Bifocal & Trifocal Lenses

Bifocal Lenses

Bifocal lenses have two distinct optical zones separated by a visible "seg" line. The upper portion corrects distance vision; the lower portion — the add segment — corrects near vision for reading and close-up tasks.

Types of Bifocal Segments

• Flat-top (FT-28/FT-35): The most common style. A flat-topped D-shaped segment in the lower half. Clear, defined transition between zones.
• Round segment: A circular reading zone. Less visible line, slightly less near-area width.
• Executive (E-style): The full bottom half of the lens is the reading zone. Maximum reading width.

Trifocal Lenses

Trifocal lenses add a third intermediate zone between the distance and near segments — typically at arm's length (60–80cm), ideal for computer screens. They feature two visible lines separating the three zones.

• Upper zone: Distance (driving, TV, general use)
• Middle zone: Intermediate (computer, dashboard, shelves)
• Lower zone: Near (reading, close-up work)

Bifocal vs. Progressive

Bifocals have a visible line and an abrupt power shift — some wearers find this jarring. Progressives eliminate the line with a smooth gradual transition, but require an adaptation period. Bifocals are generally easier to adapt to and are preferred by some experienced multifocal wearers.