The Basics of LASIK Eye Surgery

LASIK Basics

If you wear glasses or contact lenses, you might think about surgery to correct your vision. In a LASIK procedure, a laser is used to reshape your cornea — the clear, round dome at the front of your eye — to improve the way your eye focuses light rays onto your retina. LASIK is shorthand for laser-assisted in situ keratomileusis.

Before you sign up for this surgery, here are a few things to think about:

• LASIK is surgery to a very delicate part of your eye, and cannot be reversed.
• As with any surgery, there are risks and possible complications.
• Millions of people have had LASIK, many very successfully, but it’s not for everyone.
• LASIK may not give you perfect vision. The American Academy of Ophthalmology (AAO) reports that nine out of 10 patients achieve somewhere between 20/20 and 20/40 vision, but 20/40 vision may not be sharp enough for certain work or leisure activities. Even 20/20 does not always mean perfect vision. Detailed, precise vision may be slightly diminished.
• Even with LASIK to correct your distance vision, you are likely to need reading glasses in your mid-40s. LASIK surgery cannot correct or prevent presbyopia, the age-related loss of focusing power for seeing near objects.
• If you are nearsighted and don't yet need reading glasses, having LASIK may mean you will need reading glasses earlier than if you had not had the surgery.
• The benefits of the LASIK procedure may diminish over time. More than 10 percent of LASIK patients in the U.S. require a second surgery, called “retreatment,” to restore the desired vision correction. This is more likely for people who were more nearsighted or farsighted, or had higher astigmatism before LASIK.
• Most insurance plans don’t cover the surgery.

Understanding Your Eyes

To see clearly, the cornea and the lens must bend, or refract, light rays so they focus on the retina — a layer of light-sensing cells that line the back of the eye. The retina converts the light rays into impulses that are sent to the brain, where they are recognized as images. If the light rays don’t focus on the retina, the image you see is blurry. This is called a refractive error. Glasses, contact lenses, and refractive surgery try to reduce these errors by making light rays focus on the retina.

Refractive errors are caused by an imperfectly shaped eyeball, cornea, or lens — or in the case of presbyopia, a lens that can't change shape enough to focus on close objects — and are of these basic types:

• myopia is another word for nearsightedness, where only nearby objects are clear or distinct
• hyperopia is another word for farsightedness, where only objects far away are clear or distinct
• astigmatism is when images are blurred, regardless of whether they are near or far
• presbyopia, or "aging eye," is a condition that typically develops between ages 40 and 50 and makes it more difficult to see very close. It can be corrected with bifocals or reading glasses, but usually can't be corrected by LASIK or some other refractive surgery.

Are You a Good Candidate for LASIK?

LASIK isn’t for everyone

• You should be at least 18 years old (21 for some lasers). The vision of people younger than 18 still is changing.
• You shouldn’t be pregnant or nursing. It might change the measured refraction of the eye.
• You shouldn’t be taking certain prescription drugs, like Accutane or oral prednisone.
• Your eyes must be healthy and your prescription stable. If you’re myopic, you should postpone LASIK until your refraction has stabilized. Myopia may continue to increase in some patients until their mid- to late 20s.
• Your general health should be good. LASIK may not be recommended for patients with diabetes, rheumatoid arthritis, lupus, glaucoma, herpes infections of the eye, cataracts, disorders of the cornea, and retinal disease. Discuss your general health status with your surgeon.
• A history of “dry eye” could matter. If you’ve had problems with dry eye, from wearing contact lenses, taking certain medications, or some other reason, talk to your eye doctor about how it could impact LASIK. You should be screened for dry eye before you have LASIK or other refractive surgery.

