Related Experiment Video
Updated: Aug 17, 2026
Assessing Pupil-linked Changes in Locus Coeruleus-mediated Arousal Elicited by Trigeminal Stimulation
Published on: November 26, 2019
Pupil size and Perimetry--a pharmacological model using increment and decrement stimuli
David D Martin1, Reinhard Vonthein, Helmut Wilhelm
1Department of Pathophysiology of Vision and Neuro-Ophthalmology, University Eye Hospital, Tuebingen University, Schleichstr. 12-16, 72076 Tübingen, Germany.
Background:
To assess the influence of natural and pharmacologically induced pupil size fluctuations on differential luminance sensitivity threshold (DLS) using bright (increment) and dark (decrement) stimuli.
Methods:
Twelve healthy volunteers (20-30 years) were examined under the effect of phenylephrine 2%, dapiprazole 0.5%, and placebo. Pupil size was recorded by infra-red video camera in sessions without and with visual field examination (Tübingen Computer Campimeter). DLS was estimated at 9 locations within the central 20 degrees visual field, using bright and dark 26 min-of-arc-stimuli (10 cd/m(2) background, 4-2-1 dB thresholding strategy, four reversals).
Results:
There were substantial inter-individual differences in pupil size and pupil size fluctuations. Intra-individual differences were small. Independently of medication, pupil size fluctuations were reduced by more than one-third when a subject was undergoing perimetric examination. Pupil size affected DLS on its own (slope 0.21 dB/mm; 95% CI: 0.09-0.33 dB/mm), differently at different stimulus locations, and to a greater extent with increment than with decrement stimuli (slope difference 0.13 dB/mm; 95% CI: 0.00-0.26 dB/mm).
Conclusions:
Campimetric examinations have a stabilising effect on pupil size fluctuations. Pupil size affects DLS with bright stimuli more than with dark stimuli; in normal young subjects this effect is not relevant for clinical or normative studies.
