The Benefits and Downside of UV light
Why is it important? What are the risks?
Intense UV radiation can damage the skin and eyes – that much we know. Yet our bodies simply can’t do without UV light, and we benefit from it in a number of different ways. BETTER VISION explains: What are the different types of UV light? What are the upsides and downsides of UV light? How do we benefit from it? How can it hurt us?
The benefits of UV light
Summer means fun in the sun! For many people, this is the best time of year. They head out to enjoy the great weather, spending time at beaches, parks and pools. When people mention UV light, they often only talk about its damaging qualities – but we benefit from UV radiation as well. UV light impacts numerous metabolic processes in people, plants and animals. But our digital way of life means we’re spending more time indoors and thus don’t see the daylight as much. So it’s even more important to step outside and take part in outdoor activities to make ourselves feel good and stay healthy. All the same, we should ensure that we are sufficiently protected from the sun – that applies to our skin as much as it does to our eyes. UV radiation can damage our eyes in a number of ways – but there are great ways to protect ourselves, too. To ensure you’re fully protected, we recommend wearing either a high-quality pair of sunglasses or clear lenses with an integrated UV filter up to 400 nm.1
The downsides of UV light
Spending a lot of time in the sun means intense radiation. This can damage your skin and eyes if you don’t protect them from the sun and wear good sunglasses with UV protection. Chronic eye damage caused by UV radiation cannot be treated. But what exactly are the negative effects of UV light on our eyes and skin?
Eye damage caused by UV light
When people think of sun protection, the first thing that springs to mind is their skin. But our eyes are also sensitive to UV radiation – not only when the sun is shining but in the shade, too. And not only at noon, but all day, every day. Even on a cloudy day, UV radiation can be as high as 70 to 75% on the ground due to reflection and dispersion.2 Water, for instance, reflects up to 20% of UV radiation, fresh snow roughly 88%, sand up to 25% and a concrete road around 12%.3
In terms of UV protection, the earlier you start, the better – but it’s never too late!
Children’s eyes are particularly sensitive to UV rays. By the time we turn 20, we’ve already been exposed to around half the amount of the UV radiation a 60-year-old has been exposed to. In other words, by age 20, we’ll have absorbed about 40 years’ worth of UV radiation!4
If we don’t protect ourselves, we could end up damaging our eyelids and the skin around our eyes, or even develop one of many other diseases, such as those affecting the cornea. These include conjunctivitis and photokeratitis (AKA ultraviolet keratitis). These terms refer to damage to the cornea caused by strong UV radiation. In continuous intense light, we run the risk of the eye’s lens becoming cloudy, which can lead to premature cataracts. UV radiation is also suspected to cause tumors on the eyelid.
In order to effectively protect both the eyes and the surrounding skin from UV radiation, we recommend wearing both sunglasses or everyday, clear lenses with full UV protection up to 400 nm. This way, you’ll be protected whatever the weather – even on cloudy days.
Here’s a tip for contact lens wearers: while contact lenses with UV protection are available, they don’t protect your sensitive eyelids, particularly the edges. That’s why we recommend you invest in a good pair of sunglasses capable of blocking incidental light.
Damaging effects of UV light on your skin
UV radiation can also damage our skin. We know that excessive tanning outdoors and spending too much time on the tanning bed are responsible for increased rates of skin cancer. And UV exposure has already been identified as the main cause of skin cancer. A major risk is that the eyes are not normally taken into account when people think about sun protection. But in fact, 5–10% of all skin cancer cases involve the eyes.5 To ensure that this sensitive area is protected from UV radiation, we recommend wearing both sunglasses and everyday prescription glasses with full UV protection up to 400 nm. This will also protect the area around the eyes against premature photo aging, which is caused primarily by UV radiation. Common long-term effects of excessive tanning are expanded pores and blood vessels, damage to the connective tissue, blackheads and dry skin. In addition to sunburn and redness, UV light can cause a variety of symptoms that are often collectively referred to as a “sun allergy.” Though not an allergy in the traditional sense, illnesses in this category can generally be traced back to sunlight, and to the UV portion of light in particular. For example, a widespread illness caused by UV radiation is sun eczema. Symptoms typically become evident when we expose our skin to a large amount of sunlight, such as on the first long walk we take when spring arrives. Blisters with redness and itching form on the areas affected. The severity of the symptoms can vary enormously depending on the individual’s skin. Taking certain medications in connection with UV radiation can even elicit a reaction that seems like an allergy.