Other considerations

• The risks and rewards. If you’re happy wearing contacts or glasses, you may want to forgo the surgery.
• Your expectations from the surgery. Are they realistic? In general, having very poor eyesight reduces the chance of LASIK success and increases the chance of retreatment.
• Workplace requirements and lifestyle activities. Discuss work, sports, and recreation with your doctor to make sure LASIK is appropriate for you.
• If you're a candidate for monovision, which corrects one eye for distance vision and the other eye for near vision. LASIK cannot correct presbyopia so that one eye can see both near and far. However, it can be used to correct one eye for distance and the other for near vision. If you can adjust to this correction, it may eliminate or reduce your need for reading glasses. Yet monovision has its own risks:
  • After monovision, the two eyes no longer work together. This causes poorer quality vision and a decrease in depth perception. These effects are most noticeable in low lighting conditions and when performing tasks requiring very sharp vision.
  • As a result, you may need to wear glasses or contact lenses for distance or near vision when performing visually demanding tasks, such as driving at night, operating dangerous equipment, or performing occupational tasks requiring very sharp, close vision.   

Finding a Surgeon

Only ophthalmologists are permitted to perform LASIK. Ask your ophthalmologist or optometrist for a referral to a medical doctor who performs LASIK. The American Academy of Ophthalmology (AAO) can provide you with a list of its members who perform LASIK. About 95 percent of all ophthalmologists are AAO members.

Questions to ask your surgeon

• How long have you been doing LASIK surgery?
• How much experience do you have with the LASIK procedure?
• How do you define success? What’s your success rate? What is the chance for me (with my correction) to achieve 20/20? How many of your patients have achieved 20/20 or 20/40 vision? How many patients return for retreatments? (A five to 15 percent return is not unusual.)
• What laser will you be using for my surgery? Make sure the surgeon is using a laser approved by the U.S. Food and Drug Administration (FDA). Visit www.fda.gov/lasik for more information.  
• What’s involved in after-surgery care?
• Who will handle my after-surgery care? Who will be responsible?
• What are the risks and possible complications?

Risks and Complications

Before the surgery, your surgeon should explain the risks and possible complications, including the pros and cons of having one or both eyes done on the same day. This is the “informed consent” process.

Risks

• Blindness and irreversible eye damage. In rare cases, errors during surgery (like the malfunctioning of the laser device) or complications after surgery (for example, inflammation) may cause irreversible damage to the eye, including permanent blindness. In other cases, the problems can be corrected with additional surgeries or other treatments.
• Vision loss. You may not see as well after the surgery — even with glasses or contacts — as you did with glasses or contacts before the surgery. Or, you may need glasses or contacts to see as well as you did before surgery.
• Severe night vision problems. You may develop debilitating visual symptoms, particularly glare, halos, and/or double vision that can seriously affect nighttime vision.
• Decrease in contrast sensitivity, “crispness,” or sharpness. Objects may appear fuzzy or grayish. Even with good vision on the vision chart, you may not see as well in situations of low contrast — like at night or in fog — after treatment compared to before.
• Severe dry eye syndrome. As a result of surgery, your eye may not be able to produce enough tears to keep it moist and comfortable. Dry eye not only causes discomfort, but can reduce visual quality due to intermittent blurring and other visual symptoms. This condition may be permanent. Intensive drop therapy and use of plugs or other procedures may be required.

Complications

• Corneal infection or inflammation. These problems may require additional surgery or other treatments.
• Problems with the corneal flap after surgery. These include irregular or incomplete flaps, ingrowth of cells under the flap that may need to be surgically removed, and irregular healing that results in a distorted cornea, which can only be corrected with a corneal transplant.

What to Expect Before, During, and After Surgery

Before

You’ll need a complete eye examination by your refractive surgeon. Your referring eye care professional may perform a preliminary eye exam. Take your eye prescription records with you to the exams. If you wear contact lenses, stop wearing them before your baseline evaluation (soft contact lenses — two weeks; toric soft lenses or rigid gas permeable lenses — three weeks; hard lenses — four weeks). Contacts can temporarily change the shape of the cornea and compromise precise measurements in the pre-op exam.

Your doctor should:

• dilate your pupils to fine-tune your prescription
• examine your eyes to make sure they’re healthy, including testing for glaucoma, performing a retinal exam, and assessing for dry eye
• take the following measurements:
  • the curvature of your cornea and your pupils
  • the topography of your eyes, to make sure you don’t have an irregular astigmatism or a cone-shaped cornea — a condition called keratoconus
  • the thickness of your cornea. You need to have enough tissue left after your corneas have been cut and reshaped.
• ask you to sign an informed consent form after a thorough discussion of the risks, benefits, options, and possible complications of LASIK surgery. Review the form carefully, and don’t sign until you understand everything in the form.

