Question
Question: A presbyopic patient has near point as 30 cm and far point as 40 cm. The dioptric power for the corr...
A presbyopic patient has near point as 30 cm and far point as 40 cm. The dioptric power for the corrective lens for seeing distant objects is
A
40 D
B
4 D
C
– 2.5 D
D
0.25 D
Answer
– 2.5 D
Explanation
Solution
In this case, for seeing distant objects the far point is 40 cm. Hence the required focal length is
f=−d(distance of far point) = – 40 cm
Power 