Estimation of visual acuity
Dep. of Physiology, Fac. of Medicine, ML), 2016 © Zuzana Nováková
Snellen's optotype
Landolt's circles
Pfluger's hooks
XU A
H T YO
1B
V U A X T
i j
H A Y O U X
YUXTHAOV
E
XOATVHUY
c
o c
coo
o o o o
o o c o c
c  o c o c o
o  o o o  o c o
m a
LUEm
E Bium
m e m uj 3
a ljj 3 e m w
Physiological base: 1 minute - is the limit of two-point discrimination in a normal eye
Visus is the ratio of the distance from which the tested person could read letters of a given size, i.e. here 5 m,
to the distance from which a normal eye can read them which is the number found at the corresponding line of the table.
The fraction is not evaluated, i.e. one writes:
V = 5/5 (normal eye)
V = 5/10 (reduced acuity)