A pair of eyeglasses is normally consisted of two lenses and a frame. Rimless eyeglasses still have two temples and a bridge used to connect the lenses. It is commonly known that
eyeglass lenses are the critical section for the wearers to get normal vision. From a brief perspective, eyeglass lenses have prescription ones and non-prescription ones. While the first category is the majority in the market, the latter one is still popularly used. Non-prescription eyeglass lenses are sometimes called plain lenses, meaning they are not for vision correction. Dissimilar to prescription eyeglass lenses either concave or convex, non-prescription lenses are plain. These plain-surfaced eyeglasses lenses are used simply for fashion or eye protection. Utilizing plain lenses, there are regular sunglasses and protective goggles. These plain eyeglass lenses have long been existent for many years and will continue to stay in the market.
The other main category is prescription eyeglasses used for vision correction. They can either be convex or concave. The former type is capable of correcting hyperopia and the latter type is for myopia. These two types of non-plain eyeglass lenses help the nearsighted or farsighted eyes focus light entering the eyes properly. Even if there are popular contact lenses and eye surgical treatments, prescription eyeglasses have remained as an indispensable solution for many individuals. Using prescription eyeglass lenses is actually the simplest method. Compared with plain lenses, convex or concave eyeglass lenses are more complex and expensive.
Within the prescription lenses, there are still sub-categories, including single vision lenses and multifocal lenses. Suggested by the name, single vision eyeglasses are able to deal with only one vision problem. Regular prescription eyeglasses fall into this category. Until now, single vision spectacles have been the major role in the market. Individuals with nearsightedness or farsightedness are main participants of those single vision glasses. In addition, there are still multifocal eyeglass lenses, containing bifocals, trifocals and progressive ones. These eyeglass lenses are mainly for folks with presbyopia, who are still suffered by nearsightedness. It is easy to understand that multifocal eyeglass lenses can resolve more than one vision problem at the same time.
In fact, there are still many other aspects of eyeglass lenses, in addition to lens power or powers. Lenses for fashion can be applied with different colors. For extra lens feature or property, there are available various coatings. From a basic viewing point, eyeglass lenses can be made from glass or plastics.
