Posted on August 27 2015
For most people, getting a pair of glasses involves going to an eye-care professional to get a prescription and selecting a pair of frames. Then in a few days, the customer returns to the optical store to pick up their glasses. Have you ever wondered what happens during that time? How exactly is a pair of prescription glasses made?
During an eye exam, the eye-care professional will test your eyes to determine what sort of vision correction you need. Once this prescription is written, it will usually go to an optical laboratory, where the glasses are assembled. Depending on what sort of prescription you have and what type of frames you have chosen, a technician will select a certain lens blank and begin customizing the lens to your prescription. Lens blanks are regular lenses without any vision correction. The back of the lens blank is flat and the front side is curved. An optical laboratory will stock many types of lens blanks in a variety of materials – glass, plastic, polycarbonate and others – in order to have the right lens blank to match each customer’s prescription and frame selection. During Surfacing, the lab technician grinds down the lens blanks (usually with a diamond-edged tool) on the concave side to match the vision correction that you need. While in Surfacing, the lenses will also be smoothed, polished, cleaned and inspected.
After Surfacing, the lenses go the Finishing step, which is where the lenses are adjusted so they will fit into the frames you have selected. A technician uses a machine to edge the lenses into the exact size and shape necessary to match the frames. During the process, a thin edge is left around the lens so that it will fit securely inside the frames. This step is called beveling. If you have selected any tint or coating on your lenses, such as UV protection, these are applied next by the Finishing department. The lenses are checked again to make sure they have the proper prescription. In order to get the thin lenses to fit exactly inside the frames without cracking or later coming loose, the lenses are often heated, making them temporarily a bit more pliable. Once the glasses are assembled, there’s another inspection to make sure the vision correction of the glasses matches the prescription and that the frames and lenses have no imperfections. The glasses are then cleaned and packed for shipping to the optical store, where an optician can make fit adjustments when you come to pick up the glasses.
As you can tell, making a pair of prescription glasses is quite involved. Although technology and years of expertise has made the whole process more streamlined, it still requires a great deal of precision from the laboratory opticians to correctly make a pair of glasses. Even the smallest error will ruin the prescription. So the next time you pick up glasses, you will know all the steps needed to help you see clearer.