About the Process for Making Contact Lenses

Contact lenses are small, circular lenses placed over the eye to correct the user's vision. Contact lens trade groups say 125 million people in the world use contact lenses to correct their eyesight instead of using eye glasses. The process for making contact lenses is a precise science that needs to take into account the various levels of vision correction needed by contact lens users.

History

• The earliest mention of anything resembling a contact lens can be found in Leonardo da Vinci's study of the human eye in 1508. In 1636, French scientist René Descartes described something even more similar to the modern contact lens, though it wasn't until 1801 that a man named Thomas Young actually built an early version of the contact lens. These were all rough prototypes. But in 1929, a scientist created the first contact lens that resembled what is used today.

Types

• Contact lenses are made of plastic. Beyond that, you can choose between different types of contact lenses. There are hard contact lenses and soft contact lenses, as well as contact lenses that can be worn overnight and those that need to be taken out daily. Some people also wear cosmetic contact lenses, which don't provide vision correction but modify their eye color.

Features

• To make contact lenses, contact lens manufacturers take special contact lens plastic polymer and either mold it into a contact lens shape, or cut into contact lens form before the final manufacturing process.
  To mold contact lenses, a contact lens machine pours the melted plastic polymer into a curved contact lens mold and smashes it into shape using intense pressure. This shapes the contact lens into the right curves to fit the human eye. The mold squeezes the plastic until it cools, then transfers the molded contact lens to a special grinding process that smooths the edges of the contact lens.
  Alternately, contact lenses can be made by being cut out of the plastic polymer material by a laser. The laser cuts a circular, contact lens-shaped piece of plastic and slices it into a curve to fit the eye. The rough contact lens is then transferred to the finishing stage where a diamond polisher smoothes the contact lenses.
  Before lasers were used to cut the plastic to make contact lenses, contact lenses were made using either the pressure method or by using a lathe. The lathe would cut the plastic polymer into contact lens form. This method for making contact lenses is no longer as common now that contact lenses are made with either pressure molds or lasers.

Considerations

• For safety purposes, all contact lenses are individually inspected by humans or by a computer. After contact lenses have been made, they are also put in a solution to sterilize them before being packaged.

Warning

• People who wear contact lenses sometimes experience health problems associated with the contact lenses. If worn improperly, contact lenses can also damage the eye or cause vision problems. Thus, it is important that contact lens users follow the directions for their contact lenses, such as not wearing single-use contact lenses overnight. Hands should also be washed thoroughly before inserting or removing contact lenses.