topic 5C physical characteristics of ophthalmic lenses (-ve +ve cyl transposition) Flashcards
1
Q
what kind of prescription is usually given at end of eye sight test?
A
Usually, the prescription that is provided at the end of a sight test is written in its minus cylinder transposition
2
Q
how to transpose from +ve cyl format to -ve cyl format?
A
Sph: sum of sph + cyl
Cyl: old cyl change of sign
Axis: change axis by 90
3
Q
what direction does the axis follow?
A
anti-clockwise
180
4
Q
what is a power meridian?
A
the meridian with higher power
5
Q
what is a axis meridian?
A
meridian with lower power
