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Is CR-39 better than polycarbonate?
In comparison to polycarbonate, CR-39 provides vastly superior optics, rating just one rung below the material with the highest ABBE value: crown glass. On the flip side, CR-39 is the thickest and heaviest lens material.
Is CR-39 the same as polycarbonate?
An alternative material to polycarbonate is CR39 (Columbia Resin 39), a plastic polymer commonly used in the manufacture of eyeglass lenses. Unlike polycarbonate, CR39 requires a UV coating to be added to protect eyes from the sun’s harmful rays.
Is CR-39 clearer than polycarbonate?
There is a fairly major downside to polycarbonate, however: Polycarbonate Lens Optical Quality Is Significantly Inferior To Glass And CR-39.
How thick are CR-39 lenses?
Center Thickness As you can see from the graphic, with a -3 prescription the CR-39 lens is thickest but they’re all fairly close. This is because impact-resistant lenses can go as thin as 1.5mm. Since CR-39 is not impact-resistant, the thinnest it can go is 2mm. Next is the -6.
Are polycarbonate lenses thinner than CR-39?
Polycarbonate lenses have a higher index of refraction (1.586) than CR-39 plastic (1.498) and are therefore thinner in an equal lens prescription. With a higher index (of refraction), light is bent more efficiently, therefore it requires less material to achieve the eyeglass prescription making the lenses much lighter.
What are CR-39 single vision lenses?
The Crystal Vision CR39 Plastic lens for single vision distance vision is a good choice for corrections up to +/-4.00, and it is available with a variety of options such as Transtions, Tint, Standard Anti-Reflective coating, and the top-quality Crizal Coating.
What is CR-39 bifocal lenses?
Crystal Vision CR39 Bi-Focal Lenses Crystal Vision plastic CR39 lenses for bifocal vision distance viewing means that the reading area has a half moon shape with a “flat top”, in the bottow area of the lens. The standard CR39, flat top 28 bifocal has a reading area that is 28mm wide at the top.
What index is CR-39?
1.498
The refractive index of a basic plastic lens (CR-39) is 1.498 meaning that light travels 1.498 times faster in a vacuum than it does through the plastic lens. The higher the index of refraction the thinner a lens can be to get the same refraction effect.
Is CR-39 UV resistant?
Conclusions: These data suggest that UV tinted CR-39 lenses provide protection against UV radiation that meets the ANSI Z80. 3-1996 Standard for non-prescription sunglasses and fashion eyewear.
Does CR-39 block blue light?
Advanced blue light filter technology Our top-of-the-range CR-39 lenses block up to 40% of blue light at 430nm and up to 100% at 350-400nm.
Do CR-39 lenses block UV?
What are anti blue light lenses?
Blue light glasses (sometimes called blue light blocking glasses) are glasses that contain lenses specifically designed to reduce the amount of blue light that reaches the eye. These lenses filter blue light rays to help prevent them from entering your eye and causing potential damage.
Do opticians recommend blue light glasses?
The American Academy of Ophthalmology says you don’t need them and has gone on record as not recommending any kind of special eyewear for computer users. The organization says blue light from digital devices does not lead to eye disease and doesn’t even cause eyestrain.
Can you wear blue light glasses while watching TV?
The short answer is yes. Blue light lenses do help with preventing blue light from digital screens from reaching your eyes, which can help prevent or alleviate some of the unpleasant symptoms you experience from prolonged exposure to digital screens.
What is diff in CR 39 lenses and polycarb?
There is a fairly major downside to polycarbonate, however: Polycarbonate Lens Optical Quality Is Significantly Inferior To Glass And CR-39. And the difference is significant. What you gain in impact resistance and higher index, you pay for in how the lens transfers light into your eye.
Which lens is better Trivex or polycarbonate?
– Thickness. Polycarbonate lenses are about 10% thinner than Trivex lenses. – Weight. Trivex lenses about 10 percent lighter than polycarbonate lenses. – Optics – central. Trivex lenses have less internal stress and may produce sharper central vision than polycarbonate lenses. – Optics – peripheral. – Impact resistance. – UV protection. – Availability. – Cost.
What are CR 39 lenses?
Prescription Strength. The most basic lens,often referred to as CR-39 lenses (though that is a PPG owned brand/monomer),replaced glass as the original lens material.
What is a CR 39 lens?
The CR-39 was created to be an alternative to the heavy glass lenses. It weighs about half of the amount of glass lenses. The first high-index plastic was polycarbonate. Polycarbonate was originally developed for fighter jet cockpits. It is very strong, very light, and resistant to scratches and breaking.