Mark Hirschfeld Museum of Medical History - newsletter April 2021 - 2
Eyes have always fascinated humans. They
acquired metaphysical properties in antiquity,
from” The Eye of Horus” which was used by
ancient Egyptians to protect its wearer from evil,
to classical Greek mythology which related how
seeing the mythical gorgon’s face meant being
turned to stone. Vision is central to awareness
and consciousness. Modern neurophysiology
shows that the optical cortex has many
connections throughout the cerebral cortex
to explain the deep integration of vision into
emotions, memory, sensations and language.
Poor vision aects many humans, so it is
unsurprising to find that there have been
frequent attempts to improve human vision
across history. Whilst myopia or short
sightedness arises in childhood, presbyopia or
the diminishing ability to focus on objects at
close range aects us all in our fifth decade.
As the development of reading and writing in
the classical periods of both Asia and Europe
progressed, so to did vision related problems
and the need for corrective lenses. References
in texts are sparse which makes it dicult to
Glasses Apostle by Conrad von Soest from Bad Willungen
(wikimedia.org: Conrad von Soest)
Eyes and Glasses: Robert Craig, MHMH Volunteer
trace the development of spectacles. Claims
have been made around the world from China,
India, Africa, Arabia and southern Europe
though they are often found to be erroneous
or added later to ancient texts to establish
precedence. It is likely that spherical clear
quartz stones obtained magnification for
wealthy Egyptians in pharaonic times and
Emperor Nero was said to use an emerald to
see better in 60 CE. Protective eye covers were
recorded in China and Inuit used them to reduce
snow blindness. Widespread use of magnifying
tablets and stones by scribes and monks was
found in the twelfth century but the lack of
understanding of the behaviour of light on
reflective and translucent surfaces prevented
consistent progress. The Byzantine philosopher
and mathematician Ptolemy (100-170 CE)
studied optics and recognised magnification
was obtained by looking through transparent
spheres and spherical flasks filled with water
but he did not master the laws determining
reflection, refraction or chromatic aberration.
His written accounts travelled East and were
used by Islamic scholars, including Alhazen in
his Book of Optics ca. 1021. It seems likely that
the origins of modern spectacles are first to be
found in thirteenth century Italy. Records from
Venice (especially from Murano) suggest that
the glass makers’ skill allowed them to make
spheres accurately and magnifying convex
lenses quickly followed. Whether these were
made by blowing a hollow flask and using a
section of it as a lens or by cutting the lens
from a block or bisecting a solid sphere and
then grinding and polishing with serially finer
abrasives is unknown because the glass makers’
techniques were kept secret and were strongly
controlled by their guild to create a monopoly
for such valuable inventions. It is likely that
all these methods were used. Giordano of
Pisa wrote in 1306 of it being not 20 years
since eyeglasses had been made but the idea
of joining two lenses into a frame to make
spectacles took time. The earliest examples of
rivet spectacles were found in Celle in Germany
dating from 1400 and the first spectacle shop
opened in Strasbourg in 1466. Trade in lenses