Which type of lens design allows for continuous change in prescription strength?

Progressive lenses are specifically designed to provide a smooth, continuous transition in prescription strength across different viewing distances. Unlike bifocal lenses that have distinct segments for near and far vision, progressive lenses offer a gradient of increasing lens power. This means that as the wearer looks from the top of the lens down to the bottom, they encounter gradually changing prescriptive strengths, which accommodate vision for distance, intermediate, and near tasks seamlessly. This design is especially beneficial for individuals with presbyopia, as it allows for a more natural visual experience without the abrupt change that bifocals can cause.

In contrast, bifocal lenses only cater to two distinct viewing distances, and single vision lenses offer only one prescription type that does not adapt for different distances. Polarized lenses do not focus on prescription changes at all; instead, they are primarily designed to reduce glare from reflective surfaces, making them useful for outdoor activities but not for addressing visual accommodation needs.