title: Reaction time in automated kinetic perimetry: effects of stimulus luminance, eccentricity, and movement direction.
abstract: OBJECTIVE
  To determine the effects of stimulus eccentricity and luminance level on the reaction time (RT) of young normal volunteers during automated kinetic campimetry.
  
  
  METHODS
  We used a specially designed video-campimetric device equipped with a continuous infrared (IR) pupillographic fixation control (Tübingen Computer Campimeter) and recorded reaction times upon presenting horizontally moving small circular stimuli (size 26'; constant angular velocity 2 degrees /s) starting at 16 locations within the central 30 degrees -radius of the visual field. Two different levels of stimulus luminance were used (41.6 cd/m(2) and 110 cd/m(2)), while background luminance was 10 cd/m(2). Each stimulus was presented a total of six times in a randomized order. Subjects were 12 healthy young individuals (aged 21-30 years) with normal ophthalmic examinations. An analysis of variance (ANOVA) was performed on the data.
  
  
  RESULTS
  RTs showed considerable inter- and intra-individual variation with individual least squares means (LSM, fitted values of a linear model) ranging from 305 to 454 ms, and residual standard deviation (R.S.D.) 66 ms. Reaction times did not differ significantly as a function of stimulus direction (P>0.6). Higher luminance levels produced significantly reduced reaction times for all stimulus locations and directions (mean reduction: 16 ms; P<0.0001). Reaction times increased with increasing eccentricity, in the mean by 1.8 ms per degree of visual angle, from 365+/-4 ms (S.E.M.) foveally, to 407+/-2 ms at 30 degrees eccentricity; (P<0.0001).
  
  
  CONCLUSIONS
  Automated kinetic perimetry should be designed to cope with significant, variable interindividual response characteristics. Other stimulus related factors, such as eccentricity or luminance level, have a significant but comparatively small effect on reaction time within the central 30 degrees -radius visual field in healthy young individuals.
authors.affiliation: Department II, University Eye Hospital, Schleichstrasse 12-16, D-72076, Tübingen, Germany. ulrich.schiefer@uni-tuebingen.de
authors.forename: U
authors.initials: U
authors.lastname: Schiefer
authors.forename: H
authors.initials: H
authors.lastname: Strasburger
authors.forename: S T
authors.initials: ST
authors.lastname: Becker
authors.forename: R
authors.initials: R
authors.lastname: Vonthein
authors.forename: J
authors.initials: J
authors.lastname: Schiller
authors.forename: T J
authors.initials: TJ
authors.lastname: Dietrich
authors.forename: W
authors.initials: W
authors.lastname: Hart
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D005260:Female; D006801:Humans; D007206:Individuality; D016018:Least-Squares Analysis; D008029:Lighting; D016014:Linear Models; D008297:Male; D009039:Motion Perception / Q000502:physiology*; D011601:Psychophysics; D011930:Reaction Time / Q000502:physiology*; D058609:Visual Field Tests / Q000379:methods*; D014794:Visual Fields / Q000502:physiology*