LENS TECHNOLOGY & TYPES
HELPFUL INFORMATION FOR YOUR EYES
The Edge would like to help you understand what is involved in the purchase of modern eyewear. Here is a list of terms, definitions, and Sport-Specific Guidelines that will guide you through the process of finding your perfect frame!!
Impact resistant blended lens material. Polycarbonate is lighter and thinner than standard plastic and glass lenses, it is impact resistant and won’t shatter, however it can create less than optimal color visualization compared to glass and plastic, although most people do not notice this difference. This lens is recommended for kids’ glasses, sport glasses, and occupational hazard glasses.
Polarized lenses are oriented to block the horizontally vibrating component of light, which reduces reflected light. This helps decrease driving fatigue from road reflections, allows visualization of objects under the water surface (great for fishermen), comfort at the beach, or a more enjoyable day on the ski slopes by reducing glare caused by reflections from the snow. The Edge Optics experts can show you some tricks in determining if a lens is actually polarized or not! One thing you may notice is that you will see a rainbow effect on the windows of your car when driving because of the way polarized lenses transmits light. You will get used to it!
CR39 plastic lenses
This is the industry-standard everyday lens. It is lighter than glass lenses and not as likely to shatter or chip, but still provides similar visual performance. CR-39 transmits 92% of visible light (8% is lost through surface reflections), and has inherent UV inhibitors that block UV light below 350nm.
A Photo-chromic lens lightens its tint when there are lower light levels, and darkens the tint when the light intensity increases. Traditionally, these lenses are activated by UV light which is great for transitioning from indoors to outdoors. Because of UV blocking properties, present in today’s auto windshields, these lenses did not darken enough when driving. This was a complaint often heard from the consumer. However, new photo-chromic lenses are available that are polarized AND darken according to visible light waves which allows them to change behind the auto windshield. This is the wave of the future—get it (light waves…)?!
A new lens that is more impact resistant and lightweight than polycarbonate lenses! They are usually an aspheric design which provides better optics with less distortion. The lenses are thinner than plastic or glass lenses. The Trivex/NXT is recommended for kids, sport frames, and occupational hazards. Very good quality and durability!
Ultraviolet light is a part of the light spectrum received by the sun.
Ultraviolet light is divided into 3 categories based on their wavelength:
- UVA is between 400=320nm
- UVB 320-290nm
- UVC 290-200nm
UVC is filtered by the earth’s atmosphere; however mountaineers should still be concerned about possible exposure because UV light increases in intensity at high altitudes. This could also apply to really any active Colorado resident.
Sand reflects 20-30% of UV light, snow reflects 85-95% of UV light, compared to grass and water at least than 10%. This is why it’s crucial to wear UVA/UVB protected eye wear even in the winter! You can literally sunburn your eyes. This is very painful and NOT recommended! UV light is a major cause of cataracts and macular degeneration in the eye, as well as cancers and other skin diseases in and around the eye. People who live in an area where the average amount of sunlight exposure is 12 hours have four times the amount of cataract formation compared to those who have 7 hours of exposure. Don’t forget this also applies to your KIDS!!! They have even more sensitive eyes and need that protection. It is so sad to see parents with sunglasses pushing their child in a stroller that is just blinded by the sun. Think about it! This should be identified as a real health hazard. YOU need to be on the cutting edge!
A/R or non-glare coatings
These coatings help reduce glare from surface reflections on your lenses. A coating placed on the front side of your lenses reduces the glare appearance of your lenses to other people as well. You will want this technology so that people can see your eyes. A/R coating also increases the light transmission to your eyes for low light conditions (at night) so you will see more than someone who does not have A/R coating on their lenses. An A/R coating on the back surface of your lenses cuts reflections you see in your lenses from light sources behind and to the side of you.
Brown and Grey tints are the most chromatic neutral tints, meaning they will not distort the actual color of objects. Brown lenses like yellow tints have a higher absorption of shorter visible wavelengths(blue light), which is responsible for most light scatter, thereby increasing contrast sensitivity on a hazy, smoggy, snowy, or overcast day.