A bifocal lens is a type of eyeglass lens that contains two different prescriptions in one lens. It is used to correct two different vision problems, typically presbyopia and myopia or hyperopia.
Presbyopia is a condition that commonly occurs as people age, in which the eye loses its ability to focus on nearby objects. Myopia (nearsightedness) and hyperopia (farsightedness) are conditions in which the eye has difficulty focusing on distant or nearby objects, respectively.
A bifocal lens typically has a distinct upper and lower portion, with the upper part of the lens containing the prescription for distance vision and the lower part containing the prescription for near vision. The two parts of the lens are separated by a visible line called the “bifocal line.”
Bifocal lenses were first developed in the 18th century by Benjamin Franklin, who was himself presbyopic and found it inconvenient to switch between two pairs of glasses for different tasks. Today, bifocal lenses are commonly used in eyeglasses and contact lenses to provide vision correction for multiple vision problems in a single lens. Read More about School Analytics.