| ¡¡People¡¯s life
style and occupation was restricted by sight before
glasses had been invented. For example, hunter
must have but handicraftsman who use myopia power
usually have to retired after age of 45-50 because
of their short sight. The early lens is plane-concave
lens. It¡¯s called ¡°lens¡± because it looks like
plane-concave. The early magnifying glass can
be traced back to 10th century. And the increase
of demand for well sight along with spread of
atomization and invention of printing promoting
the development of glasses
¡¡13th century, people began to use the lens of
glass to remedy sight, The melted glass was poured
into a special mold to make into glasses. The
first record of eye sight correcting is done by
Roger Bacon. ¡°The letters become bigger and clearer
when you look through a crystal ball¡±, written
by him.
¡¡Since Johan Gutenberg invented typewriter, with
the rapid development of print, the demand of
sight-remedy reached a new top. And mainly are
convex lens for remedying presbyopia at that time.
The concave lens is found soon to help myopia
patient to see the objects in further distance.
From that time people started to classify the
lens by diopter but not age. The first glasses
was two lens tied by a cord in front of eyes.
¡¡In 18th century, Chinese invited
the ¡°ErCheng
Britain optometrist Edward Scanlett made primary
glasses frame,became the embryo of update glasses.
¡¡1784s , In 1784, Benjamin Franklin made the first
pair of bifocal lens by two sets of lens.
¡¡In 19th century, that¡¯s
the important period for the development of lens
and glasses.
¡¡In 1827s, Fuller invited cylindrical lens for
remedy astigmatism.
¡¡In 1860s, Snellen invited standard eye chart.
¡¡In 1837s, Lsaac Schnaitman perfected demo bifocal
lens.
¡¡In 1899s, John Borisch invited amalgamation bifocal
lens, and named it¡°contact bifocal¡±.
¡¡¡¡Today, all lenses have a standard base. It is
appeared in 1890s. The producers of lens never
stop to update their products to meet the request
of the demand. They volume- produce of tint glasses
(for example: sunglass) start from earlier 20th
century, this kinds of lenses is to perfect sight
and reduce the harm of infrared ray
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