The SD of static visual threshold ranges from 0.12 log units near fixation to 0.41 log units 30 degrees from fixation. Among 60 points tested, most persons have at least one point that tests 0.5 log units less sensitive than the adjacent points, simulating a scotoma 0.5 log units deep. With automated kinetic perimetry, the SD of isopter position is 2.6 degrees to 5.5 degrees, with the greatest variation appearing in the temporal field where the slope is flatter and the isopters are more peripheral. More than 10% of the points show an inward deviation of 5 degrees or more compared with their neighboring points. Retesting of the deviant points is required to distinguish an artifact caused by variable responsiveness from true localized defects. Judgments about progression also require that the accuracy of the isopter position or threshold determination be taken into account.