It is commonly known that UV rays from the sun can severely damage the eye. The main source of UV rays is the sun. They are normally located over the violent part of light spectrum that is visible to the eye. UV is classified into three major classes. That includes UVA, UVB, and UVC. UVA is easily able to pass through normal glass. Before are facts regarding sunglasses lens types.
Whether this form of UV is injurious to the eye or not is a matter of contention among scientists. However, the second class of UV rays is the most dangerous to the eyes. UVB causes the most damage to the eyes and are the reason it is important to wear sunscreen and sunglasses because they cannot pass through. UVC rays do not reach the earth because they are blocked by the atmosphere.
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.
Another lens design is the polarized lens. This is usually designed such that it reduces the glare coming from glass, snow and water surfaces. They make images to appear sharper and clearer. They are available in both non-prescription and prescription glasses and those who are sensitive to light can wear them indoors. These glasses are usually a good choice for patients who have undergone a post-cataract surgery.
Active individuals should go for polycarbonate lenses. This is because these lenses are impact-resistant and resilient. Most parents buy their children these lenses because kids always damage sunglasses.
Whether this form of UV is injurious to the eye or not is a matter of contention among scientists. However, the second class of UV rays is the most dangerous to the eyes. UVB causes the most damage to the eyes and are the reason it is important to wear sunscreen and sunglasses because they cannot pass through. UVC rays do not reach the earth because they are blocked by the atmosphere.
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.
Another lens design is the polarized lens. This is usually designed such that it reduces the glare coming from glass, snow and water surfaces. They make images to appear sharper and clearer. They are available in both non-prescription and prescription glasses and those who are sensitive to light can wear them indoors. These glasses are usually a good choice for patients who have undergone a post-cataract surgery.
Active individuals should go for polycarbonate lenses. This is because these lenses are impact-resistant and resilient. Most parents buy their children these lenses because kids always damage sunglasses.
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