SENSITIVE METHODS FOR THE DETECTION OF BJERRUM AND OTHER SCOTOMAS

Abstract

In a former paper two of the present writers described methods for increasing the diagnostic sensitivity of perimetry with the form field stimulus. It was pointed out that the methods described should be especially effective and feasible in that branch of field study that is commonly called scotometry. It is our purpose in the present paper to show with what success the methods may be used in the early detection of the Bjerrum and other scotomas. In the practice of scotometry with the form field stimulus, the means for increasing sensitivity are comparatively obvious. In order to pick up faint or incipient scotomas, it is necessary only to decrease by sufficient amount the visibility of the stimulus. The amount of increase in sensitivity that can be secured in this way clearly is limited only by the threshold of visibility. The three most important factors in the visibility of an