You may know that it is important to wear sunglasses in the summer to protect your eyes, but do you know why? The answer has to do with exposure to the ultraviolet (UV) rays in sunlight.
Light radiates from the sun in waves. Like ocean waves, light waves have a measurable length, height, and duration or frequency. Scientists measure light wavelengths in nanometers (nm). The various wavelengths of light cause the light to act in different ways. Visible light has wavelengths between 400 and 700 nm. UV light has a wavelength range of 100 to 400 nm. According to the World Health Organization (WHO), the shorter the wavelength, the more harmful the radiation.
There are three main bands of UV light:
- UVA (315-400 nm)
- UVB (280-315 nm)
- UVC (100-280 nm)
The atmosphere burns up most of the UVA rays before they reach earth but UVA rays can penetrate into the deeper layers of skin to cause aging and wrinkling. UVB rays cause delayed tanning and sunburn, enhances skin aging, and promotes the development of skin cancer, but these rays cannot penetrate beyond the superficial layers of skin. Both UVA and UVB can have long-term adverse effects on the eyes and vision.
UV radiation from natural sunlight – and some types of artificial indoor light – can damage tissues in the eyes, particularly when exposure continues over a lifetime. Years of exposure to UVB light can cause protein to clump and thicken in the lens of the eye, which clouds the lens and prevents light from passing through it; doctors refer to these clumps as cataracts. Too much time in the sun can speed the development of cataracts; wearing sunglasses that offer UV protection can help reduce your risk of cataracts.
UV light can increase the risk for macular degeneration, which is a leading cause of vision loss in people 50 years or older. Macular degeneration affects the light-sensitive tissue lining the inside of the eye. Exposure to UV rays can also increase the risk for eye cancer, growths on the eye, and snow blindness, a form of photokeratitis or “sunburn on the eye.”
Sunglasses can protect your eyes from dangerous UV rays, but only if you wear sunglasses that block most, if not all, harmful UVA and UVB rays. For more information about why you should wear sunglasses to protect your eyes during summer, consult with your eye care professionals at Illinois Eye Center and schedule your appointment online today.