 |
|
Reading glasses first appeared in Italy in the 1260's to help the
elderly to read, these were for those whose vision had become blurred due to
age. Their popularity was instant, and paintings from the time began to depict
wearers in both religious and scholarly settings.
|
However the initial design had a enormous problem: with only the bare basics of
lenses and a nose bridge, there was no easy way to keep the darn things from
slipping down the nose. They had to hold them in place, which limited their
use. The Spaniards tried connecting them to ribbons looped around the ears, but
that never worked.
|
In 1730-nearly 500 years after they were first introduced-that a London
optician named Edward Scarlett finally devised the rigid sidepieces that rest
at top of the ears. The perfection spread rapidly, and is still in use today.
|
Eyeglasses
consist of a pair of lenses mounted in a frame to hold them in position before
the eyes. Roger Bacon probably invented the first device of this kind in the
13th cent. Although similar devices have been existed in ancient times in China
and in the Mediterranean civilizations. Early forms were unsophisticated and
awkward and were not improved till the 18th century, when the grinding of
lenses started based upon the principles of refraction light.
|
Eyeglasses
frames are typically made of either metal frames or a type of plastic frames
called cellulose acetate. Cellulose acetate is derived from cotton and is
flexible and strong. It is produced in long narrow sheets that are slightly
wider than eyeglass frames.
|
Lenses were made of plain or rock crystal glass or plastic to suit the defect
of the eyes.
|
For
making the rays of light diverge concave glass are used for nearsightedness.
|
For making the light rays converge convex lenses are used for farsightedness.
|
Cylindrical lenses cure astigmatism.
|
Benjamin
Franklin had developed the
bifocal
reading glasses in the 1780's, because he got tired of changing to
reading glasses whenever he opened a book, which was often. He had his optician
cut the
lenses
in two so he just had to look up and down instead of switching glasses. This is
still in use today.
|
A
contact lens
is shaped to fit the eye and is worn under the eyelid. Incorrect
eyeglasses may do harm, and lenses should be prescribed by an
ophthalmologist
or
optometrist
and fitted by a skilled
optician.
Eyeglasses to protect the eyes from glare are made of
tints
or polarized glass. The Eskimo make and use wooden eyeglasses that have only
narrow slits for eyepieces to protect the eyes from glare reflected by ice and
snow.
|
It is possible to assume, that the absence of such means significantly
prevented the development of sciences and the art of thin crafts in the
previous centuries.
|
| Today
we have a wide variety of eye care products ranging form rimless frames, semi
rimless frames, plastic frames, metal frames, titanium frames with
bifocals
lens, progressive lens with different tints, anti reflective coating, anti
scratch coating, photo chromic lens, ultra violent
etc. You can find all the above-mentioned products at BMG without going
anywhere to your doorstep. |
|
 |