Single vision lenses
These are the simplest and least expensive lens style.
A bifocal lens is used to provide vision at both distance and near.
By adding a third lens the eye glasses enable focusing on objects that are in your mid-range -like a cell phone.
Sometimes called "no-line bifocals,” these glasses provide the most complete solution to focusing at different distances.
Polycarbonate lenses provide ultraviolet protection. These lenses have become the standard for safety glasses, sports goggles and children's eyewear. Because they are less likely to fracture than regular plastic lenses, polycarbonate lenses also are a good choice for rimless eyewear designs where the lenses are attached to the frame components with drill mountings.
Trivex lenses provide ultraviolet protection. They are made from a newer plastic with similar characteristics of polycarbonate lenses. It is lightweight, thin and impact-resistant and may result in better vision correction than the polycarbonate lenses depending on personal preferences.
High index plastic lenses:
High-index plastics allow for thinner lenses. The lenses may not be lighter, however, due to the increase in density vs. mid- and normal index materials. Aside from thinness of the lens, another advantage of high-index plastics is their strength and shatter resistance, although not as shatter resistant as polycarbonate. This makes them particularly suitable for rimless eyeglasses.
Photochromic lenses are eyeglass lenses that darken automatically when exposed to sunlight, then fade back when you return indoors. In most cases, photochromic lenses are clear (or nearly clear) indoors and darken to a medium sun tint outdoors.
Light reflected from water or a flat surface can cause unwanted glare. Polarized lenses reduce glare and are useful for sports, out door activities, and driving.