It is a well-known fact that UV rays from the sun cause a lot of defects to the eye. These rays are found above the violent section of visible light spectrum and the major source is the sun. They exist in three major forms, which include UVC, UVB, and UVA. The wavelength in UVA is long and that permits it to penetrate glass with ease. Here is information about sunglasses lens types.
Scientists have not proved whether UVA can damage the eye or not. On the other hand, the second type of UV rays is extremely dangerous to the eye. This type is the UVB. It is advisable for people to wear sunglasses since these rays are not able to pass through glass. The UVC rays are blocked by the atmosphere and for this reason, they are not able to reach the earth.
As such, it is important to wear sunglasses as a preventive measure against damage that UVB causes. Besides serving as a preventive measure, sunglasses also act as a corrective measure for various eye defects. For instance, people who have myopia or long-sightedness need glasses to be able to see better at close and long range respectively. In order for these glasses to work effectively, they need to have lenses.
There is a wide range of lenses, which are used to achieve different effects when worn. Some examples of sunglass lens types include aspheric, bifocal and trifocal, Hi-Index, photochromic, polarized, polycarbonate, and progressive. Aspheric lenses are made with a complex front surface that changes in curvature gradually from the center towards the edge. They are designed to correct small distortions in vision. They are convenient to wear and carry because they are lighter and thinner.
On the other hand, bifocal lenses are usually made for correcting both short-sightedness and far-sightedness. Far-sightedness is corrected by use of the lens on the upper part of the glasses while the glasses on the lower part are meant for correcting short-sightedness. Old people are usually prescribed these lenses since their near vision is weakened due to aging. Trifocal lenses usually incorporate into a bifocal lens the ability of a person to see objects that are a few feet away.
Photochromic lenses are made in a manner that they become dark when they come in contact with sunlight. This adaptation makes them suitable for individuals who would otherwise need to carry multiple sunglasses for different situations. They are available in all lens designs and materials. That means that one can find bifocals, trifocals, and hi-index lenses that are also photochromic.
Polarized lenses are designed to reduce the glare that comes from surfaces such as water surfaces, glass, and snow. This makes images to appear clearer and sharper. One can get them in both prescription and non-prescription sunglasses. They can be worn indoors by people who are sensitive to light. Post-cataract surgery patients make very good candidates for glasses with polarized lenses.
Another very common type of lens is the polycarbonate variety. This variety is suitable for people who maintain active lifestyles. For instance, the playful nature of children makes these products very suitable for them. Many parents buy their kids sunglasses with polycarbonate lenses because they are impact-resistant and resilient.
Scientists have not proved whether UVA can damage the eye or not. On the other hand, the second type of UV rays is extremely dangerous to the eye. This type is the UVB. It is advisable for people to wear sunglasses since these rays are not able to pass through glass. The UVC rays are blocked by the atmosphere and for this reason, they are not able to reach the earth.
As such, it is important to wear sunglasses as a preventive measure against damage that UVB causes. Besides serving as a preventive measure, sunglasses also act as a corrective measure for various eye defects. For instance, people who have myopia or long-sightedness need glasses to be able to see better at close and long range respectively. In order for these glasses to work effectively, they need to have lenses.
There is a wide range of lenses, which are used to achieve different effects when worn. Some examples of sunglass lens types include aspheric, bifocal and trifocal, Hi-Index, photochromic, polarized, polycarbonate, and progressive. Aspheric lenses are made with a complex front surface that changes in curvature gradually from the center towards the edge. They are designed to correct small distortions in vision. They are convenient to wear and carry because they are lighter and thinner.
On the other hand, bifocal lenses are usually made for correcting both short-sightedness and far-sightedness. Far-sightedness is corrected by use of the lens on the upper part of the glasses while the glasses on the lower part are meant for correcting short-sightedness. Old people are usually prescribed these lenses since their near vision is weakened due to aging. Trifocal lenses usually incorporate into a bifocal lens the ability of a person to see objects that are a few feet away.
Photochromic lenses are made in a manner that they become dark when they come in contact with sunlight. This adaptation makes them suitable for individuals who would otherwise need to carry multiple sunglasses for different situations. They are available in all lens designs and materials. That means that one can find bifocals, trifocals, and hi-index lenses that are also photochromic.
Polarized lenses are designed to reduce the glare that comes from surfaces such as water surfaces, glass, and snow. This makes images to appear clearer and sharper. One can get them in both prescription and non-prescription sunglasses. They can be worn indoors by people who are sensitive to light. Post-cataract surgery patients make very good candidates for glasses with polarized lenses.
Another very common type of lens is the polycarbonate variety. This variety is suitable for people who maintain active lifestyles. For instance, the playful nature of children makes these products very suitable for them. Many parents buy their kids sunglasses with polycarbonate lenses because they are impact-resistant and resilient.
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