What is the single point of the lens around which the lens is cut and edged known as?

The single point of the lens around which the lens is cut and edged is known as the optical center. This critical point is central for determining how light passes through the lens and is crucial for ensuring that prescriptions are accurately oriented when mounted in frames. The optical center is defined as the point at which light rays converge and are directed correctly for optimal vision.

In the case of the other options, while terms like mechanical center, geometric center, and edge center may refer to other aspects of lens construction or positioning, they do not accurately describe the specific point where the lens is designed to provide the best optical performance. The mechanical center may relate to the physical characteristics of the lens's weight distribution, the geometric center pertains to the mid-point of the lens's physical dimensions, and edge center would typically describe the location at the lens's perimeter, which is not functionally relevant to the lens's performance in correcting vision. Understanding the significance of the optical center helps opticians ensure that lenses provide the intended visual clarity and comfort for the wearer.