Can someone please help me with this. I've found different answers as to when prism compounds or cancels when it comes to base in and base out prism. According to the "Ultimate ABO Study Guide" by opticianworks, BI/BO - cancels and BI/BI & BO/BO - compound. However when I took the practice test on opticianworks the answer to this question contradicts that.
35. Which of these prism combinations compounds or adds together?
· Base In/Base In
· Base Down/Base Down
· Base Up/Base Up
· Base In/Base Out
And for this question, why are we canceling them when its BD/BU? Wouldn't they compound? I got the right eye as 2.8 BD and the left as 1.5 BU.
38.
· Right eye Rx is -5.75 -1.25 X 180
· Left eye Rx is +5.75 -2.00 X 180
· Customer sat on their glasses and decided to wear them until they could come in.
· Each lens is sitting 4mm high
· How much prism and in what direction did they experience until they saw you?
·1.3 BD R
·4.3 BD R
4.3 BU L
·2.8 BD R
1.5 BU L
·5.1 BU R
5.1 BD L
I'm taking my ABO on November 11th and this is driving me nuts! Thank you guys.
Bookmarks