Using automated perimetry the distribution of visual field loss in 40 chronic open angle glaucoma eyes (40 patients) was found to be predominantly in the nasal, supranasal, and superotemporal regions. The rate of change of visual field threshold values in seven regions of the field was measured by trend analysis over 44.9 +/- 17.9 months. Seventeen eyes had a significant rate of field loss in one or more regions of the field with the remaining eyes either showing improvement or stability. Seven of the 17 eyes with significant regional field loss had stable overall fields. The greatest rate of field loss occurred in the temporal and superotemporal regions. The correlation between the mean threshold value of the initial field test and the rate of change of field over time was significant in the temporal region and of borderline significance in the superotemporal region. The relationship was such that the greater the initial threshold value, the greater the subsequent rate of field loss.