title: Comparison of the Colvard, Procyon, and Neuroptics pupillometers for measuring pupil diameter under low ambient illumination.
abstract: OBJECTIVE
  To compare three different pupillometers (Colvard, Procyon, and Neuroptics) for determining pupil diameter at 0.04 and 0.4 lux ambient illumination.
  
  
  METHODS
  In 92 eyes of 46 healthy volunteers, pupil diameter was measured at 0.04 and 0.4 lux. After dark adaptation for 2 minutes, measurements were performed with each device by two examiners. Interobserver agreement, instrument agreement, and repeatability were analyzed.
  
  
  RESULTS
  Mean pupil diameter was 6.63+/-0.68 mm, 6.24+/-1.01 mm, and 6.99+/-0.67 mm at 0.04 lux and 6.22+/-0.74, 4.64+/-1.04, and 6.73+/-0.72 mm at 0.4 lux with the Colvard, Procyon, and Neuroptics pupillometers, respectively. The interobserver disagreement ranged within narrower limits for the Colvard (0.04 lux: -1.0 to 0.5 mm; 0.4 lux: -0.75 to 1.0 mm) and Neuroptics (0.04 lux: -1.0 to 0.5 mm; 0.4 lux: -1.7 to 0.7 mm) than for the Procyon (0.04 lux: -0.74 to 1.14 mm; 0.4 lux -1.82 to 2.4 mm) under both light conditions. Instrument agreement ranged within narrower limits for the Colvard versus Neuroptics (0.04 lux: -1.3 to 0.75 mm; 0.4 lux: -1.55 to 1.40 mm) than for the Neuroptics versus Procyon (0.04 lux: -1.06 to 2.69 mm; 0.4 lux: 0.18 to 3.69 mm) or Colvard versus Procyon (0.04 lux: -0.63 to 2.60 mm; 0.4 lux: -0.32 to 3.13 mm) at both light levels. At 0.04 lux, repeatability showed no measurement difference outside +/-0.5 mm for the Colvard and Neuroptics; for the Procyon, 25% of consecutive measurements showed a difference >+/-0.5 mm. At 0.4 lux, 2.5% of consecutive measurements for the Colvard and 5% for the Neuroptics differed by >+/-0.5 mm; for the Procyon, 13% of measurements differed by more than this amount.
  
  
  CONCLUSIONS
  Pupil diameters under both light conditions were largest with the Neuroptics pupillometer and smallest with the Procyon. The most "examiner independent" Procyon pupillometer performed poorly. The underestimation of the pupil diameter might have severe consequences for refractive surgery patients. The Neuroptics pupillometer showed a high interobserver agreement and repeatability and therefore high safety.
authors.affiliation: Department of Ophthalmology, University Hospital Essen, University of Duisburg-Essen, Essen, Germany. maurice.schallenberg@uk-essen.de
authors.forename: Maurice
authors.initials: M
authors.lastname: Schallenberg
authors.forename: Valerie
authors.initials: V
authors.lastname: Bangre
authors.forename: Klaus-Peter
authors.initials: KP
authors.lastname: Steuhl
authors.forename: Stephan
authors.initials: S
authors.lastname: Kremmer
authors.forename: J Michael
authors.initials: JM
authors.lastname: Selbach
mesh_terms: D000293:Adolescent; D000328:Adult; 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; D013997:Time Factors; D055815:Young Adult