A nearsighted person wears contact lenses of refractive power −6.0 D. What is his far point?
A) 6.0 cm
B) −6.0 cm
C) 17 cm
D) −17 cm
E) −4.0 cm

Question

Quizplus · Accepted Answer

The far point of a nearsighted person is the distance at which the person can see objects clearly without accommodation. The refractive power of the lens needed to correct for this is equal in magnitude but opposite in sign to the person's refractive error. Therefore, the far point for this person is at a distance of 1 meter (100 cm) away from the eye, which is equal to the reciprocal of the refractive power in diopters. 
Far point = 1/(-6.0 D) = 16.7 cm ≈ 17 cm (rounded to nearest integer)

A Nearsighted Person Wears Contact Lenses of Refractive Power −6