Protecting Your Eyes from Everyday Hazards

by Food and Drug Administration (FDA)

Eyes are said to be the windows to our souls, but they are also windows to the world that need to be kept clear and in good working order. Eyes need protection from many environmental assaults (including bacteria or other contaminants), ultraviolet light, and foreign objects ranging from flying sparks in a chemistry lab to an errant racquetball on the court.

Contaminants and Eye Disease

Severe eye infections among people improperly using homemade saline solutions for soft contact lenses have been reported to the Food and Drug Administration over the last few years. In January 1989 the agency sent 50,000 letters to eye-care practitioners nationwide to warn them of this problem. Certain species of Acanthamoeba (a kind of parasite) were present in homemade solutions because the prepared solutions were not sterile. A study by the Centers for Disease Control in Atlanta found that people were not using the product correctly. For example, they were using the solutions as a rinse after heat disinfection, or in eye drop form, thus possibly introducing a contaminated solution into the eye.

In the alert, FDA recommends that users of homemade saline:

• Use homemade saline solutions only before or during heat disinfection.
• Never use after heat disinfection — for example, for cleaning before putting in eyes.
• Never use with chemical or hydrogen peroxide disinfection.
• Never use directly in the eye or as a wetting solution.
• Prepare fresh saline solution daily.
• Sterilize solution bottle with boiling water at least once a week.
• Avoid swimming with contact lenses in place because of danger of bacterial contamination from pool or sea water.

Recently, FDA investigated reports of corneal ulcers with long-term use of extended-wear contact lenses. Corneal ulcers can cause scarring to the cornea, leading to vision loss, including partial or complete blindness. Recent studies show that wearing either daily- or extended-wear lenses for too long increases the risk of corneal ulcers, as does smoking. While the overall risk of corneal ulcers is small, the relative risk of extended-wear to daily-wear is approximately 5 to 1. Originally designed and marketed for use from 1 to 30 days, these lenses are now being recommended only for week-long wear at the most.

Ultraviolet Light and Eye Damage

Not only must our eyes be protected from disease, but also from ultraviolet light. UV light emanates from the sun naturally or from special lamps (such as sun lamps). There are three types of ultraviolet light: UVA, UVB and UVC.

UVC light is normally screened out by the ozone layer and so far does not present an immediate threat. UVB light can cause the greatest eye damage. Overexposure to intense UVB light can damage the cornea, producing a painful condition known as photokeratitis. While recovery occurs over several days, the eye often must be bandaged. Many scientists think there is a link between prolonged exposure to UVB light and the formation of lens cataracts. Some studies also show a possible link between UVA light and cataract formation (see "Lifting the Clouds of Cataracts" in the December 1989-January 1990 FDA Consumer). Because UVA light can reach the retina, researchers are studying whether long-term exposure may be related to loss of vision in old age.

Sunglasses offer the best eye protection from UV light, better than visor hats or parasols. To help consumers make the most informed choice of eye wear to protect them from ultraviolet exposure, FDA and the Sunglass Association of America have developed a labeling agreement, under which sunglass labels will indicate the "use category" of the product. The categories, representing different levels of protection appropriate for different outdoor environments, are:

Cosmetic (lightly tinted lenses for use in non-harsh sunlight) — Screens at least 70 percent of UVB, 20 percent of UVA, and less than 60 percent of visible light.

General Purpose (medium to dark tinted lenses for use in most outdoor activities, such as boating, flying and hiking) — Screens at least 95 percent of UVB, 60 percent of UVA, and 60 to 92 percent of visible light.

Special Purpose (recommended for use in very bright environments, such as when skiing, mountain climbing, or at tropical beaches) — Screens at least 99 percent of UVB, at least 60 percent of UVA, and 20 to 97 percent of visible light.

In addition, the agreement encourages manufacturers to list the actual amount of UVA and UVB the product blocks. If this information doesn't appear on the label, consumers might want to check with the manufacturers to find out how much UVA and UVB light is screened out by these lenses. Sunglasses should not be worn when it's dark because they compromise night vision. That also goes for tinted contact lenses.

Under the agreement, manufacturers will provide point-of-sale brochures explaining concerns about UV light and how to best take advantage of the information provided in the labels.

Protective sunglasses, however, are not sufficient for people exposed to UV lamps, such as those found in tanning booths. FDA requires tanning salons to make special protective goggles available to their customers.

Foreign Objects

To help protect against damage from foreign objects striking or entering the eye, FDA requires that all eyeglass lenses be "impact resistant," although not necessarily shatterproof. Impact resistance is measured by the "drop ball test" — dropping a 5/8-inch steel ball weighing approximately one-half ounce from a height of 50 inches onto the horizontal upper surface of the lens. To meet FDA regulations, the lens must not crack through all thicknesses, nor may any pieces chip off, nor any crack run the diameter of the lens. This requirement holds true for glass, plastic and laminated glass lenses. Industrial safety glasses are not regulated by FDA, but by the Occupational Safety and Health Administration, which has additional requirements for impact resistance for those industrial uses.

Cosmetics should be considered foreign objects capable of causing eye irritation. Contact lens wearers should insert their lenses before applying makeup, especially liquid foundation. According to a two-part report published in the May and June 1980 issues of Consumer Reports, mascara should be replaced three or four times a year due to the possibility of bacterial contamination. The wands come into contact with airborne bacteria and become contaminated, which can cause eye infections. Hair spray should not be used once contact lenses have been inserted; the spray clings to lenses and cannot be removed.

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.