A new generation of recently approved contact lenses offers such a dramatic improvement in comfort, convenience and safety that some people are forgoing the popular laser eye surgery to correct their vision.
Thanks to new lens materials, consumers can now safely wear contacts around-the-clock for up to 30 days, without the hassle of taking the lenses out at night, cleaning them and re-inserting them in the morning. And the new lenses have been shown to be safer to wear for extended periods than competing types of lenses worn for less time, according to several eye doctors who have tested them in clinical trials.
"It's like the difference between DVDs and videos," said Dr. Dwight Cavanagh, vice chairman of ophthalmology at the University of Texas Southwestern Medical Center in Dallas. "Once you've seen a DVD, you don't buy any more videos."
The new products are CIBA Vision's Focus Night & Day soft lenses and Menicon Co.'s Menicon Z rigid gas permeable lenses. The Food and Drug Administration approved the products for 30-day wear in the United States during the past year, but the new lenses have been slow to catch on with consumers and doctors.
"These are exciting lenses," said Dr. Gary Foulks, professor of ophthalmology and director of clinical research at UPMC Eye & Ear Institute.
Like other eye doctors, he called them an "excellent alternative" for consumers who are considering Lasik surgery, a popular technique used to correct nearsightedness. Some patients have been reluctant to undergo the costly procedure because of concern about possible complications, such as dry eyes or problems with glare.
The new lenses allow at least double -- and in many cases, six to eight times -- as much oxygen to nourish the cornea as brands now on the market. Inadequate oxygen to the eyes is believed to have been a chief cause of earlier problems with continuous-wear lenses that led to sight-threatening infections and corneal ulcerations.
After approving some contacts for 30-day "continuous wear" in the 1970s, the FDA in 1989 set tighter restrictions on the lenses, allowing a maximum "extended wear" time of just seven days.
Foulks, past president of the Contact Lens Association of Ophthalmologists, said studies on the new lenses conducted in countries that have had these available longer show a very slight risk. In a large study in Sweden, there were no incidences of infection, he said. There were four cases of infection reported in a recent study in Australia, a very small number comparatively, and none resulted in severe eye damage.
"In controlled studies they have performed extremely well, from what we know about how they affect the cornea and adherence of bacteria ... they performed better than other lenses," he said.
Eye doctors are aware of the new lenses, but are suspicious of continuous-wear lenses because of the bad publicity that the first generation of these products received in the 1980s, when some patients suffered severe corneal infections.
"It's a once burned, twice shy situation for optometrists and ophthalmologists," Foulks said.
The new lenses, which sell for between $200 and $500, including fittings, are made of plastics that allow the eyes to breathe "just like lungs do," says Mary Jo Stiegemeier, a Beachwood, Ohio, optometrist who participated in the FDA trials of Menicon Z lenses. She was initially apprehensive about allowing her patients to sleep with their lenses on for weeks on end.
After a month of continuous wear, however, their corneas looked "like they'd never worn a contact lens" -- a significant improvement from the aftermath of wearing other kinds of lenses for less time, she said.
The new lenses also significantly minimize the adherence of bacteria. The lens surface is more natural and "bio harmonious with the molecules of the body, which is extremely important, said Joseph Barr, a professor of optometry at Ohio State University and editor of Contact Lens Spectrum, a medical journal.
The two lenses are made from different materials and function differently. Menicon's lens, which is thin and bendable but still considered "rigid," is a copolymer of the materials siloxanylstyrene and fluoro-methacrylate, touted as strong yet porous.
CIBA Vision's soft, rubbery Focus Night & Day lens are made of silicone hydrogel.
Consumers generally aren't aware of how much difference there is between brands of lenses -- even those in the same general category such as soft or rigid gas permeable lenses.
Post-Gazette Health Editor Virginia Linn contributed to this report.
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