My eye doctor gave me a new contact lens to compare to my old prescription. So I decided I wanted a good eye chart to compare the new lenses.
A bit of research led me to believe the Landolt C eye chart would be the best for me.
From Wikipedia:
The Landolt C consists of a ring that has a gap, thus looking similar to the letter C. The gap can be at various positions (usually left, right, bottom, top and the 45° positions in between) and the task of the tested person is to decide on which side the gap is. The size of the C and its gap are reduced until the subject makes a specified rate of errors. The minimum perceivable angle of the gap is taken as measure of the visual acuity. It is generally practiced in the laboratory.
The stroke width is 1⁄5 of the diameter, and the gap width is the same. This is identical to the letter C from a Snellen chart. The Landolt C is the standard optotype for acuity measurement in most European countries. It was standardized, together with measurement procedures, by the German DIN, as DIN 58220 (now EN ISO 8596).
Unfortunately, I couldn't easily find one of these sized for viewing at 10 feet. So I made one!
I can't guarantee this is made correctly, but I think it is right.
