Change in fluorescence intensity after application of KCl. A. Change in percentage of fluorescing iris area over a 450 s period (one measurement per 5 s) averaged for 25 s time intervals for 8 eyes from 8 different individuals. KCl was added at time point 0 s. B. Change in iris fluorescence brightness over time in 6 eyes from 3 individuals expressed as total photon radiance (photons.s-1.sr-1.m-2) in the emission range 550–700 nm at each time point. Colours indicate individuals.