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.
Contact lens quality continues to improve. Soft contacts contain from 25 percent to 79 percent water, are easy to adjust to, and are more comfortable than rigid gas permeable (RGP) lenses, thanks to their ability to conform to the eye and absorb water. Soft lenses aren't likely to pop out or capture foreign material such as dust underneath, as hard lenses are. Extra-thin soft lenses are available for very sensitive eyes.
While the ability to hold water increases oxygen permeability of soft lenses, it also makes them more fragile. And soft lenses are more likely to absorb chemicals and residues on the wearer's hands.
RGP lenses are more durable and resistant to deposit buildup, and they generally give clearer, crisper vision. They tend to be less expensive over the life of the lens, but the initial cost often is higher. RGP contacts last several years, while soft contacts, depending on the type, are meant to be replaced after periods ranging from a day to about a year. In addition, RGP lenses can be marked to show which lens is for which eye, and they're less likely to tear or rip, making them easier to handle. However, it often takes several weeks to get used to wearing rigid lenses, compared with several days for soft.
Many changes are occurring in the world of disposable (defined by the FDA as used once and discarded) and frequent- or planned-replacement contacts. The latest innovations include daily disposables, bifocals and toric contacts for astigmatism.
"It's healthier to replace lenses more often," says James Saviola, O.D., chief of the vitreoretinal and extraocular devices branch in the FDA. "And if you reuse your lenses, you need to do something more than store them in saline solution." The FDA approved in 2000 the first "no-rub" cleaning solution for contact lenses. The solution adds a safeguard for people who do not rub their lenses--but should--when cleaning. The no-rub directions for this first solution initially applied to lenses replaced within a month or less. Now, it has been expanded to include lenses that are replaced after a month or more. Other products also are available that have no-rub directions for lenses replaced within a month. But Saviola reminds people that in some cases, rubbing is still necessary to keep their lenses clean.
A new generation of lens materials is being studied. Lenses made of these materials provide a greater amount of oxygen permeability, says Saviola. Two types have received FDA approval, one for seven days of continuous wear, the other for 30 days. Others, such as the 30-day continuous wear contact, now are being considered.
The most serious safety concerns with any contact lens deal with overnight use, or extended-wear. Rigid or soft, wearing these types of contacts overnight increases the risk of corneal ulcers--infection-caused eruptions on the cornea that can lead to blindness. Symptoms include vision changes, eye redness, eye discomfort, and excessive tearing. Extended-wear rigid lenses also can cause unexpected, sometimes undesirable reshaping of the cornea. Saviola advises that keeping lenses clean, replacing them often, and wearing them as prescribed by your eye-care specialist increases the safety of wearing contacts.
People should not wear contact lenses longer than the time prescribed by their eye-care practitioner. But whatever he or she prescribes, be sure to ask for written instructions and follow them carefully. Patient package inserts usually accompany contact lenses, and Saviola emphasizes that people who are not offered this information by their doctors should ask for it.
For those who haven't been able to wear contacts, implantable lenses may be an option in the future.
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