- About 34 million people wear contact lenses. The very first contact lenses were made of glass; then hard lenses came along. In 1971, the first soft contacts hit the market. Soft contacts are made of silicone, a soft plastic that allows oxygen to flow through the lenses. Since then, soft contacts have been the contact of choice.
- There are a few different ways in which contacts are created. The most commonly used method is called cast-molding. In this process, the polymer mixture is in liquid form and is poured into a two-part mold. (Polymer is a thin plastic that is curved and clear.) This mold is then pressed and molded to a specific lens' power, curvature, diameter and edge. The lenses are then cured, or heated, to take a solid form. The lenses are then packaged in small plastic containers that contain saline, which is similar to human tears.
- In the lathe-turning or lathe-cutting process, the contacts are cut and polished on a CNC lathe. A lathe is a machine commonly used to smooth or carve metal or wood. A lathe spins the material while it cuts and polishes the material to the desired shape. A CNC lathe cuts and shapes contacts. This process can produce over 1,000 contacts a day.
- In spin-casting, much like in cast-molding, the polymer is poured into a mold while in a liquid state. In spin-casting the contacts are spun into the desired dimensions.
- Although soft contacts are all oxygen-permeable, some are specifically made to allow as much oxygen in as possible. The liquid polymers are solidified into rods and then cut into what are called buttons. A computer-generated lathe is then used to cut and shape the contact. The process allows the contacts to be made to a specific curvature that matches that of the cornea.
