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.
The correction of far-sightedness as well as short-sightedness is done by bifocal lenses. The lens located in the lower part is meant for correcting short-sightedness while that in the upper part of the glass are for improving long-sightedness. Their prescription is mostly for the elderly people because vision develops defects as one ages. Trifocal lenses incorporate into bifocal lenses the ability to see objects that are located only a couple of feet away.
When light from the sun hits photochromic lenses, they become darker. This makes them convenient for people who require multiple sunglasses for various conditions. These lenses can be found in all lens materials. For example, one can find trifocal, bifocal or high-index lenses that are photochromic. Most people regardless of the age prefer photochromic lenses.
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.
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.
The correction of far-sightedness as well as short-sightedness is done by bifocal lenses. The lens located in the lower part is meant for correcting short-sightedness while that in the upper part of the glass are for improving long-sightedness. Their prescription is mostly for the elderly people because vision develops defects as one ages. Trifocal lenses incorporate into bifocal lenses the ability to see objects that are located only a couple of feet away.
When light from the sun hits photochromic lenses, they become darker. This makes them convenient for people who require multiple sunglasses for various conditions. These lenses can be found in all lens materials. For example, one can find trifocal, bifocal or high-index lenses that are photochromic. Most people regardless of the age prefer photochromic lenses.
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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