Snel·len chart (snělən)
n.
A chart for testing visual acuity, usually consisting of letters, numbers, or pictures printed in lines of decreasing size which a patient is asked to read or identify at a fixed distance.

[TahlilGaran] American Dictionary ▲

snellen chart
[After HermanSnellen (1834-1908), Dutch ophthalmologist.]

[TahlilGaran] American Dictionary ▲