title: Inter- and intraobserver reliability of pupil diameter measurement during 24 hours using the Colvard pupillometer.
abstract: OBJECTIVE
  To evaluate the inter- and intraobserver agreement of pupil size diameter measurements determined using the Colvard pupillometer.
  
  
  METHODS
  The eyes of 69 patients were examined (T1) using the Colvard pupillometer under mesopic and scotopic conditions by two examiners and repeated 1 hour (T2) and 24 hours (T3) later. The limits of agreement (mean difference between measurements +/- 2 standard deviations) were calculated for measurements between examiners (inter-examiner agreement) and between different time points measured by the same examiner (intra-examiner agreement).
  
  
  RESULTS
  At T1, there was a 99% and a 97% chance of two different examiners producing readings within 0.5 mm under mesopic and scotopic conditions, respectively. There was a 15% chance and a 9% chance of finding a pupil difference > 0.5 mm over 1 hour under mesopic and scotopic conditions, respectively. For mesopic and scotopic measurements taken 24 hours apart, there was a 31% chance and a 21% chance, respectively, of finding a difference > 0.5 mm by the same examiner.
  
  
  CONCLUSIONS
  This study showed high interobserver agreement under scotopic conditions, with 98% of measurements between two examiners falling within 0.5 mm, but substantial variability in pupil diameter measurements over 24 hours. These results suggest that serial office measurements may be necessary to establish the true range of pupil size.
authors: Department of Ophthalmology, Francis I. Proctor Foundation, University of California San Francisco, San Francisco, Calif 94143, USA.
authors: Michael K
authors: MK
authors: Yoon
authors: Gregory
authors: G
authors: Schmidt
authors: Thomas
authors: T
authors: Lietman
authors: Stephen D
authors: SD
authors: McLeod
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000886:Anthropometry; D003623:Dark Adaptation; D003941:Diagnostic Techniques, Ophthalmological / Q000295:instrumentation*; D006801:Humans; D007498:Iris / Q000033:anatomy & histology*; D008027:Light; D008875:Middle Aged; D015588:Observer Variation; D011680:Pupil; D015203:Reproducibility of Results