Answer to test prep question wrong?

[JBW]

Hello All, I'm going crazzy with this question. No one I work with can explain why the test prep answer is correct. I keep getting a different answer. What is the correct answer & why. Thanks!

Calculate the amount of prism induced in the following patient situation:

Patient PD 58mm
Optical centers 62 mm
Lens power -1.50 -1.50 x 180

[optical24/7]

Prentice Rule: cm x power

figure power in the meridian ( direction in question, horizontal 180, or vertical 90). Test question is horizontal. At 180 your power is -1.50. 62 OC vs 58 patients PD = 4mm difference. .4 X 1.50 = .60^ . Now what direction? What if the Rx is OU? How much each eye?

[JBW]

THANKS for confirming my sanity.

The test prep software and all my co-workers say the answer is 0.30D OU BI.

Whereas, I was saying that it was 0.30D BI from each eye, making the total prism induced 0.60D OU BI.

[chrisvanvliet]

In a minus lens, if the OC is OUT, the base is IN.