Protecting your eyes from the sun's harmful rays is very important if you are spending any time outdoors. Even days that are hazy or dull require protection for our eyes. Here are a few considerations.
Sunglasses come in a bewildering array of choices; never have there been so many options to select from. With all the variety you'll want to know ahead of time what the differences are between tinted, reflective, photochromic and polarizing lenses. Of course the style of frame and size of lenses will be obvious differences when shopping for sunglasses. It will also be important to know exactly what purpose you'll be using your sunglasses.
Sunglasses allow for us to see easier in the bright light. Some glasses protect against ultraviolet (UV) rays while reducing glare and giving protection from physical damage that may be caused to the eyes. Everyone is at risk for sun related eye problems. People who spend long hours in the sun during work or outdoor activity are at higher risk, than someone who is working indoors all day long. Other people may be at higher risk of eye damage if they are on certain medications such as; tetracycline, birth control pills, diuretics and sulfa drugs.
Ultraviolet light can damage both the cornea and retina, so with a good pair of sunglasses the UV can be eliminated from entering the eye completely. Whatever sunglasses you select they should provide the most possible UV protection possible. It's good to find a pair of glasses that block the sun from all angles, best achieved with a large framed pair that wrap around the face. Purchase sunglasses that block both the UVA and UVB rays, your lenses should indicate this when buying them, if they don't specify what protection is offered it is best not to buy them. On top of wearing sunglasses it is a good idea to wear a wide brimmed hat.
Manufacturers use different colors of tints to produce specific results for a variety of sunglasses needs. The color of the tint will determine the parts of the light spectrum that will be completely absorbed by the sunglasses. Yellow or gold tints reduce there opposite color, which is blue while allowing other lights to pass through. Blue lights tend to create a glare otherwise known as blue haze. Gray tints are generally used as an all- purpose tints reducing the overall brightness with the least amount of color distortion. The gray lenses are a good lens for general use and driving. Brownish and amber tints are another example of good all-purpose glasses. They reduce glare, absorbing blue and UV rays. Blue and violet have been shown to contribute to cataract formation. Purple and rose tints are great choices for water sports or golfing as they offer contrast of objects against a blue or green background. Green tints are another popular option as they absorb some blue light while reducing glare.
Survey conducted on Prescription Eyeglasses
By Timothy Gorman Prescription eyeglasses and/or contact lenses are worn by over 60% of the nations population today. The end of the year 2006, it is estimated that 176 million people will be in nee..
By Timothy Gorman Prescription eyeglasses and/or contact lenses are worn by over 60% of the nations population today. The end of the year 2006, it is estimated that 176 million people will be in nee..
To recognize a pair of reflective sunglasses they will be the pair with the mirrored look. Reflective sunglasses use a reflective coating called a half-silvered surface as it is applied in a very sparse, thin layer. The reason the process is called half-silvered is because the reflective molecules applied over the glass is distributed evenly but only half the glass is covered because of the speckled process. Thus the surface will reflect only about half the light striking the surface, letting the other half go through the glasses. Many styles of mirrored glasses come in gradient forms that have additional protection on the top part of the glasses with less protection at the bottom of the lenses. Mirrored sunglasses are unfortunately easily scratched so extra caution must be used to keep them protected.
Both sunglasses and prescription eyeglasses that darken when exposed to the sun are known as photochromic (or photochromatic) sunglasses. The special lenses work by using a chemical reaction with the UV radiation. The lenses have millions of molecules of substances such as silver halide or silver chloride. When the lenses are exposed to UV rays from the sunlight, the molecules embedded in the lenses undergo a chemical reaction causing them to absorb light thus darkening.
Without the UV light, the lenses go back to their original state, it should be noted that the lenses would not darken in the car as the windshield block out most of the ultraviolet light. Most of the photochromic lenses do however have a bit of tint included in them, so they will still work while driving.
It helps to know a bit about polarization to understand why polarized sunglasses work. Polarization happens when radiation, especially light through being transmitted, scattered, refracted or reflected is restricted to vibrate in only one particular direction, it can occur both naturally and artificially. An example of natural polarization is when you look at the ocean or a lake, the glare off the surface is a result of the light that did not make it through the filter of water, therefore you cannot see below the surface. What polarized lenses does is allows the vertically polarized light to enter from most horizontal surfaces such as highways and water. A good test to see whether sunglasses are polarized or not is to find a reflective surface and with the glasses in front of the surface you want to view, slowly rotate the glasses checking to see if the glare diminishes, if it does the glasses are polarized. Photographers often use special polarized lenses atop their ordinary lenses to avoid unnecessary glare from surfaces.
There are a few extra features of sunglasses that will add to the quality of your lenses. Scratch-resistant coating is achieved by applying a thin durable film on the surface of the lenses; this extends the life and safety of your glasses, as it's almost impossible to wear a pair of glasses with a scratch on them while trying to see properly. Anti-reflective coating reduces what is known as back-glare, a result of light hitting the back of the sunglasses and bouncing into the eyes. Lastly the most popular coating is the ultraviolet or UV coating. Some of the most serious of eye problems can be linked to UV light, both UVA and UVB. A good UV coating on your sunglasses will eliminate UV radiation, it is important to check that your glasses filter out one hundred percent of both UVA and UVB, there should be a label on your sunglasses stating this information.
The optics of Prescription Eyeglasses
By Timothy Gorman There are estimated 168 million people who wear prescription eyeglasses in the United States. Only a very small percentage of those people could tell you what strength their lenses..
By Timothy Gorman There are estimated 168 million people who wear prescription eyeglasses in the United States. Only a very small percentage of those people could tell you what strength their lenses..
Sunglasses come in a myriad of design, color choices and styles. Popular designers offer glasses in prescription, men's, women's, sports and junior varieties. A suggestion when purchasing sunglasses is to try and select a pair that blocks the light from all angles, preferably one that wraps all the way around the face, this is if you want the ultimate eye protection. Of course with all the choices available you'll most importantly select sunglasses that block both the UVA and UVB radiation in a style that provides comfort and the right fit.
Whatever sunglasses you decide on wearing you will feel safer knowing you are eliminating harmful rays from entering your eyes. By properly taking care of you're eyes you can hopefully avoid problems such as cataracts, cancer of the eye or photokeratitis (sunburn of the retina) and macular degeneration, (which is the leading cause of blindness in people over 65). Paying a little extra for a pair of sunglasses with one hundred percent protection is a smart investment.
About the Author:
Valerie Giles owns and operates Best Sunglasses Online, a sunglasses site showcasing an extensive selection of discount sunglasses [ http://www.best-sunglasses-online.com], designer sunglasses, aviator sunglasses and prescription sunglasses [ http://www.best-sunglasses-online.com/prescription-sunglasses.htm]. Find all the top name brands. [ http://www.best-sunglasses-online.com]
