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Object lesson No 89 Contact lenses

A friend who had been peering through the same scratched pair of glasses for years was persuaded to try contact lenses. She squirmed, blinked, stared, pointed to a wall and exclaimed "Bricks!" We went for a walk, and it was like taking a baby out into the world. She looked up. "The Moon!" And down: "Wow, grass!" She never looked back.

Contact lenses are a relatively new invention, but not a new concept. That old visionary Leonardo da Vinci squeezed a few sketches of some in between his drawings of helicopters and hovercrafts. Rene Descartes, in 1632, also spotted their potential. Neither actually made eye contact, leaving that sensitive operation to an Englishman called Thomas Young.

In 1801, Young filled a 3mm glass tube with water, put a microscopic lens in the outer end, and then inserted the whole lot into his eye. Despite this brave effort, credit for the first use of contacts is generally given to the German physiologist Adolf Fick. Fick experimented on animals before using glass lenses in 1887 to fix a patient's astigmatism.

Fick's lenses were functional, but uncomfortable. Ordering a pair was no fun either, as doctors had to take an impression of the eyeball to ensure the lenses would fit. It was another 60 years before machines were introduced to measure the curvature of the cornea.

Around then, in 1948, Kevin Tuohy, a Californian optician, developed the first modern contact lenses. Made of hard plastic, these floated on a film of tears. Tuohy's lenses may have been better than glass, but they still felt like driftwood. Soft plastic lenses made out of a water-absorbing gel came along, courtesy of the Czech chemist Otto Wichterle, in 1961.

Contacts work like spectacle lenses, refracting or bending light so that it converges perfectly on the retina. They can fix short- and long-sightedness, the presbyopia that often comes with old age, and even the desire to turn brown eyes blue.

Opticians will supply customers with daily disposables, bifocals, multifocals, multifocal disposables, UV-absorbers and, most recently, lenses that are worn at night and temporarily reshape the cornea. Blinking marvellous.

Stephanie Northen

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