Varifokals

Varifokals, also known as progressive lenses, are eyeglass lenses that provide multiple focal powers in a single lens to correct presbyopia. They combine distance, intermediate, and near prescriptions with a seamless, gradual change in power from the top to the bottom of the lens, avoiding the visible lines found in some older multifocal designs.

The progression of optics is achieved through a specially designed surface that blends three zones: distance at the top, intermediate in the middle, and near at the bottom. The amount of power changes gradually rather than in stepped segments, which reduces line visibility and image jumps but can introduce peripheral distortion, especially toward the edges. Lenses vary in corridor length and field of view; common variants include standard progressive, short-corridor, and executive designs, with aspheric surfaces to help minimize aberrations and improve peripheral clarity.

Fitting and adaptation are important for comfort and clear vision. Accurate measurements of pupillary distance, pantoscopic tilt, and fitting height are essential. Users may experience an adaptation period during which distortion, dizziness, or the need to move the head rather than the eyes may occur. Frame choice matters; frames should provide enough vertical space to accommodate the progressive blend and allow natural head movements.

History and technology have evolved since the 1950s, when progressive lenses were developed to replace bifocals. The term varifocal is widely used in various markets, and Varilux is a well-known brand associated with progressive designs. Modern varifokals often employ high-index materials, lighter lenses, and advanced coatings such as anti-reflective, scratch resistance, UV protection, and blue-light filtration.

Materials and care: Common lens materials include CR-39 plastic, polycarbonate, and high-index plastics. Proper cleaning and storage extend lens life, and coatings should be maintained to preserve optical quality.