The most basic is the eyeglass lens. The eyeglass lens is by far the best in absorbing ultraviolet light. It comes in several different colors and is, of course, scratch resistant. It is also one of the least expensive.
The downfall to the eyeglass lens is the weight of a pair of prescription glasses made of glass. They are also very breakable and have to undergo a heat-treated process to ensure durability.
I think resin plastic is another type of material used in manufacturing the prescription eyeglass lens. They are the lightest of all lenses, but do not offer the high level of protection against ultra violet light that the other lenses offer.
There is still another material used to manufacture prescription glasses is the High-Index plastic lens. It also absorbs ultra violet light well. This type of lens is much lighter in weight than the eyeglass lens; however, they are also very expensive and can be scratched very easily.
Some prescription glasses are tinted with a wide variety of colors and shades. The purpose of the tint is to reduce the glare from certain situations: such as bright lights, computers television sets, etc. Another reason for the tinting of the lenses are to offer comfort to the eyes. Also, people order tints on their eyeglasses for the fashion.
Eyeglass and most plastic lenses are coated with a UV protection coating. Ultra violet rays can cause severe damage to the eyes. It is very important to protect your eyes while out in the sun.
Another coating that is added to a pair of prescription eyeglasses is the scratch-resistant coating. Sometimes this coating is applied at the manufacturer and other times it can be added right there at the eye doctors office.
It must be said, however, that even while this coating can aid in the durability of the lens, it does not make the lens scratch proof