Which is better CR-39 or polycarbonate?

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.

Is CR-39 clearer than polycarbonate?

CR-39 Lenses: Pros & Cons CR-39 is the most basic lens material available. 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.

Do CR-39 lenses scratch easily?

It is also not easily scratched. Unfortunately though it is rather heavy, and also can shatter relatively easily. And most of all, it gets thick quickly, as you increase the diopter values. Because of weight and shatter risk, glass is rarely used in prescription lenses these days.

Is CR-39 a glass?

CR-39 is about half the weight of glass with an index of refraction only slightly lower than that of crown glass, and its high Abbe number yields low chromatic aberration, altogether making it an advantageous material for eyeglasses and sunglasses.

What does CR 39 stand for?

Columbia Resin 39
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.

Does CR 39 have UV protection?

Results: All the tested lenses absorbed all of the UV-B and at least 99% of UV-A. 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.

What does CR-39 stand for?

Does CR-39 have UV protection?

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.

How thick are CR-39 lenses?

It is resistant to scratches, most solvents, and material fatigue. For safety glasses, CR-39 is rated only for low-impact applications and must be ground to a 3 mm center thickness. Lenses for nearsightedness are thicker on the edges, so using CR-39 produces a lens with a thick edge.

Does CR 39 block UV?

Which is the best lens for eyes?

Top Selling Eye Lenses Brands

• Johnson and Johnson Contact Lenses.
• Ciba Vision Contact Lenses.
• Bausch & Lomb Contact Lenses.
• Cooper Vision Contact Lenses.
• Aryan Contact Lenses.
• Acme Yearly Toric Contact Lenses.
• Celebrations Contact Lenses.
• Silk Lens Contact Lenses.

Is the CR-39 lens an impact resistant lens?

A CR-39 lens is quite impact resistant. If you live a regular lifestyle, or wear your glasses just for the regular lifestyle aspects, being concerned about a shattering lens might be overblown. In all my years I never even heard of a case where a plastic lens caused any injuries.

Which is better for rimless glasses polycarbonate or CR-39?

CR-39 Cracks Easily, When Drilled. This only matters if you choose rimless glasses, where the mounting point of the lenses has to be drilled into the side of the lens. Polycarbonate takes well to this treatment, where CR-39 does not. So if you want a rimless design, you need to go with polycarbonate.

Do you have to drill holes in CR-39 lenses?

In other words, drilling holes into this type of lens, as you would need for a frameless design, tends not to work out so well. CR-39 lenses like to crack along drill holes, so optic shops tend not to accept these lenses unless you get a full frame.

How are eyeglass lens prescriptions written for myopia?

Eyeglass lenses prescribed for myopia (nearsightedness) are concave, meaning they’re thicker on the edges than in the middle. This causes light rays passing through it to diverge. This prescription for myopia is written down as a negative or “minus” number, such as -3.00 diopters.