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.
It is an issue of dispute among scientists whether UVA rays are harmful to the eyes. On the contrary, UVB pose a very big danger to eyes because they are capable of causing harm. It is vital put on sunglasses and sunscreen because of the harm UVB causes. UVB rays cannot pass through glass or sunscreen. Lastly, UVC are not available on the surface of the earth because they are blocked by the atmosphere.
Since UVB rays can damage the eye, it is always necessary to wear sunglasses as a protective measure. Other than acting as a protective gear for UVB rays, sunglasses also help prevent a number of defects of the eye. For example, people who have eye conditions such as long-sightedness or myopia require glasses to see well at long and close range respectively. Lenses are necessary in order for these glasses to work well.
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.
It is an issue of dispute among scientists whether UVA rays are harmful to the eyes. On the contrary, UVB pose a very big danger to eyes because they are capable of causing harm. It is vital put on sunglasses and sunscreen because of the harm UVB causes. UVB rays cannot pass through glass or sunscreen. Lastly, UVC are not available on the surface of the earth because they are blocked by the atmosphere.
Since UVB rays can damage the eye, it is always necessary to wear sunglasses as a protective measure. Other than acting as a protective gear for UVB rays, sunglasses also help prevent a number of defects of the eye. For example, people who have eye conditions such as long-sightedness or myopia require glasses to see well at long and close range respectively. Lenses are necessary in order for these glasses to work well.
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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