Differential light threshold in automated static perimetry. Factors influencing short-term fluctuation.

The scatter of the differential light threshold observed during a single visual field test is called the short-term fluctuation. A number of factors that may influence the magnitude of the short-term fluctuation were studied. The main factor was the level of the differential light sensitivity itself, followed by the rate of false responses in the catch trials. The pupil size was only notable in patients with glaucoma, while age as well as the mean reaction time did not appear to be notable. The short-term fluctuation is not dependent on the location in the visual field up to 27 degrees of eccentricity degrees tested in normal subjects and patients suspected of having glaucoma, but there is a slight tendency in patients with glaucoma for a larger short-term fluctuation in the upper half of the visual field.