CR-39 (good optics and scratch-resistance)

CR-39, or allyl diglycol carbonate (ADC), is a plastic polymer commonly used in the manufacture of eyeglass lenses. The abbreviation stands for "Columbia Resin #39".

Polycarbonate (providing good impact-resistance for sports frames)

Polycarbonate lenses are up to 10x more impact-resistant than plastic or glass lenses and they provide 100% protection from the sun's harmful UV rays. They're also lightweight, adding to the comfort of your eyeglasses, sunglasses and sports eyewear.

Trivex (superior optics and impact resistance at a slightly-higher price point)

Like polycarbonate lenses, Trivex lenses are thin, lightweight and much more impact-resistant than regular plastic or glass lenses. Trivex lenses, however, are composed of a urethane-based monomer and are made from a cast molding process similar to how regular plastic lenses are made. This gives Trivex lenses the advantage of crisper optics than injection-molded polycarbonate lenses.

1.6 Index (for entry-level thinner lenses)

High-index lenses are the right choice if you want thinner, lighter lenses and eyeglasses that are as attractive and comfortable as possible. They're especially recommended if you have a strong eyeglass prescription for nearsightedness, farsightedness or astigmatism. They can make your eyeglasses noticeably slimmer, lighter and more attractive, regardless of how strong your prescription is.

1.67 Index (a mid-level lens that’s 10% thinner than a 1.6 lens)

High-index plastic lenses are now available in a wide variety of refractive indices, typically ranging from 1.53 to 1.74.

1.74 Index (the thinnest resin lenses made)

High Index 1.74 lenses are the thinnest, flattest and most cosmetically appealing lens ever developed. These ultra-thin lenses are nearly 50% thinner than plastic and 5% thinner than 1.67 high index lenses, offering the ultimate in technology and cosmetics. The thinner lens is much more flattering, reducing the distortion that high prescriptions cause when made with lower-quality lenses.

Progressive (provides a smooth transition between parts with different focal lengths, correcting vision at all distances)

Progressive lenses are no-line multifocal lenses that look exactly the same as single-vision lenses. They help you see clearly at all distances without annoying (and age-defining) "bifocal lines" visible with bifocals and trifocals. Progressives have many more lens powers than bifocals or trifocals, with a gradual change in power from point to point across the surface of the lens.