Unit 1 Flashcards
(49 cards)
Types of advanced contact lenses
-high astigmatism toric
-high powered plus or minus
-multifocal
-extended wear
-cosmetic tint
-costume, theatrical and prosthetic
-RGP, sclera, hybrid
-myopia control and ortho k
when were glass contact lenses made and how they feel and who created it?
- late 1880s
-Adolf gaston eugene fick
-low comfort and high rates of hypoxia due to lack of oxygen
What did Dr Feinbloom introduce
Patented plastic lenses in 1936
PMMA introduced later that year (greater comfort but still had issues w/ hypoxis)
PMMA (polymethyl methacrylate) when were they made and by who?
-designed in 1948 by kevin tuohy
-New plastics after the war
-Plexiglass
-Single curve design
-11.00mm diameter
Change to a bicurve in the 1950s
PMMA corneal lens ADVANTAGES
Durable
Good wettability
Good optical clarity
Can be sterilized
PMMA disadvantages
low oxygen transmission
When was silicone rubber developed?
1965
Advantages of silicone rubber
1000x more oxygen transmission than PMMA
can be moulded
disadvantage of Silicone rubber
hydrophobic
elastictiy can grab cornea
disrupts tear layer
What is silicone rubber used for
babies with congenital cataracts
When was RGP lenses developed
1974
RGP material : Silicone acrylate when was in developed
1970s
RGP lens materials?
-Silicone acrylate
-Siloxy-methacrylate monomsers
-Flourocarobs
Menicon O2
first RGP lens
Launnched in Japan in 1979
Polycon lens
“hard” lens launched in 1980 in USA
-Not an RGP lens because it was not oxygen permeable
excel 02
rgp with improved wetability in britian in 1980s
boston II matieral
-available in 1982 in USA
-future generations still used today
tinted RGPS
available in 1983 - only handling tint - did not change eye colour
extended wear RGPS
menicon EX
menicon EX
launched in 1986 in Japan
5x more oxygen permeable than menicon O2
Flurosilicates
increased oxygen permeability and strength in 1990s
menicon super EX
bicurve
2 radius of curvature on back side of lens
-can be used with smaller diameter lenses
-central radius and flatter peripheral curve
tricurve
3 radius of curvatures
-most commonly used design
-central radius and 2 or more periphral curves
tetracurve
4 radius of curvature on the back of the lens
-can be used with larger diameter lenses