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The famous and versatile scientist, Leonardo Da Vinci first introduced
the general concept behind the invention of contact lenses.
He was more concerned about knowing the mechanism of eye accommodation
and explained how the power of the cornea can be changed by
immersing the eye in a bowl of water. It was only after three
centuries following this observation that contact lenses were
manufactured and used.
After Leonardo, in the early years of the 17th century, Descartes
proposed that corneal contact lenses be used to correct eyesight.
His idea involved using a glass tube filled with liquid and a
protruding end made of clear glass, which was to be positioned
directly with the cornea. This was, however, impractical as it
prevented blinking.
In the year 1801, Thomas Young built on Descartes’ proposal
to correct his own vision by using a water filled tube of glass
whose outer end was fitted with a microscopic lens and looked
like an eyecup. However, this did not rectify the problems of
light refraction.
The English astronomer Sir John Herschel came up with two ideas
of a sphere of glass filled with animal jelly and making a mould
of the wearer’s eye to fit exactly on the eye surface. However,
Herschel never put his ideas to action and it was really Dr. Dallos
who, much later, perfected the method of taking a mould from the
wearer’s eye to correspond to the actual shape of the eye.
The forerunner of the contact lenses used today was was developed
by a German named Adolf Fick who explained how afocal scleral
contact “shells” could be placed on the less sensitive
part of tissue surrounding the cornea. In 1887, he constructed
and fitted the first ever workable contact lenses based upon this
idea and these were made of heavy blown glass and covered the
entire eye surface with the empty space between the cornea and
glass filled with a sugar solution. As Fick’s lenses were
large and cumbersome, it was Muller who came up shortly with a
more manageable glass blown scleral lens.
Till the 1930’s, the above-mentioned scleral leses were
the only type of contact lenses available. Following this, plastic
scleral lenses were constructed for the first time with the invention
of polymethyl methacrylate – better known as Plexiglass.
William Feinbloom introduced the first American lenses where the
centre was made of glass covering the cornea with an outer band
of plastic covering the sclera. In 1945, the American Optometric
Association acknowledged the fitting of contact lenses to be an
important part of optometric practice.
In 1948, Kevin Tuohy started manufacturing contact lenses made
entirely of plastic but still covering the entire cornea. However,
in the later part of the same year, Butterfield modified Tuohy’s
design by manufacturing lenses, which had flatter curves and closely
corresponded to the corneal shape to sit better on the eyes.
Throughout the next two decades plastic corneal lenses were used,
which were much smaller and thinner and were placed on the cornea
rather than on the entire visible eye surface.
One of the major drawbacks of these PMMA lenses was that oxygen
could not pass through the lens to the cornea thereby potentially
resulting in serious side effects. Therefore, in the 1980’s
and 1990’s rigid oxygen permeable materials or polymers
were developed to counter this problem. These are hard contact
lenses and, though continuous improvements were made to make these
plastic lenses smaller and thinner, these were in general quite
uncomfortable for many users.
In 1960, Otto Wichterle’s experiments led to the path-breaking
discovery of the use of soft contact lenses made of a soft water
resistant plastic, which were more popular than the conventional
rigid lenses due to higher and more immediate comfort level. The
approval of the soflens material by the United States FDA came
through in 1971 and became available for commercial distribution
by Bausch and Lomb. Today about 90% of contact lenses sold in
the U.S are soft lenses.
In 1978, the first toric contact lens was also approved for commercial
distribution and silicone acryalate lenses (RGP) were marketed
in the next year. Over the next few years, extended wear soft
lenses, bifocal daily wear soft contact lenses, tinted RGP lenses,
extended wear RPG lenses, disposable soft contact lenses, planned
replacement lenses, disposable tinted contact lenses, daily disposable
lenses and first disposable lenses using ultra violet absorber
became available in the U.S for commercial distribution.
Finally in 1999 there was the distribution of silicone hydrogels
in the market. This coupled the advantages of high oxygen permeability
of silicone with the extreme comfort and clinical excellence of
hydrogels. These new lenses were originally only advised for overnight
use, but are now used for prolonged, multi day wear as well.
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