Optics Flashcards
1
Q
What is image jump?
A
Amount of (additional) prism induced at the bifocal line due to the add.
- calculation only requires seg style and add amount
- always BD
OC and FT edge = 5mm
Executive/Franklin and R-segs are 7mm
2
Q
What must ALL lenses be able to withstand?
A
Impact of a 5/8 diameter steel ball dropped from 50 inches.
3
Q
What must SAFETY GLASSES be able to withstand?
A
Impact of 1” diameter ball for testing from 50 inches.
4
Q
What is the marking on a safety lens?
A
Z87
5
Q
Prescription lenses must have minimum thickness of ____ except for plus lenses with >=3.00D?
A
3mm
6
Q
How to increase spectacle magnification?
A
- steepen base curve
- increase center thickness
- lens power (increase power of plus, decrease in minus)
- vertex (increase in plus, decrease in minus)
7
Q
Field of view for plus lens increases when..?
A
- power decreases
- distance decreases
Higher the power, smaller the field of view.
