Types of sunglasses

Thursday, February 18th, 2010 at 6:14 pm Post in Sunglasses

There are three types of UV rays, namely UVA, UVB and UVC, all of which are located just behind the violet portion of the visible spectrum. UVC rays are blocked by the earth’s atmosphere but UVB rays are quite dangerous. Spending much time outdoors, children with sensitive eyes need more UV protection from sunglasses.

During 10 am and 2 pm in which sun rays are most intensive, sunglasses are necessary to get UV protection. Whether it is overcast or sunny, UV light can go through clouds. Some factors impose a higher risk of UV light on human vision, including sunlamps, tanning beds and parlors, living at high altitudes or near the equator. And people with cataracts, macular degeneration or retinal dystrophies should pay extra attention to UV rays.

Sunglasses are available in various colors and styles. Blue-block sunglasses can keep the wearer away from blue light, which is thought to increase disease-caused eye damage. These blue-blockers are preferred by skiers, hunters, boaters and pilots. Bothersome glare can be cut by either polarized lenses or lenses with anti-reflective coatings.

Mirror-coated lenses can prevent a significant amount of unwanted light from entering the eyes. Applied to the front surface of lenses, these highly reflective coatings are particularly beneficial during activities in bright conditions. The color of mirror coating can also be cosmetic, without any influence on color perception.

Darkest at the top, gradient lenses can protect the eyes against overhead sunlight and allow more light through the bottom half. This feature makes gradient lenses the best choice for driving. Double gradient lenses have two darkest parts at the bottom and the top, while the middle part is lighter. Photochromic lenses change their color in accordance to external UV ray amounts.

For eye safety, impact-resistant lenses are necessary either on the job or during sports. In general, sports eyewear made of special materials is safer than ordinary eyeglasses. Performance sunglasses can even improve the vision.