title: Assessment of pupil size under different light intensities using the Procyon pupillometer.
abstract: OBJECTIVE
  To study the relationship between pupil size and light intensity using the Procyon pupillometer.
  
  
  METHODS
  University based clinic.
  
  
  METHODS
  In this retrospective study, 20 consecutive patients had pupil size assessment with the Procyon pupillometer under 3 different light conditions--4, 0.4, and 0.04 lux. Correlation was established using the log unit of the light intensity and pupil size.
  
  
  RESULTS
  The correlation coefficient for the association between pupil size and log unit of light intensity in all eyes was significant (P<.001). The mean correlation coefficient for the association between pupil size and log unit of light intensity in all patients was 0.968 +/- 0.089 (SD) in the right eye and 0.970 +/- 0.031 in the left eye.
  
  
  CONCLUSIONS
  The linear relationship between the pupil size and the log unit of the light intensity showed a tight correlation in all cases. These results can be useful in the comparing pupil size with pupillometers that work under different light conditions.
authors.affiliation: Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, University Eye Center, Hong Kong Eye Hospital, Kowloon, Hong Kong, People's Republic of China. artcheng@netvigator.com
authors.forename: Arthur C K
authors.initials: AC
authors.lastname: Cheng
authors.forename: Srinivas K
authors.initials: SK
authors.lastname: Rao
authors.forename: Lulu L
authors.initials: LL
authors.lastname: Cheng
authors.forename: Dennis S C
authors.initials: DS
authors.lastname: Lam
mesh_terms: D000328:Adult; D000886:Anthropometry; D003941:Diagnostic Techniques, Ophthalmological / Q000295:instrumentation; D005260:Female; D006801:Humans; D007498:Iris / Q000033:anatomy & histology; D008027:Light; D008297:Male; D011680:Pupil / Q000502:physiology*; D012025:Reflex, Pupillary / Q000528:radiation effects*; D012189:Retrospective Studies