How Eyeglasses Are Made
Eye glasses are specially crafted lenses made to fit inside frames designed to hold them, and are useful in correcting or greatly enhancing a person’s vision. In discussions on how eye glasses are made, many often believe that the precursor of eye glasses was the magnifying glass. However, the history leading to the invention of eye glasses actually extends a lot further.
Anyone truly curious about how eye glasses are made may be interested to know that, as early as 4 BCE, people are believed to have used water to enhance or enlarge the appearance of small items that they wished to view more closely. It has also been noted that the Roman philosopher Seneca used a specially crafted water-filled orb to magnify the print contained in the many books he read. More than one thousand years later, Italian craftsmen produced solid glass lenses similar to today’s magnifying glasses to assist people with poor or declining vision. Variations of this design progressed over several years until the first eye glasses actually worn on the bridge of the nose were produced in Italy circa 1285. It is Benjamin Franklin who was ultimately credited with the invention of the bifocal lens useful in vision correcting. Franklin’s invention actually led to the type of eye glasses that are commonly worn today.
Contrary to the name, today’s eye glasses are most often made of plastic. Prior to the 1950s, eye glasses were still being made with glass, but newer uses of plastic since then have proved to be a lighter, more comfortable choice for those who wear eye glasses.
In the United States, the Food and Drug Administration (FDA) and the American National Standards Institute (ANSI) strictly regulate the standards by which eye glasses are made. To assure that these standards are met, all manufacturers licensed to make eye glasses are also required to be members of the National Optical Association, which further enforces the rigorous standards of the FDA and the ANSI.
The exact science of how eye glasses are made involves a very precise, very detailed system of events. After a patient’s eyes are tested to determine whether or not eye glasses are needed, if it is determined that eye glasses will be prescribed, a technician then has the task of figuring out the patient’s necessary prescription strength. A special computer is used in determining this and it prints the exact specifications for how to manufacture the prescribed lens for the patient’s eye glasses.
The physical creation of the prescribed eye glasses then involves the technician comparing a pair of plastic blanks until an appropriate one is found for the patient’s prescription. The remaining prescription strength needed is then ground into the blanks at the back of the lens.
Next is the blocking process, which is when the optical center of the eye glasses is located. More grinding sets the necessary degrees or curves that are needed to achieve the optical strength that the eye glasses need. The lens is then shaped or beveled, and polished to perfection.
While different types of plastics are used in making glasses, a very lightweight polycarbonate known as “Featherweight” is the most durable, the most popular, and the most expensive. Also, if a patient prefers tinted eye glasses, the lenses are specially treated before being finally inserted into whichever frames the patient has selected.
Because of advances in technology and the materials used, today’s eye glasses are much more durable than in years past, and many people even regard them as fashion accessories.