How do I measure prism thinning?
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How do I measure prism thinning?
This thread should help. Also every optician should read the second thread about progressives and where the why it is done is discussed at the very end.
It is as a rule of thumb about 2/3 of the add power base down on both lenses on plus lenses.
https://www.optiboard.com/forums/showthread.php/28014-prism-thinning-an-invisible?highlight=measure+prism+thinning
http://64.50.176.246/cecourse.php?ur...essive_lenses/