A blonde, a brunette and a redhead were stuck on an island for many, many years until one day they found a magic lamp. They rubbed it hard and out popped a genie. He said that he could only give three wishes so since there were three girls, each would get one wish. The redhead went first. ''I hate it here. It is too hot and boring. I want to go home!'' ''Okay,'' replied the genie. And off she went. Then the brunette went. ''I miss my family, my friends and relatives. I want to go home, too!!'' And off she went. The blonde started crying and said, ''I wish my friends were back here!''
One of the most important reasons to wear a sunglass
is to protect your eyes from harmful ultraviolet rays.
Recent studies indicate that greater amounts of the sun's ultraviolet (UV) radiation are reaching the earth's surface.
UV is divided into three ranges - A, B and C:
-- Prolonged exposure to UVA and UVB can cause significant eye damage, everything from temporary discomfort to long-term vision problems such as cataracts.
-- UVC is not considered a threat because most of it is filtered by the earth's protective ozone layer (although pollutants are degrading the ozone, thus increasing UV exposure).
Make sure your sunglasses have 100% UVA and UVB protection.
UV radiation is most intense between 10 a.m. and 3 p.m., will be stronger at higher altitudes and closer to the equator.
Snow, sand and water intensify the effects of UV radiation, harming unprotected eyes, even over a brief time period.
An overcast day will block solar brightness while still allowing 80% UV light to reach your eyes and skin.
Babies and young children are more susceptible to UV damage because they have more translucent corneas and lenses.
Polarized lenses are great for reducing glare, however, polarization alone does not block UV rays.
Sunglass Lens Options
The first thing to check for is an optically correct lenses. A cheaply made lens with have imperfections that will slightly distort an object. If the edge is distorted or curves as you move the glasses then you will have to continually refocus and this causes severe eye strain leading to headaches, nausea and dizziness.
Lens Materials:
If vision quality is the priority then choose glass lenses. Choose a plastic lens if safety or impact-resistance is required.
Glass Quality glass lenses offer the best viewing quality and the most scratch-resistant. They will be heavier, cost more money and are more prone to shatter when hit.
CR-39 Plastic is thinner and weighs half as much as glass It exceeds the FDA requirements for impact-resistance.
Polycarbonate Plastic A remarkable strong plastic, it weighs the least and is the most impact-resistant making it a perfect choice for rugged sunglasses. They also offer built-in ultraviolet. These are a good choice for kids sunglasses, sports & outdoor activities, and safety glasses
Acrylic Plastic Will weigh less and are the least expensive. They are soft and will scratch very easily. Must be specially treated to block UV.
Lens Tints or Colors:
The darker the tint, the more light it absorbs.
Amber, Orange or Copper Reduces blue light (a chief component of glare), increases contrast, brightens and enhances detail. Ideal for "high glare" sports such as boating, fishing and skiing, and flying.
Brown Cuts glare, works well in variable light conditions and allows excellent contrast. It's dark color minimizes eye strain making it good for driving, flying, cycling or running.
Gray Neutral shade that keeps color distortion to a minimum and will let you see most naturally while also reducing glare. Especially good for golf, running or cycling.
Green Enhances contrast in low light conditions and will reduce eyestrain in bright light conditions for greatest visual detail. Best general all purpose lens.
Rose Offers high contrast and is very soothing to the eyes while providing excellent light and glare protection. Works well in all daytime light conditions.
Vermilion Used to contrast objects against blue and green, they provide excellent perception in the low light conditions of an overcast day while offering acceptable protection in bright sunlight. Good color for driving or cycling.
Yellow Provides depth perception and visual contrast in low light conditions. Ideal for night riding, overcast, haze or fog conditions. Favorite of the ski industry.
Coatings:
The darker the original tint, the more light it absorbs.
Anti-reflective Consist of several layers of metal oxides applied to the front and back lens surface. Because of the layering effect, AR coatings sometimes have a hint of green or purple color, depending on the individual manufacturers process. Each layer is calculated to block reflected light resulting in a reduction in glare, annoying reflections and halos around light sources. AR coatings are most useful on water and snow.
Gradient Permanently shaded from top to bottom. A double-gradient lens is dark at the top & bottom and lighter in the middle. Most often found in driving and flying lenses so that the dashboard and instrument panels are seen clearly.
Mirror or Flash Highly reflective and greatly reduces the amount of light that reaches your eyes. Generally applied over a dark sunglasses lens, but can be applied over any base color. Mirror coated lenses absorb anywhere from 10% to 60% more light than uncoated lenses. These are good for higher altitudes, sand, water and snow. Although the most common are the silver, gold and copper metallic coatings, you will find many colors available nowadays.
Photochromic Will automatically darken and lighten when the light changes, although the cheaper photochromic lenses won't get very dark and take some time to adjust to different conditions. Will require conditioning the lens first through several exposures to the sun in order to darken fully.
Polarized A filter sandwiched between the front and back surface of the lens which filters out horizontally reflected glare and allows you to see through glare on the surface of water, snow, ice, glass etc. Ideal for water sports or winter sports where the water and snow increase the reflected glare. Absorbs 98% of the reflected glare.
Scratch-Resistant No lens material is scratch-proof, although a lens that is treated front and back with a clear, hard coating does become more resistant to scratches. Most types of plastic lenses have built-in scratch-resistant coatings.
Ultraviolet Treatment Blocks the sun's harmful UV rays from damaging your eyes. Overexposure to ultraviolet light is thought to be a cause of cataracts, retinal damage and other eye problems.
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