Bifocal lenses can be made of either glass or plastic. ... First, the back surface of the additional lens is ground and polished. Then, the curved side is placed in the existing indentation of the main lens. Now the additional lens is melted and ground together with the main lens until only a single lens is visible.

How are bifocal lenses made?

How Are Bifocal Glasses Made? Most bifocals start with the primary lens prescription, the one you need for general distance viewing. Another lens with a different prescription is then applied to the bottom of each original lens, resulting in a surface with two different prescriptions.

Are lined bifocals better than progressive?

The larger viewing area is for distance and the smaller viewing area is for reading. ... With lined bifocals, you are better able to see people, objects, and even text at long distances. In addition to this distance benefit, lined bifocals contain less distortion on the edges of your lenses.