home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
Contact Lens Series
/
Contact Lens Series Volume 1.iso
/
mac
/
Contact Lens Series V1(MAC)
/
Introduc.DIr
/
00030_Field_30.txt
< prev
next >
Wrap
Text File
|
1997-10-29
|
673b
|
20 lines
HYDROGEL (SOFT) LENSES
In the 1950ΓÇÖs Otto Wichterle and
D. Lim of Czechoslovakia developed
a hydrogel material and made contact
lenses from it. This material is hard
in the dehydrated state but soft and
flexible in the hydrated (wet) state.
The lenses were made of
hydroxyethylmethacrylate (HEMA).
This material as well as numerous
variations of it are used today.
These early lenses often did not give good vision and had some problems including causing corneal edema, deposits built up on the lenses and they were fragile.
Hydrogel lenses have been greatly refined and are now the majority of lenses fitted.