1. What are polarized lenses?
Light reflected off flat surfaces like water and long, flat stretches of highway—often referred to as glare—is bent or polarized horizontally and generally is the type of light interfering with vision. Polarized lenses allow only vertically polarized light (“good” or “helpful” light, if you will) to pass through them.
2. Why are most sporting sunglasses lenses polycarbonate and not glass?
It depends on the endeavor. If the plan is to wear the sunglasses in a sport with potential for a high degree of contact like taking a spill while cycling or playing tennis, it just makes sense to go with a material that won’t shatter and possibly cause injury. In addition, polycarbonate is a thermo plastic that can be molded into virtually any shape to accommodate the sport, from an ample fully curving wrap to petite and flat.
3. Is lens tint strictly a personal preference or are there colors better suited for one condition versus another?
Although personal preference does play a role in tint selection, some colors perform better in certain conditions: Gray transmits all the colors of the light spectrum and is ideal for sports both on the water and nearby, in medium to bright sun conditions, making it a great all-around choice. Brown also transmits a wide spectrum of colors for truer color perception and high contrast. Brown performs optimally in lower light, however, and makes a great driving sunglass. Copper absorbs a high degree of blue light, which boosts contrast, heightens visual acuity and is soothing to the eye, so it is also great for low-light applications. More specialized colors like yellow for the ultimate in contrast are also available. Yellow is often used in delicate sight applications like target shooting. And some tints are just for fun like rose-colored lenses.
4. What is visible light transmission (VLT)?
VLT is the amount of light that reaches the eye after passing through the lens and is measured as a percentage. All-purpose sunglasses, for example, typically range in VLT from 15-25%, while those designed for scaling a glacier, where the light is blindingly bright, range in VLT from 4-10%. Watersports sunglasses typically have a VLT somewhere in between, depending on the particular condition for which they’re designed.
5. What are photochromic lenses?
Today’s photochromic lenses contain organic carbon-based molecules that grow and shrink in relation to the amount of UV light they encounter. The result is lenses that constantly adjust their tint level in reaction to the changing light conditions, from virtually clear indoors to quite dark in bright sunny outdoor conditions. Decent photochromic lenses should be able to fully adjust from one extreme to the other within about 10 seconds
6. If the sun doesn’t really bother me, should I still wear sunglasses outdoors?
Yes. Whether bright sunlight bothers you or not, invisible UV rays can cause damage to your eyes. Just like getting a sunburn on a cloudy day, you can do damage to your eyes via UV rays whether or not the degree of intensity of visible light is bothersome.
7. Should children wear sunglasses?
Children are at particular risk for eye damage from UV rays because generally they’re in the sun more than adults and their eyes are more sensitive than the eyes of adults. In addition, UV damage is cumulative over a person’s lifetime, which means you should begin protecting your child’s eyes as soon as possible.
8. What’s the purpose of an anti-reflective lens coating?
Because most sunglass styles do not completely encapsulate the eye like a pair goggles, light typically will enter the eye from areas other than just through the lens. The better manufacturers coat the back of their lenses with an anti-reflection coating that dampens light coming in from overhead, for example, that would tend to bounce off the back side of the lens and into the eye without it.