Abstract
Glare may be caused by two fundamentally different effects; the veiling and the adaptive effect. A binocular method is described with allows of measuring the adaptive effect. When a glaring light source is placed somewhere in the field of view the sensitivity of the fovea drops to a considerably lower level within one tenth of a second (a-adaptation). After short times of exposure to the glare source the sensitivity rises quickly, after longer times it rises more slowly towards its original value (adaptation).