Welcome to Marin Eye Care

Marin Eye Care: Protecting Your Eyes

Protecting Your Eyes from Everyday Hazards

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

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

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.

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

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.

Contact Lenses

There are three types of contact lenses: hard, soft, and oxygen- (gas) permeable. Each is fashioned out of a slightly different material, requiring different care.

Hard lenses were the first type marketed. According to James Saviola, an optometrist in FDA's division of ophthalmic devices, hard lenses are fashioned from the same material originally used to make airplane windshields. Of the contact lens types, they are best able to correct astigmatism because they form a new front surface to counteract the irregular cornea. It takes several weeks for the wearer to become adjusted to hard lenses, however, and they should be worn according to a schedule for maximum benefit.

Because the material from which hard lenses are made does not admit oxygen to the eye, after a few hours the eye will begin to swell. Hard lens wearers must remove their lenses after about 12 hours of use and rely on eyeglasses for the rest of the day. To overcome this problem, oxygen-permeable lenses were developed. Because these are actually a type of hard lens, the period of adjustment and routine wearing schedules are similar to the break-in period of regular hard lenses.

Soft contact lenses are made of various types of water-absorbing plastics that allow oxygen to reach the eye. They are easier to adjust to than hard contact lenses, usually requiring no more than a week until they are comfortable. They are less likely than hard lenses to dislodge when playing sports, but they are less durable and may need to be replaced every year.

Soft lenses require careful attention to cleaning, rinsing and disinfection. Daily-wear soft contact lenses need to be cleaned daily and, as with hard and oxygen-permeable lenses, must be removed for sleeping. Extended-wear soft contact lenses can be left in the eye while sleeping, but, as mentioned previously, must be removed at least once a week for cleaning.

Educating Yourself

Learn to recognize signs of trouble that can alert you to serious problems:

• red or painful eyes
• sudden changes in vision
• repeated irritation of the eye
• excess secretions from the eyes.

Eye safety requires only a little education and a lot of common sense. Take care of your windows to the world, and they will reward you with all that world's visual delights.

Jessica Auerbach is a writer-editor with the division of consumer affairs in FDA's Center for Devices and Radiological Health.