How Prescription Glasses Are Made
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Getting the Prescription
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Before glasses are made, a prescription must be determined. This is done at the doctor's office, where the person needing glasses undergoes eye tests (such as reading an eye chart). The results of these tests are compiled, and the doctor determines the prescription and sends it to the laboratory as part of an order. The patient also selects their preferred frames.
Creating the Lens
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All lenses begin as blank discs made of either plastic or glass, roughly 4 inches wide and between 1 and 2 inches thick. A lab technician takes the discs and, using a special machine, grinds the lens to the thickness matching the prescription order.
This process can take some time--it requires precision grinding, and the lens cannot be scratched. A single scratch, and the lens has to be discarded and the process begun again.
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Protecting the Lens
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After the painstaking grinding process, the lens is given a protective UV coating and a thin coat of an anti-scratch solution that protects the lens from dust and other small particles. During this process or shortly after, a groove is cut in the lens so it fits cleanly and snugly into the frame.
Framing
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The final series of tasks begins with the lenses being placed inside the frame of the glasses. The glasses then undergo a second round of checks to make sure there is no damage to the lenses and that they match the prescription order. If they're correct, the glasses are cleaned, packaged and mailed back to the doctor to be given to the patient. If not, the proper adjustments are made before being checked a second time. If they fail again, the glasses are scrapped and the process begins anew.
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