- How it Works
December 6, 2017
Most people are aware that ultraviolet rays from the sun can lead to skin cancer and accelerate aging (loss of elastin, premature wrinkling or sunspots), although not everyone heeds these warnings. Far less people seem to be aware of the damaging effects of UV rays on the eyes- especially during the winter months. Pterygium, a growth that starts on the white of the eye (sclera) can also impact the cornea. It is tied to UV ray exposure and can eventually block vision. In addition, sun exposure can result in eyelid skin cancers, including basal cell carcinoma, squamous cell carcinoma and melanoma.
The two different types of rays emitted from the sun, UV-A and UV-B, are both damaging to the eyes, with some distinctive differences. Most UV-B rays are absorbed by the front part of the eye (cornea and lens), thereby causing more overall damage to the eyes than UV-A rays. During winter months, despite the cold, the snow reflects up to 90% of these UV rays!
UV-A Rays: Hurts central vision by damaging the macula, a part of the retina at the back of the eye. Exposure may lead to macular degeneration, the leading cause of vision loss, affecting more than 10 million Americans.
UV-B Rays: UV rays, especially UV-B rays, are linked to formation of a minimum of 10% of cataracts, a clouding of the eye’s lens. A 2014 study showed UV light can damage lens proteins in a distinctive manner typically seen in cataracts and cells damaged by oxidative stress. The study also found a natural antioxidant in the eye and other tissues, called glutathione, offered little protection against the damaging effects of UV light. Corneal sunburn (photokeratitis) results from intense, short-term exposure to UV-B rays. A day at the beach or skiing without proper eye protection may lead to this painful, temporary cause of vision loss.
People and athletes who spend a lot of time outside for extended periods without proper eye protection are at greater risk of UV damage. Light colored eyes may increase the risk of certain UV-related eye diseases (e.g. eye cancer), although brown eyes are more susceptible to cataracts. Some studies show people with specific eye diseases (e.g. retinal dystrophy) may be at greater risk of developing UV-related sun damage. And if you are taking any drugs that increase skin sensitivity to light, this also impacts your eyes.
Wearing proper eye protection is key to preventing eye damage, any time of the year. Hundreds of different styles, colors, and price ranges can make choosing proper sunglasses a little challenging. Once you know what to look for, buying sunglasses is far easier. For starters, sunglasses should absorb and block 100% of UVA and UVB light, so look for this sticker on the lens. They should be large enough to shield the eyes, eyelids, and surrounding areas.
Do consider size – wraparound styles with a comfortable, close fit and UV- protective side shields are ideal
Do look for durability and impact resistance
Do buy within your budget-– higher cost does not equate to better UV protection
Don’t assume darker lenses afford greater UV protection – lens color has nothing to do with this
Don’t buy sunglasses without a 100% UV protection sticker
Don’t base your decision on the “cool factor” alone
Normal sunglasses provide basic protection against both vertical and horizontal UV rays, but don’t reduce glare from reflected horizontal rays. Polarized glasses have a built-in, laminated filter. While vertical light rays pass through, polarizing filters block nearly all horizontal rays, thereby preventing glare. Polarizing glasses benefit anyone who spends a lot of time outside, especially boating enthusiasts, fisherman, and hunters. These glasses can help reduce eye strain and fatigue when driving, particularly in the summer when horizontal rays of light are continually refracted from the road back through the car windshield. Polarized sunglasses are generally more expensive and not all of them protect against harmful UV rays, so look for the sticker, as mentioned above. They aren’t recommended for skiers, pilots, operators of heavy machinery or ATV use due to potential image distortions.
Photochromic or transition” lenses darken in the sun then lighten when you go inside. The earliest glass photochromic lenses used silver chloride or silver halide, which reacted to UV light by darkening. Today, most transition lenses rely on proprietary dyes that undergo chemical changes, causing lenses to darken when exposed to UV light. Prescription transition lenses prevent forgetting sunglasses when you go outside, thereby providing continuous UV protection. Photochromic lenses are available in shatter-resistant styles, bifocals, progressives and more. Be aware that some auto glass has built-in UV protection, which can prevent photochromic lenses from darkening. If your auto glass has this feature, ask for lenses designed to remedy the problem.
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