The Current Picture
At present the market of sunshades is experiencing an incredible rise. With various celebrities and designers plunging in, the sunglasses business has further picked up pace. But this has indirectly turned out to be a little troublesome for common people like us who wish to have a pair of branded sunshades that serves our purpose of protecting our eyes at the same time makes us appear trendy and is not heavy on pocket. So selecting the right pair of sunglasses has become a Herculean task today.
Facts you must know about Sunglasses
The Darkness of the Lens and UV Rays
There is no liaison between the ultraviolet rays that are known for their piercing nature and the extent of darkness or tint of the lens of your sunglasses. Even clear lenses can cent percent absorb the ultraviolet rays. So if you seek protection from the damaging UV rays, check the degree to which the sunglass lens ‘blocks' or ‘absorbs' them. Generally the lenses are 70 to 90 percent absorbent of the sunrays. The cosmetic sunglasses block only 60 percent of light that falls on the lens.
Remember that low quality sunshades can dilate the pupil and cause extra exposure of ultraviolet rays on the lens, thereby harming your eye. So it is better to buy sunshades of a good company. You can also take your sunglasses to any optical shop or eye practitioner and get their UV rays absorption limit tested in order to ensure perfect safety to your eyes.
What are Polarized Lenses
Polarized lenses are made up of Polaroid or a similar material. Polarized lenses minimize the glare due to light reflected from polarizing surfaces such as water and also from the polarized diffuse sky radiation. It basically permits light coming from the vertical meridian and discards light from the horizontal meridian. Sunglasses with polarized lenses are ideal for the people much into swimming and other water sports and in activities such as driving.
Anti reflective lenses versus Polarized Lenses
Anti-reflective lenses as the name suggests cuts out most of the reflections that are produced by the light that rebounds between the two lens surfaces and obstructs in a proper vision. In contrast to this the polarized lenses rejects light completely from the horizontal meridian and reduces the glare.
There are different types of materials used to make sunglass lenses. For instance CR-39 is a plastic made from hard resin that offers perfect optical quality standards. Similarly Glass is a material that is heavy but more resistant to scratches. Some lenses are made of polycarbonate, a synthetic plastic material that has quite strong but lightweight. However in comparison to other lenses these lenses are light and more impact-resistant.
Quality of the lens
Lens is the main component of the sunglass. So its quality is of extreme significance. In order to adjudicate the quality of a lens, follow some simple steps. Find a tiled floor or any surface that has repeating lines. Hold your pair of sunglasses close to the floor but away from your face. By closing one of your eyes, and slowly moving the sunglass in all directions, try to look at the lines through one of the lenses. If the lines appear straight to you, as they actually are, your sunshade is supplied with good lenses but if the lines on the floor seem to be wavy or distorted lenses are of a poor quality.
Coatings on lenses
Coatings on the lenses of sunglasses are mainly types such as mirrored coating, anti-reflective, waterproof and scratchproof coating. These coatings serve different purposes as per their names and augment the quality as well as the price of the lens. Besides coatings many high-tech and advanced sunglasses are worked upon with technology to increase clarity, better protection, good contrast and block specific kind of light.
Regular and Photochromic
A regular lens functions in normal way by reducing the brightness of everything evenly. But a photochromic lens adjusts with the intensity of ultraviolet radiation falling on it. It turns dark when outdoors and become light when indoor. Sunglasses with photochromic lenses should be worn particularly by people with weak and sensitive eyes and by those who drive a lot.
Sunglasses and Frames
Usually in sunglasses like in normal spectacles, frames refine the light that comes via the lenses and do not protect against ambient light, direct light and glare from different directions. To ward off this extra light ‘wrap around frames' and other sidereal attachment are used. Frames too are made of different materials. Just like the quality of the lens, the quality of the material of which the frame is made is directly proportional to the cost of the sunshade. Top brands such as Maui Jim, Revo, Serengeti etc. use frames that are high in strength but light in weight.
Some general points
Your sunglasses might be 100% absorbent of the ultraviolet rays, still some light can reach your eyes from the sides of the glasses.
Even if you are wearing contact lenses, while moving out in the sun, sunglasses are must.
Sunglasses eliminate specific frequencies of light.