Hello, I am very new to Optiborad. I am taking the ABO exam on this November and I studying with ABO study guide by Gary McArrel, but there was a difficult question that I really don'y understand. The question was " The lab used prism thinning to improve the cosmetics of a pair of progressive addition lenses. The lab ticket calls for OD 1 ^ base up and OS 1 ^ BD. When you are verifying the finished glasses at the prism reference point which of the following prism combination would be? and the answer from this book is OD 1 ^ BD / OS 3^ BD.
I do not know how he got 3 base down on OS. This question is driving me crazy!!!
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