60 seconds, you may not be a good candidate for this surgery.

When your eye is in the correct position, your doctor will start the laser. At this point in the surgery, you may become aware of new sounds and smells. The pulse of the laser makes a ticking sound. As the laser removes corneal tissue, some people have reported a smell similar to burning hair. A computer controls the amount of laser delivered to your eye. Before the start of surgery, your doctor will have programmed the computer to vaporize a particular amount of tissue based on the measurements taken at your initial evaluation. After the pulses of laser energy vaporize the corneal tissue, the flap is put back into position.

A shield should be placed over your eye at the end of the procedure as protection, since no stitches are used to hold the flap in place. It is important for you to wear this shield to prevent you from rubbing your eye and putting pressure on your eye while you sleep, and to protect your eye from accidentally being hit or poked until the flap has healed.
What You Should Do After The Surgery
What to expect after surgery will vary from doctor to doctor and patient to patient. This section is a compilation of patient information developed by manufacturers and healthcare professionals, but cannot replace the dialogue you should have with your doctor. Read this information carefully and with the checklist, discuss your expectations with your doctor.
Immediately after the procedure, your eye may burn, itch, or feel like there is something in it. You may experience some discomfort, or in some cases, mild pain and your doctor may suggest you take a mild pain reliever. Both your eyes may tear or water. Your vision will probably be hazy or blurry. You will instinctively want to rub your eye, but don't! Rubbing your eye could dislodge the flap, requiring further treatment. In addition, you may experience sensitivity to light, glare, starbursts or haloes around lights, or the whites of your eye may look red or bloodshot. These symptoms should improve considerably within the first few days after surgery. You should plan on taking a few days off from work until these symptoms subside. You should contact your doctor immediately and not wait for your scheduled visit, if you experience severe pain, or if your vision or other symptoms get worse instead of better.

You should see your doctor within the first 24 to 48 hours after surgery and at regular intervals after that for at least the first six months. At the first postoperative visit, your doctor will remove the eye shield (if applicable), test your vision, and examine your eyes. Your doctor may give you one or more types of eye drops to take at home to help prevent infection and/or inflammation. You may also be advised to use artificial tears to help lubricate the eye. Do not resume wearing a contact lens in the operated eye, even if your vision is blurry.
You should wait one to three days following surgery before beginning any non-contact sports, depending on the amount of activity required, how you feel, and your doctor's instructions.

To help prevent infection, you may need to wait for up to two weeks after surgery or until your doctor advises you otherwise before using lotions, creams, or make-up around the eye. Your doctor may advise you to continue scrubbing your eyelashes for a period of time after surgery. You should also avoid swimming and using hot tubs or whirlpools for 1-2 months.

Strenuous contact sports such as boxing, football, karate, etc. should not be attempted for at least four weeks after surgery. It is important to protect your eyes from anything that might get in them and from being hit or bumped.

During the first few months after surgery, your vision may fluctuate.

• It may take up to three to six months for your vision to stabilize after surgery.
• Glare, haloes, difficulty driving at night, and other visual symptoms may also persist during this stabilization period. If further correction or enhancement is necessary, you should wait until your eye measurements are consistent for two consecutive visits at least 3 months apart before re-operation.
• It is important to realize that although distance vision may improve after re-operation, it is unlikely that other visual symptoms such as glare or haloes will improve.
• It is also important to note that no laser company has presented enough evidence for the FDA to make conclusions about the safety or effectiveness of enhancement surgery.

Contact your eye doctor immediately, if you develop any new, unusual or worsening symptoms at any point after surgery. Such symptoms could signal a problem that, if not treated early enough, may lead to a loss of vision.

Source: U.S. Food and Drug Administration, Center for Devices and Radiological Health
Are You a Candidate for LASIK?
Who is Right for Laser Eye Surgery? While many individuals are considered good candidates for LASIK, there are some who do not meet the generally accepted medical criteria to ensure a successful laser vision procedure. Individuals that are not deemed good candidates given today’s technology may be able to have the surgery in the future, as technology advances and new techniques are refined. Anyone considering laser eye surgery must have a thorough examination by an ophthalmologist that will help determine, in consultation with the patient, whether or not the LASIK procedure is right for them. Based on various conditions and circumstances, all LASIK candidates will fall into one of the following three broad categories:

The Ideal LASIK Candidate
The ideal candidate includes those who:
• Are over 18 years of age and have had a stable glasses or contact lens prescription for at least two years.
• Have sufficient corneal thickness (the cornea is the trans-parent front part of the eye). A LASIK patient should have a cornea that is thick enough to allow the surgeon to safely create a clean corneal flap of appropriate depth.
• Are affected by one of the common types of vision problems or refractive error – myopia (nearsightedness), astigmatism (blurred vision caused by an irregular shaped cornea), hyperopia (farsightedness), or a combination thereof (e.g., myopia with astigmatism). Several lasers are now approved by the U.S. Food and Drug Administration (FDA) as safe and effective for use in LASIK, but the scope of each laser’s approved indication and treatment range is limited to specified degrees of refractive error.
• Do not suffer from any disease, vision-related or otherwise, that may reduce the effectiveness of the surgery or the patient’s ability to heal properly and quickly. • Are adequately informed about the benefits and risks of the procedure. Candidates should thoroughly discuss the procedure with their physicians and understand that for most people, the goal of refractive surgery should be the reduction of dependency on glasses and contact lens-es, not their complete elimination.

The ‘Less Than Ideal’ Candidate
LASIK Candidate Sometimes, factors exist that preclude a candidate from being ideal for LASIK surgery. In many cases, a surgeon may still be able to perform the procedure safely, given that the candidate and physician have adequately discussed the benefits and risks, and set realistic expectations for the results. Candidates in this category include those who:
• Have a history of dry eyes, as they may find that the condition worsens following surgery.
• Are being treated with medications such as steroids or immunosuppressants, which can prevent healing, or are suffering from diseases that slow healing, such as autoimmune disorders.

• Have scarring of the cornea.
             More often, factors exist that may keep an individual from being a candidate immediately, but do not preclude the individual from being a candidate entirely. Candidates in this category include those who:

• Are under age 18
• Have unstable vision, which usually occurs in young people. Doctors recommend that, prior to undergoing LASIK, candidates’ vision has stabilized with a consistent glasses or contact lens prescription for at least two years.

• Are pregnant or nursing.

• Have a history of ocular herpes within one year prior to having the surgery. Once a year has passed from initial diagnosis of the disease, surgery can be considered.

• Have refractive errors too severe for treatment with current technology. Although FDA-approved lasers are available to treat each of the three major types of refractive error – myopia, hyperopia and astigmatism – cur-rent FDA-approved indications define appropriate candidates as those with myopia up to -12 D, astigmatism up to 6 D and hyperopia up to +6 D. However, laser eye surgery technology is evolving rapidly, and doctors may be able to treat more severe errors in the future.
The Non-LASIK Candidate
Certain conditions and circumstances completely preclude individuals from being candidates for LASIK surgery. Non-candidates include individuals who:
• Have diseases such as cataracts, advanced glaucoma, corneal diseases, corneal thinning disorders (keratoconus or pellucid marginal degeneration), or certain other pre-existing eye diseases that affect or threaten vision.

• Do not give informed consent. It is absolutely necessary that candidates adequately discuss the procedure and its benefits and risks with their surgeon, and provide the appropriate consent prior to undergoing the surgery.

• Have unrealistic expectations. It is critical for candidates to understand that laser eye surgery, as all surgical procedures, involves some risk. In addition, both the final outcome of surgery and the rate of healing vary from person to person and even from eye to eye in each individual.