Vision Correction: Part 2

by Food and Drug Administration (FDA)

(Page 2 of 4)

While most people are pleased with the results of their surgery, O'Brien says that, as with any medical procedure, there are risks involved. Some include: over- or under-treatment; the inability to wear contact lenses; permanent loss of vision; reduction in the quality of vision including the development of glare, halos, and starbursts; difficulty with night-driving; and reduced vision in dim lighting conditions. The risks are doubled when both eyes are treated at the same time.

Also, LASIK is not reversible. That's why in Polazzo's case, O'Brien intentionally undercorrected her distance eye. "We were aiming for modified monovision," he explains, which means that one eye would see close up while the other would be corrected to see distances. But Polazzo experienced some regression in her distance eye — that is, her distance vision began to worsen as she returned to nearsightedness — some weeks following surgery. However, because of the initial undercorrection, O'Brien was able to fix the problem.

A. Ralph Rosenthal, M.D., director of the Food and Drug Administration's division of ophthalmic and ear, nose and throat devices in the Center for Devices and Radiological Health, says that no one knows the long-term effects of laser eye surgery. "We just can't know that yet," he says, so when people call looking for a guarantee in years for the success of the procedure, "I can't give them one."

Before undergoing LASIK, Rosenthal says people should carefully weigh the risks and benefits based on what's important to them, and potential side effects, including the pros and cons of having one or both eyes done on the same day. It's also important to avoid being influenced by friends who have had LASIK surgery or doctors who encourage patients to do so.

A second laser procedure used today as an alternative to LASIK is photorefractive keratectomy, or PRK. Although O'Brien says that less than 5 percent of people undergo PRK, it is still the procedure of choice for certain eye conditions. This type of refractive surgery gently reshapes the cornea by removing microscopic amounts of tissue from the outer surface with a cool, computer-controlled ultraviolet beam of light. It does not, however, involve cutting. The procedure takes only a few minutes, and patients are typically back to daily routines in five to seven days.

Clinical studies indicate that about 5 percent of PRK recipients continued to need glasses for distance vision following the surgery, and up to 15 percent need glasses occasionally, such as when driving. In addition, many people experienced mild corneal haze following surgery, which is part of the normal healing process. The haze appeared to have little or no effect on final vision, and could only be seen by a doctor under a microscope. For about 5 percent of PRK patients, best-corrected vision without corrective lenses was slightly worse after surgery than before. These conditions, however, improved or disappeared in most people in six months.

Another new, less-invasive laser procedure — indicated for temporarily reducing hyperopia — is being aimed exclusively at people over 40. Laser thermal keratoplasty, or LTK, involves zapping 16 spots on the outer part of the cornea to shrink the tissue. People usually can leave 30 minutes after the procedure and resume normal activities the following day. The advantage of LTK is that it's a "no touch" procedure, meaning there's little chance of infection or loss of vision. The disadvantage is that the procedure is considered temporary since the treatment effect regresses — for many people, about half of the correction is gone within two years. Another drawback is that people may become nearsighted in the first six weeks, enough to require glasses for driving, and their vision can fluctuate for weeks after surgery.

Rosenthal wants people considering laser surgery to know and carefully weigh the pros and cons. "FDA mandated that manufacturers of all excimer lasers make available to people a patient information booklet," he says, that spells out this information. If the doctor fails to offer one, Rosenthal says that you should ask for it.

Experts say that the reliability of laser vision correction is quite good in mild to moderate levels of refractive errors. But people desperate for clear vision need to understand the dangers. The most satisfied laser surgery patient is one who has realistic expectations and a thorough understanding of the risks and possible complications of refractive surgery.

Contact Lenses — More Choices

Whether you're interested in wearing contact lenses for the first time, or are considering an upgrade for comfort and convenience, discussing the latest innovations with your eye-care practitioner will help make your choices easier and minimize the risks. Advances in materials for precision lenses have made soft and rigid gas permeable contacts — the two main contact lens groups — an option for more people. These medical devices are made of many different types of plastic, and offer numerous options. With daily wear or extended wear (overnight) lenses, the options include frequent- or planned-replacements, disposables, bifocals, UV-blocking contacts, and more. There are clear, tinted, opaque, spherical and rounded lenses. So where does someone start when deciding if contact lenses are the right choice for vision correction, and what to choose?

Hal Balyeat, M.D., professor of ophthalmology at the University of Oklahoma's Dean A. McGee Eye Institute, says people satisfied with their vision correction may not need to look very far. "If you are already a satisfied contact wearer," he says, "you may not consider other options worthwhile when you're wearing your contacts as well as you are." Satisfied wearers typically have no allergies and have not developed an intolerance to contact lenses. The bottom line: If contact lenses are working for you, Balyeat says, it's hard to justify other options, such as permanent laser alteration of otherwise healthy eyes.

Balyeat cites his wife, Marilyn, as an example. Although she was a good candidate for the LASIK surgery, she opted for monovision contacts — one lens focuses close up while the other lens corrects for distance vision. "At 60," she says, "I can still read without glasses." And that, says her husband, is the single most important factor: "If you like being able to take out your contacts and still see up close, surgery is not a worthwhile trade-off." Balyeat adds that many people don't realize that laser surgery, performed on people over 40, won't let you see up close without glasses or contacts unless you opt for monovision LASIK.

About the Author

www.fda.gov
FDA is A United States government body that oversees medical devices, including contact lenses, intraocular lenses, excimer lasers and eyedrops. In the US, these products must be approved by the FDA before they can be marketed.