Sunglasses : What is it?
Sunglasses protect the eyes from ultraviolet (UV) rays, which can cause eye damage and vision problems. They also reduce glare from the sun and block out intense light to improve one's vision, especially in outdoor environments. Some are also designed to eliminate certain light frequencies to reduce blurring or enhance contrast.
Sunglasses designed for everyday use usually have glass lenses, which block UVB rays – the type of UV that causes most sun-related eye problems. Sports sunglasses are usually made of a tougher polycarbonate lens to withstand impact and shattering. Most sunglass lenses are polarized, or designed to rearrange light rays to improve contrast and vision.
Kinds of Sunglasses include the following:
Gray-tinted sunglasses are used for general shading and eye protection. They reduce the overall amount of light without altering or distorting any colors. They are ideal for driving and everyday use.
Yellow and gold lenses
Also called blue-blockers, these sunglasses block out blue light, which can scatter and cause haze. They enhance all other colors except blue, which makes images appear sharper and brighter. They are commonly used for winter and snow sports. They tend to affect color perception, making them unsuitable for activities that rely on accurate color.
Amber and brown lenses
These lenses absorb high-frequency colors, such as blue, resulting in a softer, milder color.
They are also good general-purpose sunglasses, especially in harsh midday sunlight. They also distort colors, but can improve clarity and contrast as well.
Green-tinted sunglasses reduce glare and partially block blue light. They provide the highest contrast and clearest vision, making them popular for both sports and general use.
Purple and rose lenses
These lenses enhance contrast against blue and green backgrounds. They are commonly used in outdoor activities, such as skiing and hunting.
|UV protection: Choose sunglasses that block at least 99% of UVA and UVB rays. UVA rays are less damaging to the eyes, but can damage the delicate skin surrounding them. Dark lenses do not necessarily mean more protection. Look for those labeled “UV 400,” which indicates that the lenses completely absorb both types. |
Coverage: Choose sunglasses that completely cover your eyes and the surrounding area. If you spend a lot of time outdoors, consider getting wraparound sunglasses, which clings to the eye area and prevents sunlight from getting in through the sides. Large lenses and sidereal features also cover more of the eye area.
Lens material: Choose sunglasses with durable, shatterproof lenses, especially if you will use them for sports or outdoor activities. Polycarbonate lenses cost more than glass ones, but will last longer and will not break easily. Look for scratch-resistant and multi-coated lenses.
Backglare: Backglare is the light that reflects on the lenses and bounces into the eyes. Reduce backglare by choosing lenses with anti-reflective coating on the inside, which absorbs light rays and prevents them from bouncing back.