MY brother, Jeff, depends on extended-wear contact lenses that stay in his eyes, day and night, for one or two weeks. Then he removes them for an overnight cleaning and puts them back in his eyes for another week or so, replacing them with a new pair when they begin to feel uncomfortable.
My son Lorin and his wife, Angelica, leave their disposable lenses in their eyes for seven days and six nights. Every Saturday night they remove and discard them and the next day replace them with a new pair.
My daughter-in-law Kris also wears disposable lenses. But she removes them nightly, giving her eyes a rest and the lenses a cleaning, and she replaces them with a new pair every two weeks.
The time-honored safety of spectacles and the recent advent of laser surgery that eliminates the need for corrective lenses by permanently changing the shape of the cornea have done little to squelch the growing popularity of contact lenses, especially among people under 40. Attracted by improvements in design and comfort made more than a decade ago, some 30 million Americans now wear tiny circles of plastic or silicone in their eyes to help them see better. Experts predict that by the turn of the century half of all people needing corrective lenses will be wearing contacts.
Unfortunately, a frightening proportion of contact lens wearers fail to follow standard safety precautions to prevent eye ulcers and infections that could scar the cornea and permanently impair their vision. They leave their lenses in too long, are careless about cleaning them, fail to discard them when they should and, when rushed, wet them with nonsterile fluids like saliva and tap water.
The contact lens industry, recognizing the human tendency to take risks for the sake of convenience and savings, has through the years introduced improvements that make lens wearing safer and simpler without a sharp increase in cost.
A Cafeteria of Contacts
The original hard lenses that had to be removed nightly and took weeks to get used to (many people never could) have yielded to more comfortable and convenient alternatives. There are rigid gas-permeable lenses that are removed nightly but are less irritating to the eyes because they are more flexible and allow more oxygen to penetrate. Like the original hard lenses, these require a daily cleaning and disinfecting process that if not properly followed can increase the risk of mishaps.
Most people now opt for soft disposable lenses that do not require elaborate cleansing. These are either removed nightly and placed in a disinfecting solution or worn for a week and then discarded, depending on the product.
For those fitted with extended-wear lenses, the Food and Drug Administration and most eye doctors now recommend that the lenses be left in for no more than seven days and six nights, then removed on the seventh night to give the eyes a chance to ''breathe.'' The cornea on which a contact lens sits has no blood supply and thus depends on oxygen from the air. When the cornea is covered by a lens, its access to air is reduced, which can result in serious complications.
Contact lenses that promise to be even more convenient and possibly safer are now in the research pipeline awaiting approval from the F.D.A. for wide-scale testing. These lenses are designed to be worn continuously for 30 days and nights before being removed and perhaps discarded. They are made of materials that permit freer passage of oxygen to the cornea.
Dr. W. Dwight Cavanagh, professor of ophthalmology at the University of Texas Southwestern Medical Center in Dallas, has been studying the safety of 30-day lenses in animals and people. He reported that these highly permeable lenses allowed the cornea to get enough oxygen to nearly eliminate the possibility that vision-damaging bacteria could gain a foothold.
But studies in laboratory animals by Dr. Suzanne Fleiszig, a microbiologist at the School of Optometry of the University of California at Berkeley, suggested that even with a healthy oxygen supply, a cornea covered by a long-wear lens could become infected by bacteria that become trapped under it.
In an interview, Dr. Fleiszig pointed out that when there is a contact lens in the eye, the natural sweeping action of a blink, which usually occurs every 10 seconds, is unable to clear away bacteria that may lodge under a lens, giving the organisms a chance to infect corneal cells if the lens remains in place for 30 days. Because such infections are rare when proper lens care techniques are used, Dr. Fleiszig's concerns probably cannot be tested until 30-day lenses are approved for marketing and become widely used.
Safe Lens Wear
Studies have shown that the leading hazards of extended-wear lenses now available, corneal ulcers and infections, are far more likely to occur if lenses are left in the eye too long. Even with gas-permeable lenses, the cornea does not get quite enough oxygen to prevent infections that could cause permanent scarring and vision loss. Shortcuts commonly taken by lens wearers can increase the risk of serious complications.
My son, for example, had been told that if a lens popped out, he could wet it with saliva or tap water and put it back in his eye. This is absolutely wrong. There is no better way to introduce an infection than to wet a lens with anything except a sterile lens solution. Even distilled water is risky; it lack minerals but not necessarily bacteria. Lenses should be wetted only with commercially prepared saline without preservatives.
Dr. Cavanagh suggests that lens wearers carry a lens case containing disinfecting solution that is replaced daily. Hands should always be washed before handling a lens.
Then there is the matter of how long the lenses are left in. Daily-wear lenses should not be left in overnight. My brother's lenses were meant to be worn for one week, then discarded. By extending their use, he is increasing the risk of infection as well as less than clear vision because soft lenses can become coated with proteins even when they are cleaned periodically with an enzyme solution.
Warning Signs
If your eyes become red, sore or painful, remove your lenses right away. Any of these symptoms should prompt a visit to an eye doctor without delay: redness, irritation or blurred vision that does not subside when you remove your lenses, rinse them with sterile solution and reinsert them; excessive tearing, pain or light sensitivity.
https://www.nytimes.com/1998/02/17/science/personal-health-safety-rules-for-contact-lenses.html?rref=collection%2Ftimestopic%2FContact%20Lenses&action=click&contentCollection=health®ion=stream&module=stream_unit&version=latest&contentPlacement=72&pgtype=collection
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