Scoping Out Sunglasses
You may think we wear sunglasses for comfort and fashion. But here's another important
reason to wear sunglasses—to protect the health of your eyes.
If you spend long hours in the sun without protection, you increase your exposure
to ultraviolet (UV) rays. UV is an invisible form of radiation from sunlight. Overexposure
to UV-A and UV-B radiation causes damage to the skin and eyes. You can damage the
surface of your eyes in the same way you can get sunburned—with just 1 exposure to
extremely bright sunlight reflected off sand, snow, or water. Exposure to sunlight
over years can lead to vision loss from cataracts or macular degeneration.
Conditions that put eyes at risk
According to the American Academy of Ophthalmology (AAO) and the American Optometric
Association (AOA), these are conditions that put the eyes of adults and children at
Surfaces like snow, sand, water, and concrete that reflect UV rays.
High altitudes or low latitudes. Exposure to UV rays is higher in the mountains or
closer to the equator like in the Caribbean.
Time of day. UV radiation is usually at its highest from 10 a.m. to 4 p.m. As a rule
of thumb, check your shadow. If it's shorter than you, UV radiation is at a higher
intensity. If it is longer, UV radiation is at a lower intensity.
Time of year. UV radiation is higher in the spring and summer, or May to August in
the northern hemisphere, and lower in the fall and winter.
Safety steps to take
Protect your eyes:
Don’t look directly at the sun. The AAO and AOA say that damage to eyes from looking
directly at the sun during an eclipse is from thermal rays of the sun, not UV radiation.
Sunglasses won’t protect your eyes. Don’t look directly at an eclipse.
Wear sunglasses that protect your eyes from UVA and UVB rays when you are outside.
Wear them even on cloudy days. Ask your optometrist or ophthalmologist for advice
on sunglasses that offer a safe level of protection.
Wear a hat to provide additional protection for not only your eyes, but also your
skin. Wear one even on cloudy days.
These safety measures are especially important for people who have lighter skin or
light-colored eyes, and for people who take medicines that increase the skin’s and
eyes' sensitivity to sunlight. These medicines include tetracycline, doxycycline,
allopurinol, sulfa medicines, birth control pills, diuretics, phenothiazine, and psoralens.
What features should you look for?
The AAO and AOA advise against buying sunglasses that promise to block UV radiation
but don’t say how much is blocked. If they don’t block 100% of UV radiation or say
UV absorption up to 400nm, don't buy them.
Either plastic or glass lenses can soak up UV light, but the protection of either
can be improved by the addition of a clear UV coating. According to the AAO and AOA,
mirror coating and gradient tinting of lenses don't offer UV protection. The color
and degree of darkness of lenses don't mean the lenses can block UV rays. Polarized
lenses block glare, but offer no UV protection. Photochromic lenses, or lenses that
change from light to dark when exposed to UV rays, may offer protection. Wraparound
sunglasses keep light from shining on your eyes from the sides, offering more protection.
Polycarbonate lenses offer 99% UV protection.
For comfort, sunglasses should be free of distortion and imperfection. Look through
the glasses at arm's length and move them slowly across, up and down over a square
pattern like a floor tile. If the lines sway or wiggle, the lenses are imperfect.
You also should check lenses to make sure the color is exactly the same throughout.
If you play sports, consider getting special lenses made from polycarbonate plastic
that protects them from breaking. Also, get them with a coating that protects them