Estimation of visual acuity
Dep. of Physiology, Fac. of Medicine, MU, 2016 © Zuzana Nováková


Snellen´s optotype
Landolt´s circles
Pflüger´s hooks

5´
1´
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)