Visual Field Assessment

Visual fields are considered unreliable and repeated when fixation losses are at least 25%, false negatives at least 30%, or false positives at least 30%. Mean deviation represents the average difference between age-corrected normal sensitivity and measured threshold sensitivity across test locations. The study eye is always tested first, followed by the fellow eye, and measurements are then repeated in the same order. The primary endpoint is the difference between groups in absolute change in Humphrey visual field mean deviation at 18 months. Humphrey 24-2 standard static threshold perimetry is used because it provides reliable glaucoma measurements.