Measures of Visual Acuity

Visual acuity generally is measured using eye charts that assess an individual’s ability to see letters, numbers or other shapes at a distance.  The most common eye chart used in doctors’ offices to measure distance visual acuity is the Snellen chart, a series of letters or letters and numbers with the largest at the top.  The Rosenbaum PocketVision Screener is used to measure near visual acuity.

Distance Visual Acuity

Use the arrow keys to see the difference in distance visual acuity.
(For illustration only)

Snellen Chart

20/20

Patients see at 20 ft. what a person with normal vision sees at 20 ft.

20/25


Patients see at 20 ft. what a person with normal vision sees at 25 ft.

20/30


Patients see at 20 ft. what a person with normal vision sees at 30 ft.

20/40


Patients see at 20 ft. what a person with normal vision sees at 40 ft.

Near Visual Acuity

Use the arrow keys to see the difference in near visual acuity.
(For illustration only)

Rosenbaum PocketVision Screener

J1+


Patients can read 3pt font size (for example, stock quotes in the newspaper)

J1


Patients can read 4pt font size (for example, stock quotes in the newspaper)

J2


Patients can read 5pt font size (for example, the normal type on a classified ad)

J3


Patients can read 6pt font size (for example, the normal newspaper size)

1 National Eye Institute, National Institutes of Health.