Hello,
Contact lenses are a thin plastic or glass lens that is fitted over the cornea of the eye to correct various visions. The optical principle underlying the contact lens can be understood by investigating the lens in optics.You can find some information about lenses in
http://www.answers.com/topic/lens-1
Moreover, you can view these sites as well:
http://www.answers.com/topic/contact-lens?method=22
http://www.sciencedirect.com/science/journal/13670484
Lastly I should say that you want to learn about structure of material of the contact lens. You should look at several reference books:
-Contact Lens Optics & Lens Design, 3rd edition, By William A. Douthwaite, ISBN 0750688793 Butterworth Heinemann, Published December 2005
-Contact Lens Practice, By Nathan Efron, ISBN 075064690X Butterworth Heinemann, Published January 2002.
-The Contact Lens Manual, 3rd edition A Practical Guide to Fitting By Andrew Gasson, and Judith Morris, ISBN 0750655488 Butterworth Heinemann Published July 2003.
Best wishes,
Try the links in the MadSci Library for more information on Physics.