Lens Evolution Flashcards
Through which years were the First pair of glasses made and worn by scholars?
1268-1289
The first glasses made were made from what materials?
Wood, leather and glass
In the 1400’s, what invention prompted the need for eyewear, and which types were used?
The invention of the printing press. Monocles and lorgnettes are used.
In which year did the first eyewear that goes over the ears get developed and who was it’s inventor?
1700 by Benjamin Franklin.
Between which years did eyewear become more popular among scholars and the wealthy?
1800’s-1900’s
When did eyewear become more mainstream?
the 1900’s
When did we transition from only using glass for lenses to using other materials?
The mid 1950’s
Why do we not use Periscopic Lenses much today?
While they are cosmetically great, they are visually not a great option as they compromise vision and induce cyl the higher the Spherical Rx
Chart of Astigmatic error with Periscopic lenses
Sphere Power Cyl Induced
-4.00 +0.81
-2.00 +0.55
+2.00 -0.94
+4.00 -1.60
How much Base Curve does a Periscopic Plus lens have?
-1.25 back BC
How much Base Curve does a Periscopic Minus lens have?
+1.25 front BC
What lens type was used after Periscopic lenses?
Meniscus Lenses
What are Meniscus Lenses?
crescent shaped lenses where one side is concave and one side is convex
What is the advantage of Meniscus lenses over the previous lens type?
Astigmatic error was reduced
Chart of Astigmatic error with Meniscus Lenses?
Sphere Power Cyl Induced
-4.00 +0.03
-2.00 +0.05
+2.00 -0.05
+4.00 -0.09
