How is near vision measured?
JAN 04, 2016
How is near vision measured? What does it mean to have a visual acuity of 20/50 but a near vision acuity of 20/200 sc (without correction)? Which is a more accurate measure of the person's vision? Can a near vision acuity be used to determine if a person is legally blind?
Near vision is traditionally measured with a hand-held card similar to a vision chart on a wall. Normally only distance vision is employed to assess legal vision.
20/50 vision indicates that vision is reduced more than 50 percent from normal 20/20 or even 20/15.
Importantly, in an eye with normal distance vision, near vision requires additional focusing called "accommodation." After age 40 to 50, additional optical assistance with reading glasses or bifocals is usually required for normal near vision. If your uncorrected vision is only 20/50, you should be evaluated by an ophthalmologist, particularly if you drive.