A computer-controlled system for measuring dark adaptation and other psychophysical functions

Abstract

• Background: Psychophysical thresholds, including dark-adaptation functions and increment threshold sensitivities, are useful for the early detection and diagnosis of visual pathologies. However, few instruments have been designed or adapted for their routine clinical measurement. • Methods: Here we describe an instrument prototype designed to meet this need, which we refer to as the PULS (Programmier-barer Universeller Licht-Stimulator). The instrument is computer-controlled and fully automated. It allows direct control over target location, luminance, size, duration and temporal profile and over background luminance and spectral composition. It also incorporates an efficient and statistically rigorous strategy for determining threshold. • Results: We present examples of psychophysical functions — dark-adaptation curves, increment threshold sensitivities, estimates of temporal summation in the dark and during the time course of dark adaptation — which have been measured by the PULS prototype in normal observers and clinical patients. • Conclusions: The PULS instrument provides an automatic and efficient means of measuring dark adaptation and other psychophysical functions. It determines threshold by a more rigorous and faster method than is conventionally employed in clinical adaptometry.