It is common knowledge by now that UV rays from the sun cause a lot of damage to the eye. UV rays are located above the violet portion of the visible light spectrum and its main source is sunlight. There are three main categories of UV, that is, UVA, UVB, and UVC. UVA has a longer wavelength, which allows it to pass through normal glass easily. The information below is worth knowing 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.
In order to prevent the harm caused by UVB, it is necessary to put on sunglasses. Apart from sunglasses being used as a protective mechanism against light, they can also be used to correct various eye defects. An example is where people who are short- or long-sighted wear glasses to correct defect in their vision. These glasses require lenses for them to work properly.
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.
Polycarbonate lenses on the other hand are a good option for individuals who are always active. These lenses are made such that they are able to withstand impact and are very durable. They are commonly bought by most parents for their kids since kids commonly damage sunglasses.
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.
In order to prevent the harm caused by UVB, it is necessary to put on sunglasses. Apart from sunglasses being used as a protective mechanism against light, they can also be used to correct various eye defects. An example is where people who are short- or long-sighted wear glasses to correct defect in their vision. These glasses require lenses for them to work properly.
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.
Polycarbonate lenses on the other hand are a good option for individuals who are always active. These lenses are made such that they are able to withstand impact and are very durable. They are commonly bought by most parents for their kids since kids commonly damage sunglasses.
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