Over 100 million Americans wear some form of corrective
Recently, on NPR, Ira Flatow interviewed Dr. Larry Enright, who is currently the general manager at PerfeRx Optical, an optical laboratory based in Massachusetts which makes eyeglass lenses. Here are some of his insights into how they create the science of sight:
1. The lab receives a hockey puck-shaped chunk of plastic called a 'lens blank' from their supplying factory. The blank is then crafted by pouring molten plastic into different molds. Each mold has its own distinctive curve in order to make it easier to grind that particular prescription.
2. The prescription is defined by the curve on the front of the lens and the back of the lens added together. For example, if a patient has a prescription of +1.00 and the blank from the factory has a curve of +5.00 on the front of the lens, the optical lab technician would put a curve of -4.00 into the back lens with a lathe generator.
3. After adjusting the curve of the lens, the technician is now in possession of something that looks like a huge contact lens. Then, they will cut down the (currently huge) lenses to match the size of the frames you have already chosen.
4. Lastly, since lenses are generally carved with a diamond-embedded blade (for sharpness, accuracy and durability), it needs to be polished as it goes through the manufacturing process. A treatment consisting of cold water and a soft felt pad give the lens a much smoother finish creating a better final product.