More about sunglasses

Glare Reduction
Outdoor enthusiasts and sports-minded people are the most likely to know about the advantages of polarized sunglasses, photochromic lenses and mirrored coating. These are the three most common methods used to reduce glare and reflect bright light outdoors. Avid sports enthusiasts are not the only people who can benefit from these types of lenses. The popularity, availability and versatility of these lenses are increasing dramatically. IN addition to being worn by skiers, golfers, bikers, fisherman and joggers, they can be beneficial to drivers and general users.

Polarization
Horizontal surfaces, such as a paved road, reflect most of the glare that interferes with vision. When light waves reflect off of a surface, they are polarized to equal the angle of that surface. An extremely horizontal surface such as a lake will produce a lot of horizontal polarized light. Polarized lenses in sunglasses work to reduce glare by allowing only vertically polarized light to enter the lens. The lens absorbs all other directions of light.

A chemical film is the most common method of making polarized filters. The film is applied to the lens during the manufacturing process. It is important to note, however, that the goal of polarization is to reduce glare, not to provide ultraviolet protection. Polarization is distinguishable from sunglass tints, in that they have colored coating on the lenses to filter out various light wavelengths.

Polarized lenses are available for bifocals, progressive, photochromic, and single-vision lenses. Thus, whether you spend time on the water, ski slopes, mountain trails or in your car, polarized sunglasses are an excellent add-on to your sunglasses.

Photochromic Lenses
Photochromic lenses are ideal for people who do not want to switch between prescription eyeglasses and prescription sunglasses. They provide the convenience of having a pair of sunglasses and transparent glasses in one pair of lenses. These lenses have millions of light absorbing molecules. The molecules are transparent in artificial light, which is free of UV rays. When exposed to UV rays from natural sunlight, however, the molecules undergo a chemical process, causing them to absorb light and to darken. These light sensitive lenses darken automatically after approximately 30 seconds of natural light and lighten approximately 5 minutes of artificial light. Although photochromic lenses are acceptable for everyday use, polarized lenses are a better alternative for high glare sports such as boating or skiing.

One drawback to wearing photochromic lenses, however, is that the windows and windshield of most modern care have a factory standard UV blocking coating, the lenses will not darken in the car unless the windows are rolled down.

Mirrored Coatings
To reduce glare, a mirrored coating works to reflect bright light. It reduces their amount of visible light that reaches the eye, but it does not block UV light. The mirrored coating is made by bonding a thin layer of vaporized metal to the surface of the lens. The coatings are available in a variety of fashionable colors.

The Basics of Sunglasses
Sunglasses are now available in more styles, brands, materials and colors than ever before. Today’s sunglasses are both functional and fun. Sunglasses can be worn as a fashion accessory to compliment a “look”, give a greater visual performance and comfort outdoors, and offer protection against the elements. Whatever reason you wear sunglasses, all sunglasses should improve your visibility against bright light and glare, and protect your eyes against ultraviolet radiation.

Importance of UV Protection
The most common misconception is that the darker the lens, the higher the UV protection. However, the darkness of the lens has little to do with protecting our eyes from potentially harmful UV radiation. In fact, dark lenses without UV protection can do more harm because the pupils dilate in very dim conditions, allowing more UV rays to enter the eye. The cornea, lens and retina are all vulnerable to UV rays and research shows that continuous exposure to UV light contributes to the development of cataracts or macular degeneration and can cause a form of corneal sunburn called photokeratitis. Consequently, it is important that the sunglasses we wear protect us against UV rays. Proper UV absorption is either an integral part of the lens material or must be added as a coating on the lens.

Inexpensive sunglasses are available from retail stores and street-side vendors, especially in the summer. Knowing the level of protection or the optical quality of these sunglasses is not always possible at the point of purchase. Your Eyecare professional will ensure you are getting the proper sun product that meets your specific needs.

Shades and Tints
The varieties of lens tints available today are staggering and can be confusing. The importance of color choice depends on the specific “sun” need. The traditional greys, browns, and greens provide specific benefits such as, color neutrality, color contrast and eye comfort. Amber, yellow, orange, and red filters can increase depth perception and color contrast by absorbing blue and green wavelengths. These colors are beneficial for low vision conditions like cataracts, macular degeneration, and glaucoma. The pinks, blues and violets are fashion colors that project a fashion trend, mood or are just fun to wear. Some manufacturers provide tints that are specific to sports activities such as golf and tennis. These lenses increase contrast and enhance colors such as the green of the golf course or the yellow of a tennis ball. Check with your Eyecare professional to ensure you are wearing the right tint and color density for your needs.

Tints
Pink tints are useful for bright indoor light protection, but have little value outdoors. They are frequently used for cosmetic reasons because of the flattering effects to some skin tones. Pink lenses are a fashion tint that can add fun and pizzazz to your eyeglasses.

Grey lenses provide the best vision clarity and help to keep colors neutral. Depending on the density of color, grey tints can offer protection against sun and glare.

Some amber or brown tinted lenses are called “blue blockers”, because they work on blocking out the blue lights of the visible spectrum. They tend not to interfere with vision and work best in hazy weather conditions or at dusk by better defining the terrain.

Yellow tints are a favorite with skiers and skeet shooters because they provide excellent depth perception and low light contrast. Yellow tints also work well at night and in foggy conditions.

Amber, yellow, orange, and red filters can increase depth perception and color contrast by absorbing blue and green wavelengths. The colors are beneficial for low vision problems like cataracts, macular degeneration, and glaucoma.

Ultraviolet Hazards
Ultraviolet rays carry more energy that do visible light rays. Thus the eye has a greater risk of damage from absorbing UV radiation than from absorbing other forms of visible light. Two types of UV rays reach the earth’s surface: UV-A and UV-B rays are the rays emitted from the sun that contribute to premature aging and they are present year round. They contribute to early wrinkling of the skin, the development of cataracts and the progression of age-related macular degeneration. UV-B rays are the rays that cause skin cancers, cataracts and photokeratitis, or sunburn of the eye. These rays are stronger during the summer months. Most of the damage caused to the eyes by UV-A and UV-B rays occurs gradually and is irreversible. Sensitivity to UV rays varies from person to person. Certain prescriptions and over the counter drugs might increase sensitivity.

Sunglasses that block UV rays will reduce the likelihood of eye damage, as they filter out both types of harmful rays. For the best level of protection, select sunglasses that block UV-A and UV-B rays between 290 and 400 nanometres or that block at least 98 percent of both types of UV rays. It is important to note, however, that labeling standards for sunglasses are voluntary and not mandatory.