Disclosing disease mechanisms with a spatio-temporal summation paradigm

Abstract

Background: We develop the logic for a stimulus that can evaluate cone-dependent spatial summation and detail the modelling and interpretation of thresholds obtained with this stimulus. Methods: Fifteen observers participated, including two young normals tested extensively in control experiments, and a clinical trial based on four observers with age-related macular degeneration (AMD), four age-similar controls and five young observers. Monocular spatial summation functions were measured with contrast-modulated Gabor targets that approximated the optimal visual contrast detector. Thresholds were returned from a yes/no adaptive psychophysical algorithm. By fine titration along the size domain ..