Our sun provides us light, energy, and heat. It is nearly one million miles in diameter, almost 100x times larger than the earth, and is about 93 million miles away from the earth, causing its light to take about 8 minutes to reach the earth’s surface. It is also the most powerful source of ultraviolet (UV) rays to life on earth.
UV rays are found on the visible light spectrum ranging from 100 – 400 nanometers (nm). We categorize UV into three separate groups: UVA, UVB, and UVC. Fortunately, we do not have to worry about UVC as all of these rays are absorbed by the ozone layer and atmosphere, never making it to earth's surface.
However, some of the UVB rays and all the UVA rays will penetrate the atmosphere and make it to earth. These are the rays we focus on protecting. UV is known to have damaging effects to not only our skin but our eyes as well. Overexposure to UV can lead to cataracts (cloudiness of the crystalline lens), macular degeneration (permanent vision loss), photokeratitis (temporary vision loss), pterygiums (growths on the eye) or even skin cancer.
Many of our lens materials have UV protection built into them. Standard plastic (CR-39) and glass lenses are the only lenses that do not have full UV protection built into the monomer of the lens. Many of our lens treatments also have UV protection, like our Sensity™ Family of photochromic lenses and our Coppertone™ polarized lenses.