title: Pupillary response to direct and consensual chromatic light stimuli.
abstract: OBJECTIVE
  To assess whether the direct and consensual postillumination (ipRGC-driven) pupil light responses to chromatic light stimuli are equal in healthy subjects.
  
  
  METHODS
  Pupil responses in healthy volunteers were recorded using a prototype binocular chromatic pupillometer (IdeaMedical, Copenhagen), which is capable of both direct and consensual pupillometry measurements. The device uses a pair of dual monochromatic narrow bandwidth LED light sources, red (660 nm) and blue (470 nm). Pupil light responses were recorded with infrared video cameras and analysed using custom-made circuitry and software. Subjects were randomized to receive light stimuli at either the right or left eye after 5 min of dark adaptation. Pupil light responses were recorded in both eyes for 10 seconds before illumination, during illumination and 50 seconds after illumination with red and blue light. Three variables were defined for the recorded pupil responses: the maximal constriction amplitude (CAmax ), the pupil response during illumination and postillumination pupil response (PIPR).
  
  
  RESULTS
  No difference was found in the pupil response to blue light. With red light, the pupil response during illumination was slightly larger during consensual illumination compared to direct illumination (0.54 and 0.52, respectively, p = 0.027, paired Wilcoxon's test, n = 12), while no differences were found for CAmax or the PIPR.
  
  
  CONCLUSIONS
  No difference was found between direct and consensual pupil response to either red or blue light in the postillumination period. Direct and consensual responses can readily be compared when examining the postillumination pupil response to blue light as estimation of photosensitive retinal ganglion cell activation.
authors.affiliation: Department of Ophthalmology, Rigshospitalet - Glostrup, Glostrup, Denmark.
authors.forename: Sindri
authors.initials: S
authors.lastname: Traustason
authors.affiliation: Department of Ophthalmology, Rigshospitalet - Glostrup, Glostrup, Denmark.|Faculty of Health Sciences, Copenhagen University, Copenhagen, Denmark.
authors.forename: Adam Elias
authors.initials: AE
authors.lastname: Brondsted
authors.affiliation: Department of Ophthalmology, Rigshospitalet - Glostrup, Glostrup, Denmark.
authors.forename: Birgit
authors.initials: B
authors.lastname: Sander
authors.affiliation: Department of Ophthalmology, Rigshospitalet - Glostrup, Glostrup, Denmark.|Faculty of Health Sciences, Copenhagen University, Copenhagen, Denmark.
authors.forename: Henrik
authors.initials: H
authors.lastname: Lund-Andersen
mesh_terms: D000328:Adult; D003623:Dark Adaptation; D003941:Diagnostic Techniques, Ophthalmological / Q000295:instrumentation; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D008027:Light; D008297:Male; D008875:Middle Aged; D010775:Photic Stimulation; D011680:Pupil / Q000528:radiation effects*; D012025:Reflex, Pupillary / Q000502:physiology*; D055815:Young Adult
keywords: binocular pupillometer; chromatic pupillometry; intrinsic photosensitive retinal ganglion cells; pupil light reflex