Induced unwanted optical effect when line of sight isn't perpendicular

Hello,

How can I calculate prizmatic and induced unwanted power effect if we have next situation:
line of sight isn't perpendicular in respect to the back side of lens, it is about 76 deg. and power of lens is +1.00 D. What kind of calculation is needed to find the answer?

Thanks in advance,
Wlada

Induced unwanted optical effect when line of sight isn't perpendicular