The idea of contact lenses goes back to Leonardo da Vinci, who sketched and described them back in 1508, but it was only during the 1980s that they really took off, thanks to the soft contact. Suddenly, lenses were comfortable, and so malleable they could be folded in half like a taco without breaking, unlike the stiff old-fashioned hard lenses. People could now go running and play sports without having to worry about their lenses falling out and being lost forever.
But with added convenience came an important -- and much overlooked -- drawback: Soft lenses may not be as safe as the rigid, gas-permeable type. And yet, most people -- about 85 percent of the 31 million contact lens wearers in the United States -- choose soft, according to the American Academy of Ophthalmology. (Fewer than 1 percent still wear the original old type of hard lens, and as one doctor says, they're all dying off.) An article in last week's Lancet confirms what many optometrists and ophthalmologists already know, and users do not: Soft-contact lens wearers are at higher risk for one of the worst eye infections -- microbial keratitis, a condition that although rare, can lead to blindness, or the loss of the eye completely. "I would like to
suggest that each package of soft lenses should contain a warning
on it saying 'Wearing these lenses may threaten your vision,'" says Aize Kijlstra, Ph.D., a coauthor of the study and professor of experimental ophthalmology at the University of Amsterdam. But there are no such warnings on soft lenses and many patients go through the entire procedure of getting contact lenses without ever knowing about this risk.
"Do [doctors] tell them about this? Absolutely no," says Dr. Dwight Cavanagh, the vice-chairman of ophthalmology at the University of Texas Southwestern Medical Center in Dallas, who has done many studies on the safety of contact lenses. "But even if people knew, they would still wear soft ... Consumers are perverse, they prefer the easy route -- convenience and comfort -- over safety."
In the Lancet study, researchers in the Netherlands surveyed 379 ophthalmologists across the country, and asked them to identify all cases of microbial keratitis that occurred in a three-month period; the type of lens the person used; and the person's wearing pattern -- whether a daily user, keeping the lenses in for fewer than 24 hours, or an extended-wear user who left them in for one to two weeks. Microbial keratitis is an infection of the cornea, which is the outer wall of the eye. Dr. Kam Cheng and his colleagues found that although rigid gas-permeable lens users can be at risk for corneal infections, the risk was more than three times higher for those who wore soft lenses for 24 hours at a time, and almost 20 times higher for those who wore extended-wear soft lenses. The study reported findings similar to those in a 1989 U.S. study -- a fact that the researchers say shows that new contact lens materials have not reduced the number of people contracting this infection. "Since millions of contact lens wearers are at risk, this complication is an important public issue," wrote Cheng and his colleagues in the study.
"I've been doing contact lenses for 43 years and rarely discuss relative risk factors; we simply accept the fact that the lenses are safe; they have been proved safe," says Clarence McEachern, an optometrist practicing in Columbia, S.C., and a former member of the Food and Drug Administration's Ophthalmic Devices Panel. "Years ago we used to think that the health risks with rigid lenses were risky, because they created trauma -- mechanical trauma -- because they took the same kind of plastic you make screwdrivers out of and put it on the eyeball."
Of course, rigid lenses are not made out of tool materials anymore, but they have never reached the same cushy comfort level as the soft. And that's exactly what Suzanne Fleiszig, an associate professor in at the University of California at Berkeley School of Optometry, believes it all comes down to: "Most people don't want to put up with that initial discomfort, so they go straight to the soft lens," she says. "They don't realize the risk."
Most doctors would say many of the problems with infections can be traced to patients who aren't following the proper protocol -- those who are wearing the lenses too long and not cleaning them. But although extended-wear lenses are approved for seven-day use, many optometrists, including the Netherlands researchers, say one of the worst things to do is to sleep with them on.
"Rigid gas-permeable is not safer than soft contact lens; the real issue is that daily use of contact lens -- and that is removing them nightly -- is safer than sleeping with them," says Dr. Anne Sumers, a spokeswoman for the American Academy of Ophthalmology who is in private practice in Ridgewood, N.J. Although extended-wear contacts are FDA-approved for up to six nights, doctors generally don't recommend it. "I tell my patients, after you brush your teeth, take your contacts out," Sumers says.
Rigid contacts are good for most types of vision problems, particularly for astigmatism, but require daily care. With soft lenses, people can wear them to a cocktail party and then put them away for a month without even touching them.
"When a patient comes in and says, 'I want contacts,' the issue is, 'What's your prescription?' And in most cases, we start with the soft lens because they're easier to get used to," Sumers says. She says she warns patients about the risks with contact lenses in general, but not about the soft lens risk per se because she doesn't believe that it's worse than the rigid.
But debating which lens is better may be an issue of the past. Cavanagh says we're on the cusp of the next contact-lens revolution. Within a few years, there will be soft contact lenses that allow more oxygen to reach the cornea (a higher oxygen-transmissible lens), which people will be able to wear for up to 30 days and sleep in; an achievement that he believes will drastically cut down on the rate of infections. (Rigid contact lenses, according to Cavanagh, already allow a lot of oxygen to reach the cornea.) "You're talking about a complete shift of the market, with everything off the shelves and gone." But since we're still a couple of years away, Cavanagh suggests that, though microbial keratitis is rare -- affecting only about four out of 10,000 people -- it's still important to R.S.V.P., as he calls it: look for Redness, Sudden change in Vision and Pain. If that happens, contact your doctor.