L3 Power and Lenses

Question 1

Lensmakers Equation

Answer 1

F = (n-1)(1/r1 - 1/r2)

for overall power of the lens

Question 2

Fundamental Paraxial Equation

Answer 2

L’=L+F

Question 3

Effective Power of the Lens

Answer 3

In distance vision:
The back vertex distance in mm is the distance bet the back vertex of the lens and the cornea and it affects the power of the lens (BVD)
If you increase the distance from the lens to the eye then the lens becomes more positive - so you have to make the prescribed lens more negative

Question 4

Does thickness matter?

Answer 4

When light travels through a medium other than air, so real thickness of the material (t) can be replaced by an equivalent thickness of air (d)
d=t/n