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A contact lens is a small, shell-shaped device of plastic, or similar material,' in
the form of a lens that is in contact with the cornea and which serves as a new
anterior surface of the eye. The capillary attraction of the liquid tear layer
between the contact lens and the cornea and the partial coverage of the lens by
the eyelids prevents contact lenses from being dislodged during eye movement
and blinking. While their main purpose is correction of vision deficiencies,
contact lenses are also used to change the colour of eyes and in the medical
treatment of certain eye diseases and injuries. With any kind of contact lens the
cornea's surface must be wet and oxygenated at all times to remain transparent
and healthy. The clinical performance of a contact lens is controlled by the
nature of the lens material, the lens design, the method and quality of
manufacture and the cleaning, disinfecting and wearing procedures used by the
patient.
Leonardo Da Vinci, in 1508, is claimed as one of the first proposers of contact
lenses. In 1636, Descartes illustrated a contact lens as one of his ways of
perfecting vision. However, it was not until the 1880's that a device that we
would recognise as a contact lens was developed. These contact lenses were
made of blown or moulded glass. These lenses caused serious discomfort to the
wearers and could not receive consumer acceptance.
