Lenses come in two basic styles: single vision and multi-focal. A single vision lens is prescribed for a person who only needs distance or near correction, with or without astigmatism. A multi-focal lens can be a bifocal, trifocal or progressive style.
Single vision lenses are the least expensive because they only have one focal area. Multi-focals have two or more focal areas, and are for those who need distance as well as near correction. Bifocal lenses have a distance power on top, and then a lined segment that contains the reading power below. A trifocal has an additional intermediate distance, resulting in a lens with two lines. A progressive lens, also called PAL’s or no-lines, have many focal areas, allowing the wearer to see near, far, and most points in-between with ultimate clarity.
In addition to focal styles, lenses also come in different materials. Lenses are available in glass or plastic, as well as many light-weight or safety options. If you have a heavy prescription or are bothered by regular sunglasses due to the weight, you should choose a light-weight lens. Polycarbonate is a popular light-weight material, and has the additional benefit of shatter-resistance, making it an ideal lens for safety glasses, children or athletes.
Lenses can also have coatings applied to make then scratch-resistant (no lens is scratch-proof!), filter ultra-violet rays and reduce glare. All three of these options are recommended for every pair of glasses, as they improve the safety and performance of the lenses. Additionally, lenses may be tinted, polarized, mirror-coated, or made to darken outdoors and lighten indoors. A conversation with your optician about your needs and lifestyle can lead you to choosing the right options for your first pair of glasses.
Choosing the right frame can be the difference between glasses that live on your nose and glasses that live in a drawer. A good frame should be lightweight, strong, fit comfortably and suit the wearer’s sense of style.