13 - Spectacle Magnification Flashcards
What does spectacle magnification compare?
Compares the size of the image seen by the person when wearing glasses with the size of the image see when they are not wearing glasses
What is spectacle magnification?
magnification change brought about by a single spectacle lens
What are the 2 components of spectacle magnification?
Shape Factor - is an afocal (telescope-like) component
Power Factor - power component
What are the 3 things included in the shape factor part of spec mag?
Index
Thickness
Front curve
What are the 2 things included in the power factor part of spec mag?
Wearing distance from the back vertex of the lens to the entrance of the pupil of the eye
Back vertex lens power
Practice examples of finding Spectacle Magnification
What is the distance from the cornea to the opening of the pupil?
3mm
What does a 1 or 0 in front of the final number mean?
1=magnification
0=minification
