Editing Corrective lens (section)

===Bifocal===
[[File:Bifokalbrille (fcm).jpg|thumb|These [[bifocals]] are upside down as they rest on the surface. The add segment of the lens for near vision is the D-shaped area.]]
A [[bifocals|bifocal]] is a lens with two sections, separated by a line (see image to the right).  Generally, the upper part of the lens is used for distance vision, while the lower segment is used for near vision. The area of the lens that caters to near vision is called the add segment. There are many different shapes, sizes, and positions for the add segment, such as rounded bifocals and D segment bifocals, that are selected for functional differences as well as the visual demands of the patient. Bifocals allow people with [[presbyopia]] to see clearly at distance and near without having to remove the glasses, which would be required with single vision correction.