What is the primary difference between aspheric and concentric lens designs?

The primary difference between aspheric and concentric lens designs lies in the way the curvature of the lens changes. Aspheric lenses are characterized by a gradual change in curvature across the surface of the lens, allowing for a smoother transition in optical power. This design minimizes distortions and aberrations, particularly in higher refractive errors, providing better visual quality, especially for patients requiring correction for presbyopia or other vision issues.

On the other hand, concentric lenses feature designs that consist of multiple zones or rings, each with distinct optical properties. These designs typically have a more abrupt change in power from one zone to another rather than a smooth transition. As a result, concentric lenses may not adjust as seamlessly to varying visual distances, which can lead to more noticeable visual disturbances.

This distinction is vital for practitioners when deciding which lens design to use based on a patient's needs, as aspheric lenses tend to offer a more comfortable visual experience, especially for those who require a broader range of vision.