For many of us, we put on a pair of glasses or readers on our faces every single day. Most of us wear them to help us see, while others wear them as fashion accessories. No matter how we use glasses, have you ever wondered how the actual lenses are made for your desired prescription?
Back in the 1200s when the magnifying glass was first invented, the lens was made from a transparent quartz or beryl material. As demand grew, eventually that was replaced with glass.
Since the 1950s through today, the majority of glasses lenses you see and wear are made from plastic. They are lighter and less prone to break compared to previous methods, such as glass.
There are many stages that go into producing glasses lenses. That includes fine grinding of the plastic, polishing, shaping and coating.
When the plastic is received in the lab, it comes in round pieces, similar to hockey pucks in thickness. At this point the material is called a lens blank.
The lens blank is than surfaced using computer settings. During this process a machine shaves layers of material off the back side to create a custom, precise curvature. The curvature determines how the lens will bend the light rays to correct the various degrees of opias – myopia, hyperopia, presbyopia and astigmatism.
Once the surfacing is complete, the lens goes through a fining process to polish the lenses. It is than cut into size using an edging technique. Finally a coating process is applied to the lenses for various reasons such as scratch resistant coating to a coating to block reflection and UV light. In addition to the plastic, adhesive tape, metals, dyes and tints are also used to create the lenses.
Most consumers just see the finished product that look great in a pair of frames. Now though, if someone asks, you can tell them how exactly those lenses they are wearing were created.