Figure 1
From: The effect of different criteria on the number of patients blind from open-angle glaucoma
Calculation of the diameter of the remaining visual field. The central visual field is indicated by the pseudoisopter (red line). The distance is 6° between each test point location and 3° between test points and the pseudoisopter. The pseudoisopter is used to calculate the widest diameter of the remaining central visual field. This field is constricted to 18° around the point of fixation.