Prescription lenses are curved in such a way that light is correctly focused onto the retina of the patient's eye, improving vision. Some ophthalmic laboratory technicians manufacture lenses for other optical instruments, such as telescopes and binoculars. Ophthalmic laboratory technicians cut, grind, edge, and finish lenses according to specifications provided by dispensing opticians, optometrists, or ophthalmologists, and may insert lenses into frames to produce finished glasses. Although some lenses are still produced by hand, technicians increasingly use automated equipment to make lenses. Ophthalmic laboratory technicians should not be confused with workers in other vision care occupations.
Ophthalmologists are physicians who perform eye surgery.
Dispensing opticians, who may also do work described here, help patients select frames and lenses, and adjust finished eyeglasses. Ophthalmic laboratory technicians read prescription specifications, then select standard glass or plastic lens blanks and mark them to indicate where the curves specified on the prescription should be ground. They place the lens into the lens grinder, set the dials for the prescribed curvature, and start the machine. The lens is then placed in a polishing machine with an even finer abrasive, to polish it to a smooth, bright finish. Next, the technician examines the lens through a lensometer, an instrument similar in shape to a microscope, to make sure the degree and placement of the curve is correct.