How Are Contact Lenses Produced?

Material

Contact lenses are formed out of plastic polymers. Soft contact lenses use poly hydroxyethyl methacrylate while hard contact lenses use polymethyl methacrylate. The materials are either cast in a mold or cut in a lathe to make contact lenses.

Molding

Molding is one of the major manufacturing methods used to make contact lenses. The chemicals are either poured or injected into a mold that is in the shape of the lens. Through a combination of cooling, spinning, and polishing, the contact lenses are created.

Lathing

The other major manufacturing method used to make contact lenses is cutting them on a lathe. Contact blanks are cut out and placed on a lathe. The blank is then spun around at high speed as a laser or diamond cuts the contact lens blank into the proper shape. Once the desired shape is achieved, the contact lens is then polished on the spinning lathe. Some molded contacts are later polished on a lathe.

Finishing

Contact lenses must be finished before they are ready to wear. This process involves very tiny cuts in the lens to fit the eyeball and adjust for the power of each lens. This is done on a grinding machine with emery paper or a razor blade. The contact lens is then trimmed down to the proper size.

Inspecting

Contact lenses are carefully inspected before they leave the factory. They are examined with magnifying devices to make sure that they are smooth, are the correct size, and fit to the proper curvature. Computers are often used to assist in this process.

Cleaning

Once contact lenses are crafted, they must be cleaned. The contact lenses are sterilized by boiling them in salt water for several hours. This also has the effect of making them softer and more malleable for the eye.

Container

Contact lenses are placed in sterile containers for shipping and sale. These can be tiny glass jars or plastic sleeves with peel away tops. The contact lenses are submerged in saline solution inside the container. This liquid mimics human tears. The saline solution keeps the contact lens moist and supple. This way they can be removed from the container and used immediately.