What type of material is used for the lenses?

[Naima Eyeglasses]

I was wondering what type of material is used for the lenses? Are they pure glass? Or are they plastic? Are they light weight?

[Luke Eyeglasses]

Hi-index lenses are made of a special plastic material that refracts light in a different way than regular plastic lenses. With hi-index lenses, vision can be corrected with less material, making the lens much thinner. Plastics are graded in numbers, such as 1.50 or 1.67. The higher the number, the thinner the lens. Because they are thinner, hi-index lenses are also lighter, making them more comfortable to wear.

Polycarbonate lenses are made of a type of plastic that is more impact-resistant than standard plastic lenses. Polycarbonate lenses are also much thinner and lighter in weight.



Polycarbonate Lenses:

Polycarbonate lenses are made of a type of plastic that is more impact-resistant than standard plastic lenses. Polycarbonate lenses are also much thinner and lighter in weight. They are considered a high index plastic. Polycarbonate lenses also have built-in ultraviolet protection. Because of these properties, it is the lens material of choice for children’s lenses, sport lenses and safety lenses. However, some people complain that polycarbonate lenses fail to give them the crispest, clearest vision.
Trivex Lenses:

Trivex is a relatively new material that is similar to polycarbonate lenses but with higher quality optics, and thus provides clearer vision.

[Layne Eyeglasses]

An aspheric lens or asphere is a lens whose surfaces have a profile that is rotationally symmetric, but is not a portion of a sphere.[1] In photography, a lens assembly that includes an aspheric element is often called an aspherical lens.

The asphere's more complex surface profile can reduce or eliminate spherical aberration and also reduce other optical aberrations compared to a simple lens. A single aspheric lens can often replace a much more complex multi-lens system. The resulting device is smaller and lighter, and possibly cheaper than the multi-lens design. Aspheric elements are used in the design of multi-element wide-angle and fast normal lenses to reduce aberrations. They are also used in combination with reflective elements (catadioptric systems) such as the aspherical Schmidt corrector plate used in the Schmidt cameras and the Schmidt-Cassegrain telescopes.

[Layne Eyeglasses]

Acrylic is a useful, clear plastic that resembles glass, but has properties that make it superior to glass in many ways. Common brands of high-grade acrylic include Polycast, Lucite and Plexiglass.

There are two basic types of acrylic: extruded and cell cast. Extruded or "continuous cast" acrylic is made by a less expensive process, is softer, can scratch easier and may contain impurities. Cell cast acrylic is a higher quality acrylic and U.S. domestic cell cast is a good choice for applications that require the best. Imported cell cast acrylic is often manufactured to lesser standards.

[Janae Eyeglasses]

Most optical use plastic acetate material for lenses. Polycarbonated lenses and high impact lenses are also made.