Position Index for a glare source located below the line of vision

Abstract

To measure the difference between sensitivity to glare from a source above the line of vision and that from a source below the line of vision, two subjective experiments were conducted using the adjustment method and the constant method respectively. The sensitivity to the glare caused by a source located below the line of vision was greater than the sensitivity to glare caused by a source located above the line of vision. This tendency was seen especially in elderly subjects. For vertical displacement the difference in sensitivity between sources above and below the line of vision increased with increasing angular distance between the line of vision and glare source.