Acne aestivalis frequently comes up in connection with the damage caused by UV light. The term “acne” is actually misleading, since this isn’t a textbook case of acne – it just has similar symptoms. This reaction is actually a unique form of sun eczema. Acne aestivalis is not only thought to be caused by intense UVA radiation, but also by an allergic reaction to sunscreen. While the exact cause is unknown, UV radiation combined with sunscreen can cause inflammation of the skin’s oil glands.
Tip: In some cases you can prevent acne aestivalis by using special sunscreen (available at specialist retailers) that soothes sensitive skin when applied regularly.
When enjoying the sunshine at the beach, make sure you protect your eyes by wearing high-quality sunglasses with a dark tint and a UV filter up to 400 nm, and regularly apply enough sunscreen to prevent UV skin damage. ZEISS PhotoFusion self-tinting lenses also feature complete UV protection up to 400 nm.
What exactly is UV light? Where does it come from?
The biggest source of UV radiation on Earth comes from the sun. People usually refer to it as “UV light.” In physics terms, however, this is incorrect as it’s not light per se, but in fact radiation. While light and radiation are both made up of electromagnetic waves and are part of what’s known as the electromagnetic spectrum, where all kinds of these wavelengths are brought together, there is a difference between the two. Light is something we are capable of perceiving. “Radiation” is the invisible part of the wavelength spectrum that includes infrared, X-rays, microwaves and UV rays.
The different types of UV light
There are different types of UV rays, and each one affects the body in a different way. A distinction is made between UV-A, UV-B and UV-C radiation.
(100 to 280 nm) barely penetrates our skin and retina, but a large dose can still cause red skin and painful eye inflammation. UVC radiation also destroys cells, which is why it is used in artificial disinfectant. But you don’t need to take any special precautions against UV-C radiation, because the ozone layer absorbs it completely – even in those areas where the ozone layer has been damaged.
UV-A radiation/UV-B radiation
UV-A radiation (315 to 400 nm) and UV-B radiation (280 and 315 nm) have a similar effect on the body. They can trigger acute medium- and long-term damage:
Enjoyed in moderation, UV-A and UV-B rays tan the skin, but high doses can cause redness, rashes, allergies or sunburn, for instance on the eyelids. UV-B radiation can cause acute photokeratitis (AKA UV keratitis), a type of damage to the cornea.
UV radiation may lead to conjunctivitis, also known as “pinkeye,” which is inflammation of the thin clear tissue that lies over the white part of the eye and lines the inside of the eyelid.
UV-A radiation can speed up skin aging (or photo aging) and weaken our ability to see. It increases the risk of early-onset age-related macular degeneration (AMD). UV-A radiation is also suspected of causing cancer of the eyelid, triggering dangerous changes to the cornea that lead to cataracts. Up to 48% of all cases of blindness around the world are caused by cataracts – and in around 20%, UV radiation is responsible for causing or exacerbating the disease. There are also indicators that UV-A and UV-B radiation could be partially responsible for melanoma. Tissue growth on the conjunctiva and at the edge of the cornea (pterygium conjunctivae) and pinguecula are typical symptoms of excessive UV exposure.
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1 UVA radiation can reach up to 400 nm; International Commission on Non-Ionizing Radiation Protection (ICNIRP), American Conference of Governmental and Industrial Hygienists (ACGIH), ISO 21348 (definitions of Solar Irradiance Spectral Categories), also applied in Australian Sunlens Standard AS/NZS 1067:2003 and definition adopted by the World Health Organization (WHO)
2 UV index by time and season: http://www.who.int/uv/publications/globalindex/en/ - Calbo, J., & González, J. A. (2005). Empirical studies of cloud effects on UV radiation: A review. Reviews of Geophysics, 43(2).
Sliney DH. Physical factors in cataractogenesis: ambient ultraviolet radiation and temperature. Invest Ophthalmol Vis Sci. 1986 May;27(5):781-90.
4 18. Green AC, Wallingford SC, McBride, P. Childhood exposure to ultraviolet radiation and harmful skin effects: Epidemiological evidence. Prog Biophys Mol Biol. 2011 Dec: 107(3): 349-355
5 Cook BE Jr, Bartley GB. Treatment options and future prospects for the management of eyelid malignancies: an evidence-based update. Ophthalmology 2001 Nov; 108(11):2088-98. - Abraham J, Jabaley M, Hoopes JE. Basal cell carcinoma of the medial canthal region. Am J Surg 1973; Oct; 126(4):492-5.