Eye test explained!
The eye test (Snellen's) consists of a series of letters of varying sizes, so that the top letter is visible to the "normal" eye at 60m, and the subsequent lines at 36,24,18,12,96 and 5m respectively.
Visual acuity (the thing you are measuring) is recorded as
d/D
where d is the distance at which the letters are read (usually 6m), and D is the distance at which they should be read. (6m usually).
The normal person can usually read the 7th line, ie 6/6.
It used to be measured in feet, hence the phrase 20/20 vision.
Hope it clarifies the situation.
Any tips on landing cessna's.