DPE Calculations

**optimite** · 05-08-2014, 08:17 AM

What is the DPE in the vertical and horizontal meridians when a person wearing the following rx reads through points 8mm below and 2mm in from their distance OC

Re: +2.00/-1.00 x 90
Le: +4.00/-1.25 x 90

**MakeOptics** · 05-08-2014, 12:47 PM

Originally Posted by optimite

What is the DPE in the vertical and horizontal meridians when a person wearing the following rx reads through points 8mm below and 2mm in from their distance OC

Re: +2.00/-1.00 x 90
Le: +4.00/-1.25 x 90

Assuming they are not looking for the more complex version of prentices rule incorporating torsion of the cylinder, you can use the power in the meridians questioned and the prentice formula to calculate.

RE

Power@090 = +2.00
Power@180 = +1.00

Vertical Prism = +2.00 x 0.8 = 1.6
Horizontal Prism = +1.00 x 0.2 = 0.2

LE

Power@090 = +4.00
Power@180 = +2.75

Vertical Prism = +4.00 x 0.8 = 3.2
Horizontal Prism = +2.75 x 0.2 = 0.55

Now the difference can be computed I'll leave that up to you. Try working the problem out and then asking a question so you don't miss out on your education and you can tell where you are making your mistakes.