BIFOCAL Meaning and
Definition
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Bifocal refers to a type of eyeglass lens that contains two distinct optical powers. It is commonly used to correct both near and far vision problems, specifically for individuals diagnosed with presbyopia. Presbyopia is an age-related condition where the eye's lens loses its flexibility, making it difficult to focus on close objects or small print.
The bifocal lens is designed to overcome this issue by incorporating two different sections within the lens. The upper part of the lens is utilized for distance vision, providing a clear view of objects located far away. Meanwhile, the lower part of the lens is specifically crafted with a higher optical power to aid near vision. This lower portion is often shaped like a half-moon or a D-shape, commonly referred to as the "add power" or the "reading segment."
The transition between the distance and near vision sections of the lens may be demarcated by a distinct visible line, known as a bifocal line. This line helps the wearer position their eyes accordingly to utilize the appropriate section of the lens based on their current visual needs. However, modern bifocal lenses often employ more advanced designs, such as progressive or multifocal lenses, which seamlessly blend the different optical powers without any noticeable lines. These advanced bifocals offer a smooth transition between near and far vision zones, providing improved aesthetics and visual clarity for the wearer.
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Having two foci; noting a lens used in cases of presbyopia, in which one portion is suited for distant vision, the other for reading and near work in general.
A practical medical dictionary. By Stedman, Thomas Lathrop. Published 1920.
Common Misspellings for BIFOCAL
Etymology of BIFOCAL
The word "bifocal" comes from the Latin roots "bi-" meaning "two" and "focus" meaning "hearth" or "fireplace". The word was coined in the early 19th century by Benjamin Franklin, who invented bifocal lenses for eyeglasses. The term "bifocal" refers to the lenses having two distinct optical powers, allowing the wearer to see clearly at both near and far distances.
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