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.
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.
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 different types of lenses which give different effect when a person wears them. These types of sunglass lens include progressive, polycarbonate, polarized, photochromic, Hi-index, trifocal and bifocal. A complex front surface is used to make aspheric lenses. This surface gradually changes its curvature from the center towards the edge. These lenses are meant for correcting minor vision distortions. Due to their light weight and thinness, they are suitable for carrying and wearing.
Bifocal lenses are made in a special way to be able to correct far-sightedness as well as short-sightedness. The lens in the upper part of the glasses is for correcting far-sightedness while the lower part has a lens for correcting short-sightedness. They are mostly prescribed for old people whose near-vision has deteriorated as a result of aging. Trifocal lenses add the ability to see objects that are a few feet away into bifocal glasses.
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.
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.
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.
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 different types of lenses which give different effect when a person wears them. These types of sunglass lens include progressive, polycarbonate, polarized, photochromic, Hi-index, trifocal and bifocal. A complex front surface is used to make aspheric lenses. This surface gradually changes its curvature from the center towards the edge. These lenses are meant for correcting minor vision distortions. Due to their light weight and thinness, they are suitable for carrying and wearing.
Bifocal lenses are made in a special way to be able to correct far-sightedness as well as short-sightedness. The lens in the upper part of the glasses is for correcting far-sightedness while the lower part has a lens for correcting short-sightedness. They are mostly prescribed for old people whose near-vision has deteriorated as a result of aging. Trifocal lenses add the ability to see objects that are a few feet away into bifocal glasses.
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.
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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