multifocals

Multifocals are vision lenses designed to provide more than one focal power in a single lens, enabling clear sight at distance, intermediate, and near distances. They are commonly used to correct presbyopia, a age-related decline in the eye’s ability to focus up close, and may be prescribed for people who require different prescriptions for different viewing distances.

Eyeglass variants include bifocals, trifocals, and progressive lenses. Bifocals have two distinct optical zones separated by a visible line, typically for distance and near vision. Trifocals add a third zone for intermediate vision. Progressive lenses, or varifocals, offer a gradual, continuous change in lens power from top to bottom without visible steps, providing a seamless range of vision. In addition to eyeglasses, multifocal designs are available in contact lenses, using concentric zones or aspheric designs to deliver simultaneous vision.

How multifocals work varies by design. Simultaneous-vision lenses present multiple focal powers at once, so the brain learns to select the appropriate image. Progressives provide a continuous power gradient, which can reduce the abrupt transition seen in segmented lenses but may introduce peripheral distortions. Adaptation can take days to weeks and depends on frame fit, posture, and habitual viewing tasks.

Fitting and care are important for optimal performance. Proper frame height, lens alignment, and fitting by a clinician are crucial to minimize distortion and eye strain. While convenient, multifocals may be less suitable for activities requiring precise, rapid focusing or for new wearers during the adjustment period.

Historically, Benjamin Franklin is credited with popularizing bifocals, while progressive lenses emerged in the mid-20th century and became widespread in subsequent decades.