A population study is proposed to determine the association between blood pressure or blood pressure change and the presence of glaucomatous-like visual field defects. Persons in the study populations found to have visual field defects, as carefully defined, will be referred to a consulting opthalmologist for definite diagnosis. The study population will be all those persons in the current on-going study of hypertension therapy (Hypertension Detection and Followup Program, principal investigator Dr. Albert Oberman - University of Alabama in Birmingham), sponsored by the National Heart and Lung Institute. This study involves three groups totaling approximately 1,000 persons drawn from a random sample of Birmingham. The three groups include one with systemic hypertension and usual treatment and one with systemic hypertension and intensive treatment. These groups are carefully defined and have been intensively followed for four years. The proposed study will occur during the fifth year of this ongoing study. The availability of this unique population allows for the investigation of the theoretical prediction, based on the perfusion pressure theory, that lowering blood pressure may cause visual field defects. Such theory would predict that the group with the greatest reduction in blood pressure, the intensively treated group, would have the greatest number of visual field defects. If the association between blood pressure reduction and visual field defects is significant it would have serious implications for the current mode of therapy for systemic hypertension. The proposed study would provide important new clinical evidence of this association.