Development of contact lenses and their worldwide use.

The concept of applying a lens to the cornea as a refractive appliance was first proposed in the early 19th century. By 1888, glass scleral lenses for the correction of optical defects and irregularities were manufactured and used. New materials, especially soft hydrogel lenses and rigid gas-permeable lenses, became available in the 20th century and allowed comfortable contact lenses to be made in any design needed.