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.
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 are certain varieties of lenses that are worn in order to realize diverse effects. Such examples of lenses include polycarbonate, progressive, polarized, photochromic, bifocal and trifocal, aspheric and Hi index. Aspheric lenses are created using a complex front surface that curves progressively from the middle to the edge. They are used for correcting minor defects in vision. Their lightness and thinness makes them convenient to carry and wear
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 designed in a way that they darken when they are hit by sunlight. This feature is very convenient for most people that would otherwise have to carry multiple sunglasses for different conditions. These lenses are available in all materials and lens materials. For instance, it is possible to find high-index, bifocal, and trifocal lenses that are photochromic. They are a popular choice for people of all ages.
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.
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 are certain varieties of lenses that are worn in order to realize diverse effects. Such examples of lenses include polycarbonate, progressive, polarized, photochromic, bifocal and trifocal, aspheric and Hi index. Aspheric lenses are created using a complex front surface that curves progressively from the middle to the edge. They are used for correcting minor defects in vision. Their lightness and thinness makes them convenient to carry and wear
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 designed in a way that they darken when they are hit by sunlight. This feature is very convenient for most people that would otherwise have to carry multiple sunglasses for different conditions. These lenses are available in all materials and lens materials. For instance, it is possible to find high-index, bifocal, and trifocal lenses that are photochromic. They are a popular choice for people of all ages.
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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