Notations for testing at 4 meters (13 ft.)
Acuity range 20/125, 6/38 to 20/10, 6/3 equiv.)
Two smaller groups 5M to 2M for repetitive testing (20/25, 6/7.5 to 20/10, 6/3 equiv.)
Measures 23 X 35.5 cm (9 X 14 in.)
Can be wall-mounted
Practical for testing illiterate patients or testing in multiple languages
The Broken Ring or Landolt "C" test uses a single optotype placed in different positions; up, down, left, right, and 45 degree positions in between. Because there is only one optotype, patients simply have to gesture which position they see the optotype facing. Landolt "C" is helpful for testing illiterate patients that are not familiar with the Roman alphabet. Landolt "C" vision test are considered one of the best among alternative visual acuity tests.