Bifocaal

Bifocaal refers to eyeglasses or contact lenses that have two distinct optical powers. This is typically used to correct presbyopia, an age-related condition where the eye's natural lens loses its flexibility, making it difficult to focus on near objects. The lens is divided into two sections, with the upper portion usually designed for distance vision and the lower portion for near vision.

The design of bifocal lenses allows individuals to switch their gaze between these two zones to see clearly at different distances without needing to change their spectacles. The line separating the two segments is visible in traditional bifocal glasses, which can be aesthetically unappealing to some users. The power change between the distance and near zones can be abrupt.

Variations of bifocal lenses exist, including fused bifocals where the near segment is bonded to the main lens, creating a smoother surface. Segmented bifocals have a visible line where the two lens powers are joined. The development of multifocal lenses, such as trifocals and progressive lenses, offered more gradual transitions between different focal powers, providing a more seamless visual experience for some individuals. However, bifocals remain a common and effective solution for presbyopia.