L2 Impact Resistant Lenses Flashcards
1
Q
What are the methods of increasing impact resistance for glass lenses (3)
A
Lamination, thermal toughening, chemical treatment
2
Q
State the lens materials from lowest to highest impact resistance
A
Untreated glass, thermally toughened glass, chemically treated glass, CR 39 (n=1.49), hi-index plastic, polycarbonate/trivex)
3
Q
How to increase IR for plastic lenses (naturally impact resistant)
A
- uncoated
- increase centre thickness for minus lens
- increase edge thickness for plus lens
4
Q
Who needs impact resistant lens (dress eyewear)
A
- monocular
- children
- elderly (esp with bad legs)
- pseudophakes, aphakes and after lasik
5
Q
Who needs impact resistant lens (safety eyewear)
A
- working in dangerous industries with flying object hazards
- doing dangerous hobbies: carpentry, squash
6
Q
how to determine proper safety frame
A
Z87.1 marking
