The lens “blanks” used to make prescription lenses have a frontal curvature referred to as the “base curve.” The total power of the lens is equal to the sum of the front surface curvature and the back surface curvature of the lens. Thus, the lens curvatures can be varied, but the power of the lens can be kept constant. For any prescription, the lens can be made with different base curves; however, if the curve of your new eyeglass lenses is different from what you are used to, it can make the world look curved or bowed. If this is a problem with your new eyeglasses, it may necessitate a change back to your more familiar base curve. Modern lenses come in a variety of materials. The key to a successful lens prescription is the proper location of the optical centers of the lenses. A fundamental element that makes wraparound eyewear look so sleek is the steep 8-base curve of the lenses.
Nov 18, 2011