The Hazards of UV Rays Reflected Off Snow
Inuit snow goggles have been worn by the native people of the Arctic for centuries to prevent snow blindness. Often made from the ivory of walrus or caribou antler, a thin slit is cut across both in order to reduce the amount of light and glare coming in and to improve visual acuity. During the twentieth century, the Inuit began using wood as it became more plentiful, but continued to add soot to the inside in order to cut down on glare. The Inuit were keenly aware of the condition, caused by the intensebright light reflected back fromthe snow.
The U.S. Army’s “Arctic Survival Manual” from World War II even warns soldiers about the effects. “The snow goggles in your kit will protect your eyes against the glare. If they have been lost or broken, you can fashion a pair of Eskimo-type snow shields from a scrap of wood about six inches long and an inch wide by burning holes or slits through it at eye width.” The men of the doomed Franklin Expedition even used fine screens to block some of the glare.
Fresh snow is known to reflect 80-85% of UV light, and the sensitive components of the eye are not able to combat the effects of continuous exposure. Even sea foam reflects only about 25% of the light. Snow blindness, also known as photokeratitis or ultraviolet keratitis, during the winter is not as well understood by many urbanized people south of the Artic Circle, but many optometrists and ophthalmologists have been warning patients about the hazards of this issue.
When driving even short distances, the continuous bright glare can become a problem if large, polarized sunglasses are not worn. Polarizing is effective at reducing both UV and glare by as much as 99%.
Both the British Special Air Service and the ancient Egyptians blackened the skin beneath the eyes with charcoal, reducing reflection. During winter, readers should consider sunglasses that also wrap around and cover the sides, prevent UV light from entering. The hazard comes when either driving directly into sunlight or if light reflects off of another vehicle on the road, temporarily blinding the driver.
- increased tearing
- constricted pupils
- twitching eyelids
- discomfort from bright lights
- painful feeling like sand in the eyes
Unfortunately, these symptoms may not appear for several hours, too late to prevent it. Over time, people may also notice fatigue, headaches, stress, and lost performance or reaction times. Susan Taub, M.D., of the Better Vision Institute warns that snow blindness, "can damage the cornea for up to a week, cause eye pain, extreme sensitivity to light and the sensation of having sand in your eye." Sunburn of the cornea and conjunctiva (the sclera, or whites of the eyes) can also be painful and irritating. The sclera also plays a critical function keeping
microbes out of the eye and preventing infection. Even the tears themselves wash dust and other contaminants out of the eyes in order to preserve a clean surface.
A similar condition, called “arc eye” occurs when welders do not use proper eye protection. The symptoms are similar, but the effects may be permanent resulting in lost or reduced eye sight. Hypertension, an upset circadian rhythm, and other problems can result from the upregulation of adrenaline, akin to the fight or flight response. This increased stress can then contribute to vasoconstriction, which is a major cause of erectile dysfunction, and an out-of-sync melatonin rhythm, which can contribute to insomnia and sleep deprivation.
Heeling may occur in one to three days, but the condition can still interfere with day to day activities, especially driving. Avoiding daylight, removing contact lenses, and not rubbing the eyes can help with the healing process.
In addition to wearing sunglasses, Vision Council of America also advises drivers to keep the sun visor down, leave extra distance to the vehicle ahead, keeping the windshield clean, and avoiding high gloss cleaners for the dash board. Even selecting routes with tall trees and buildings, avoiding large snow drifts, and taking breaks to allow the eyes to recover are advised by experts.
Even under overcast conditions, experts warn, large snow drifts and snow fields can reflect enough UV light back into the eyes to cause this condition. Drivers considering long trips especially should consider oversized polarized sunglasses to protect their retina, sensitive cornea, sclera, and other critical components in the eyes.
Please note: In-office, Optometric Vision therapy, under the direction of a Behavioral Optometrist using prisms, filters and lenses, as used with our patients, is far more effective than home-based therapy.