Prescription AnalysisQuestion 54 of 100
Reading an Rx that lists 'BO' after a prism value indicates the base is oriented how?
a.Base up
b.Base down
c.Base in
d.Base out
Explanation
BO stands for base out, meaning the thick base of the prism points toward the ear (temporal side). BI means base in (toward the nose), BU base up, and BD base down.
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