If your doctor doesn’t think LASIK is right for you, you might consider getting a second opinion; however, if the opinion is the same, believe it.

If you qualify for surgery, your doctor may tell you to stop wearing your contact lenses for a while before the surgery for the same reason that you stopped wearing them before your baseline exam: contacts can temporarily change the shape of the cornea. Your cornea should be in its natural shape the day of surgery. Your doctor also may tell you to stop wearing makeup, lotions, or perfume for a few days before surgery. These products can interfere with the laser treatment or increase the risk of infection after surgery.

During

LASIK is an outpatient surgical procedure. The only anesthetic is an eye drop that numbs the surface of the eye. The surgery takes 10 to 15 minutes for each eye. Sometimes, both eyes are done during the same procedure; but sometimes, surgeons wait (sometimes days or weeks) to see the result on one eye before doing surgery on the other.

The Surgical Procedure: The eye is moistened. A suction ring is positioned to keep the eye from moving and the cornea in the correct position. A special device cuts a hinged flap of thin corneal tissue off the outer layer of the eyeball (cornea) and the flap is lifted out of the way. The laser reshapes the underlying corneal tissue, and the surgeon replaces the flap, which quickly adheres to the eyeball. There are no stitches. A shield — either clear plastic or perforated metal — is placed over the eye to protect the flap.

After

Healing is relatively fast, but you may want to take a few days off from work after the surgery. Avoid sports for three days after surgery; impact sports or similar activities for four weeks. Be aware that:

• you may experience a mild burning or sensation for a few hours after surgery. Don’t rub your eye. Your doctor can prescribe a painkiller, if you need one, to ease any discomfort.
• your vision probably will be blurry the day of surgery, but it should improve considerably by the next day when you return for a follow-up exam
• you should report aggravating or unusual side effects to your doctor immediately
• you shouldn’t drive until your vision has improved enough to do so safely
• you should avoid swimming, hot tubs, and whirlpools for two weeks after surgery

Surgical Alternatives to LASIK

You may want to discuss some surgical alternatives to LASIK with your eye doctor. In general, these procedures are relatively new and are performed less often than traditional LASIK surgery.

Photorefractive Keratectomy (PRK)

In surgery using PRK, including Epi-LASIK and LASEK, surgeons use lasers to create “surface ablations” on the cornea without creating a corneal flap. Because these procedures cut only the very top (epithelial) layer of the cornea, the risk of certain complications associated with LASIK surgery may be reduced.

Conductive Keratoplasty (CK)

This is a thermal refractive surgery procedure used to correct mild to moderate farsightedness (hyperopia) in people over age 40 by use of a tiny probe that releases controlled amounts of radio frequency (RF) energy, instead of a laser, to apply heat to the peripheral portion of the cornea. Farsightedness may return over time.

Phakic Intraocular Lens (IOL)

An IOL is a form of contact lens that is surgically implanted inside the eye in front of the lens. These implants are used to correct vision problems caused by cataracts and other refractory problems that are too severe to be corrected with corneal-based refractive surgery. Certain types of IOLs, such as Multifocal or accommodative lenses, may not only improve distance vision but also eliminate the need for reading glasses.

For More Information

For more information about vision correction procedures, contact:

American Academy of Ophthalmology (AAO)
The AAO works to advance the lifelong learning and professional interests of ophthalmologists to ensure that the public can obtain the best possible eye care.

American Society of Cataract and Refractive Surgery (ASCRS)
The ASCRS works to raise the standards and skills of anterior segment surgeons through clinical and practice management education. The Society also works with patients, government, and the medical community to promote delivery of quality eye care.

International Society of Refractive Surgery (ISRS)
The ISRS provides scientific research, knowledge, and information to all individuals who are interested in refractive surgery.

National Eye Institute (NEI)
The NEI conducts and supports research on eye diseases and vision disorders, and offers free publications for the general public and patients.

Food and Drug Administration (FDA)
FDA oversees the safety of food, cosmetics, medicines, medical devices, and radiation- emitting products and provides information on contact lenses, intraocular lenses, refractive surgery, and corneal implants for myopia.