I'm trying to measure the amount of prescribed prism in my lenses. I'm not second guessing the lenses ... I'm sure they have in them what they should ... just interested to know how to do it myself.
This is what I have done so far ... found optical centre by determining the part of the lense that has no induced prism and dotted. Now measure the distance between the dots and this tells me how much the prism has decentred the OCs. There is a difference of about 8mm between this measurement and my PD. Now I know this does not mean there is 8d prescribed prism because there is also lots of power correction in the lenses and this must somehow be incorporated in the calculations ... and perhaps prentice's rule might come into it somewhere ...
so what additional numbers do I throw into the mix to determine the actual amount of prescribed prism
Any help would be great :bbg:
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