What term is used to describe the smooth junctures between curves on the posterior surface of a lens?

The term used to describe the smooth junctures between curves on the posterior surface of a lens is "blends." In the context of lens design, blends refer to the seamless transitions between different curvatures or surfaces, which contribute to the overall optical performance and comfort of the lens wearer.

When the curves are smoothly blended, it helps to minimize abrupt changes in the surface profile, reducing optical distortions and ensuring that light passes through the lens in an uninterrupted manner. This is essential for creating lenses that not only allow for clear vision but also enhance wearer comfort, especially in high prescription or multi-focal lenses.

Understanding the concept of blends is crucial for anyone involved in lens fabrication and fitting, as it directly impacts the lens’s functionality and the user's visual experience. Other terms like edges, curvature, and transitions may describe different aspects of lens design but do not specifically refer to the smooth junctures between curves. Edges refer to the outer boundary of the lens, curvature describes the profile of the lens surfaces, and transitions might imply a change but not necessarily the smoothness involved in blending curves.