what is a transposition ?
The change of power prescription from one form to another form is called as transposition. in simple word the change of power prescription plus form to minus form.
Type of transposition ?
transposition has to types...
1. simple transposition
2. Toric transposition
what are rules of transposition ?
Simple transposition has three rules...
1. addition of spherical power plus cylindrical power
2. change the sign of cylindrical power
3. change the axis by 90 , if axis less than 90 we need to add a 90, or if Axis more than 90 we substract the 90.
Why need of transposition ?
the lens inventory is not available at a market so that the transposition is needed for to given same power in another form.
transposition is optometry and ophthalmic calculation to change the power prescription from one form to another form, it is a very simple calculation and it should be handy for Optometrist, opticians and ophthalmologist
lens transposition of power prescription of spectacle lenses | lens prescription explanation
https://youtu.be/HVWN3SmTSBY