IT IS GENERALLY admitted that a comparative study of the visual field is the most important index of the progress of the disease in a given case of glaucoma. Since there is considerable variation in the evolution of the field defects in individual cases, it was deemed advisable to undertake a survey and classification of a large sample of unselected cases. The material for the present study consists of approximately 2,000 visual fields representing 350 patients with glaucoma from private practice.1 By appropriate grouping of these fields, it was found possible to follow the evolution of the various components of the field defect. An attempt was then made to formulate a hypothesis which would adequately explain the pathogenesis of the elements of the glaucoma field. These field studies have been carried out by a uniform method over the past fourteen years. The technic will be described later. Figure 1