title: Post-illumination pupil response in subjects without ocular disease.
abstract: OBJECTIVE
  A sustained pupilloconstriction is often observed after the cessation of a bright visual stimulus. This post-illumination pupil response (PIPR) is produced by the intrinsically photosensitive retinal ganglion cells (ipRGCs). The present study was designed to examine the characteristics of the PIPR in a normal population without ocular disease.
  
  
  METHODS
  Thirty-seven subjects (mean age, 48.6 years) were tested by presenting a 60 degrees, 10-second light stimulus (13 log quanta/cm(2)/s retinal irradiance) and recording pupillary responses for 50 seconds after light cessation. The light stimuli (470 [blue] and 623 [red] nm) were presented by an optical system to one eye after dilation, while the consensual pupil response of the fellow, undilated eye was recorded by infrared pupillometry.
  
  
  RESULTS
  A positive PIPR was seen in all subjects tested. The population average of the PIPR for 470-nm light was 1.5 mm (SEM 0.10, P < 0.05) and the net PIPR (blue PIPR minus red PIPR) was 1.4 mm (SEM 0.09, P < 0.0001). The net PIPR correlated positively with baseline pupil diameter (P < 0.05), but not significantly with age, race, or sex (P > 0.05) in the test population.
  
  
  CONCLUSIONS
  All normal subjects displayed a significant PIPR for a 10-second, 470-nm light stimulus, but not a 623-nm stimulus, which is consistent with the proposed melanopsin-mediated response. In most normal individuals, the amplitude of the PIPR was substantial. This test has the potential to be used as a tool in evaluating subjects with inner retinal dysfunction or melanopsin-related disorders.
authors.affiliation: Department of Vision Sciences, University of Alabama at Birmingham, Birmingham, AL 35294, USA. klkanth@uab.edu
authors.forename: Laxmikanth
authors.initials: L
authors.lastname: Kankipati
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Girkin
authors.forename: Paul D
authors.initials: PD
authors.lastname: Gamlin
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008027:Light; D008297:Male; D008875:Middle Aged; D020419:Photoreceptor Cells, Vertebrate / Q000378:metabolism; D011680:Pupil / Q000502:physiology*; D012025:Reflex, Pupillary / Q000528:radiation effects*; D012164:Retinal Diseases / Q000175:diagnosis / Q000378:metabolism; D012165:Retinal Ganglion Cells / Q000378:metabolism; D017299:Rod Opsins / Q000378:metabolism; D000099210:Melanopsin
chemical_list: D017299:Rod Opsins; D000099210:Melanopsin