In a previous communication1 it was determined that for the average normal person there exists a zone between 50 and 60 degrees on the horizontal temporal meridian outside of which there is no perception for a rapid flash of light or a speed of approximately one twenty-five thousandth of a second. As was stated at that time, such determinations were found during the attempt to study a method for investigating the chronaxia of the optic nerve.
Perimetry has a long history dating from the time of Ptolemy;2 its scientific basis was laid down by von Graefe3 and Förster4 and is further elaborated in the present-day texts of Peter5 and Traquair.6 Many are the contributions to perimetry, but as yet no one has made use of the flash of a light as a test target. Presentation of this new method was received