varifokal

Varifokal is a term used in several Scandinavian languages (notably Danish and Norwegian) to refer to progressive eyeglass lenses, also known as varifocal lenses or progressive addition lenses. These lenses provide multiple focal powers in a single lens without visible horizontal lines, and they are commonly used to correct presbyopia.

How they work: A varifokal lens gradually changes its optical power from the top to the bottom of the lens along the vertical axis. The top portion is optimized for distance vision, the middle zone for intermediate tasks such as computer work or dashboard viewing, and the bottom portion for near tasks like reading. The addition power—the amount of extra focusing strength added for near vision—varies with prescription, typically ranging from about +1.00 to +3.50 diopters.

Design and manufacturing: Traditional progressives use a continuous surface, while modern digital or freeform progressives are customized to the wearer’s eye measurements, including pantoscopic tilt, frame wrap, and pupillary distance. Frame choice and lens corridor height influence field of view and comfortable near work; higher and wider corridors generally offer more usable intermediate and near areas.

Advantages and challenges: Varifokals avoid visible lines and provide seamless vision across distances, supporting many daily activities. They can demand an adaptation period and may cause peripheral distortion, especially in the upper or lower parts of the lens. Proper fitting, frame selection, and practice help mitigate these effects.

Care and materials: Lenses are available in various materials (plastic CR-39, polycarbonate, and high-index) with coatings for anti-reflection, scratch resistance, and blue-light filtering. Regular cleaning with a microfiber cloth maintains clarity.