General Knowledge About UV Radiation And Answers To Commonly Asked Questions From Patients
We always emphasize wearing sunglasses that fully protect your eyes from harmful rays of the sun. With the exception of Ultra Violet (UV) radiation transmitted from man-made devices like tanning beds and sun lamps (which require dedicated eye protection frames) most of the UV radiation that we are exposed to comes from the sun. Its majority is UVA (95% of radiation reaching earth 315-400 nanometers) and the rest is UVB (5%, 280-315 nanometers). All eye care professionals know that with time UVA causes wrinkles which is a manifestation of aging, UVB causes sunburns, and UVC (100- 280 nanometers, practically filtered by the Ozone layer) causes cancer. Here are a few answers to questions we receive on daily basis in our offices as eye care professionals:
Is UV exposure constant throughout the year and days?
The strength of UV transmitted by the sun is strongest between 10 am and 4 pm during the day, during spring and summer, with the altitude as we go up in the mountains and with elevation, as we get closer to the earth’s equator, and from reflected surfaces like snow and sea. Equatorial regions are exposed to strong UV radiation all year long and clouds merely affect or filter it.
What is the UV index and how to interpret it?
The UV Index is an Index developed by the US National Weather Service and the Environmental Protection Agency (EPA) to give you an idea on any day about the strength of UV light in your area. It is reported on a scale from 1 to 11+. Higher UV Index numbers mean a greater risk of exposure to UV rays and a greater chance of getting sunburns leading to skin damage and increasing the long-term risk of skin cancer.
Ways to protect ourselves from UV radiation?
The best way to limit exposure to UV is by staying in the shade and wearing UV protective cloth and sunglasses even when inside vehicles. Sun-protective clothes may have a label indicating the level of radiation protection they provide noted by UV protection factor (UPF) value from 15 to 50+. The higher the UPF, the higher the protection from UV rays. Moreover, the dark color fabric protects the skin more than light color or see-through cloth. However, when it comes to sunglasses darker lens does not necessarily provide better protection.
Do affordable Sunglasses provide appropriate protection?
The advances in technology enabled sunglasses manufacturers to produce UV protection lenses at low prices. A general rule is that designer sunglasses and known brands of sunglasses meet the required norms and standards for UV protection. Lens specifications and UV protection information are provided on a leaflet with every pair of sunglasses. Lenses with UV 400 protection block wavelengths up to 400 nanometers and screen out 75% to 90% of visible light from the sun providing full protection against UVA and UVB.
How Long Do Sunglasses Last?
It has been proven by research conducted by a Brazilian researcher out of the University of Sao Paolo that as time goes by, sunglasses lenses become worn down by sun exposure and can cause long-term damage to your eyes and vision. Therefore, sunglasses should be replaced every two years to rest assured that they provide adequate protection against ultraviolet rays that may damage your eyes.
Are Children also affected by UV radiation?
Children are more sensitive than adults to getting eye damage and because their crystallin is more transparent than adults UV rays reach their retina at a higher percentage. The damage isn’t relevant until after 40 so wearing sunglasses at younger ages is mandatory to ensure they are preventing permanent damages that show up later in life.
What are the possible damages caused by UV exposure?
Besides damages to the skin covering the orbit area, exposure to UV radiation over the years increases the risk of developing eye conditions that include macular degeneration, cataracts, and photokeratitis. Wearing proper sunglasses not only reduces the risk but also delays cataracts from occurring.