Optics
The science of Optics has been around a long time. Mathematicians have been able to describe the way light moves through lenses, and the inherent distortions produced, since the 16th century. While the mathematics was understood, manufacturing ability didn’t allow for eyeglass lenses to be made optimally.
Lens Technology
Until the mid 1980s, eyeglass lenses were based around Zeiss, “Punktal”, technology introduced in 1912. These lenses carefully chose the front surface curvature of the lens to maximize the clear field of view through the glasses. In 1959, Essilor brought the first progressive lens to the market. It combined front surface moulding, allowing the incorporation of a reading correction, with conventional grinding and polishing of the inside surface. As plastic lens materials began taking over the market in the 80s, front surface moulding techniques improved. Aspheric design, where the front surface of the lens flattens towards the periphery, was incorporated into progressive design. This flattening improved the peripheral vision, and soon became available in single vision lenses as well. These lenses all used conventional spherical grinding and polishing technology.
In the last 20 years, using a computer-controlled lathe to produce the curves on the lens, has gradually been replacing conventional manufacturing. This is often referred to as digital surfacing. The advantage of digital surfacing is that optimal power can be calculated at various points across a lens surface, and then reproduced by the lathe. Most of the so called, “digital”, designs use standard, or average measurements to calculate powers. The more advanced designs, both single vision and progressive, use actual measurements from the patient with the frames they have chosen. This allows for more accurate, personal calculation to be designed into the lenses produced. The best designs use thousands of calculations over the surface of each lens to produce the clearest, widest fields of view possible.
