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.
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.
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.
Another very common type of lens is the polycarbonate variety. This variety is suitable for people who maintain active lifestyles. For instance, the playful nature of children makes these products very suitable for them. Many parents buy their kids sunglasses with polycarbonate lenses because they are impact-resistant and resilient.
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.
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.
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.
Another very common type of lens is the polycarbonate variety. This variety is suitable for people who maintain active lifestyles. For instance, the playful nature of children makes these products very suitable for them. Many parents buy their kids sunglasses with polycarbonate lenses because they are impact-resistant and resilient.
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