Will measure time to several hours. Stimulus is second flash. Intensity is adjustable over a 3 log unit range in 0.1 log unit steps. Whole-field Scotopic Sensitivity Implements modified test of Glovinsky et al. No need for steady fixation or refractive correction.
Results are relatively unaffected by mild cataract.
Stimulus is 4 seconds of 1 Hz sinewave flicker. Intensity is adjustable over a 3 log unit range in 0.1 log unit steps.