(Frequently Tested) with Verified
Answers Graded A+
What is the prism created by a +5.00 diopter lens decentered 2 mm? - Answer: Use Prentice's
Rule:
Prism (Δ)=d×P/ 10
Where:
d=2d=2 mm
P=+5.00P=+5.00 D
Calculation:
Prism (Δ)=2×5/ 10=1 diopter of prism
Answer: 1 diopter of prism
Why does a negative lens decentered by 8 mm create a base-in prism effect? - Answer: -
Negative lenses are thicker at the edges and thinner in the center.
- When the lens is decentered inward (towards the nose), the thicker edge moves closer to the
center of the frame.
- Light bends toward the thicker edge, which creates a base-in prism effect, as the base of the
prism is now pointing towards the nose.
This causes objects to appear shifted inward.