Threshold perimetry in tilted disc syndrome. Twelve consecutive patients (17 eyes) with tilted disc syndrome underwent quantified visual field examination with the G1 Octopus program (Interzeag AG, Schlieren, Switzerland). Visual fields were abnormal in all cases. Although field loss was more pronounced in the superotemporal quadrant (P less than .001), it also involved the other three quadrants, thus demonstrating that optic nerve hypoplasia in tilted disc syndrome is apparently not entirely sectorial. Linear regression analysis showed that an increase in mean defect correlated with increase in myopic refractive error (P less than .05). However, the increase in myopic refractive error was found to be related to a decrease in corrected loss variance (P less than .05), indicating that in tilted discs with higher myopia, field loss is more homogeneous. With this series of patients, short-term fluctuation was within normal ranges in all visual fields, showing that this may be an additional clue for differential diagnosis from acquired disorders. 