The primary treatment trial: changes in the visual field analysis by computer-assisted perimetry

Computer-assisted perimetry was performed 6-monthly on patients entered into the Primary Treatment Trial using the 30-2 program. Those patients with a minimum of five visual fields had pointwise linear regression analysis (Progressor) carried out. Two consecutive slopes significant at the 0.05 level were taken as evidence for change, either improvement or worsening. Forty-eight patients in the surgery group, 40 in the medical group and 20 in the laser group were suitable for analysis. A comparison of the eyes showing 'improvement' or 'worsening' in the surgery and medicine groups showed no difference between them. This lack occurred despite a significant difference in intraocular pressure between the two groups. The reasons for this lack of difference are discussed.