title: Variability of the main sequence.
abstract: OBJECTIVE
  This study investigated the relationship between amplitude and peak velocity of saccadic eye movements (the so-called main sequence) and the intra-individual variability of the main sequence.
  
  
  METHODS
  Saccadic amplitudes and peak velocities were measured twice in 58 healthy subjects with an infrared reflection technique.
  
  
  RESULTS
  Considerable intra-individual variability was found between the first and second recordings.
  
  
  CONCLUSIONS
  Intra-individual variability of saccadic peak velocity affects the interpretation of changes in repeated recordings of peak velocities, such as before and after medication is administered. Furthermore, considerable intra-individual variability decreases the probability that statistically significant differences between patients and control subjects can be detected, especially when groups are small. Calculating the intraclass correlation coefficient allows the number of subjects in comparative studies to be determined.
authors.affiliation: Department of Neurology, University Hospital, Leiden, The Netherlands.
authors.forename: E
authors.initials: E
authors.lastname: Bollen
authors.forename: J
authors.initials: J
authors.lastname: Bax
authors.forename: J G
authors.initials: JG
authors.lastname: van Dijk
authors.forename: M
authors.initials: M
authors.lastname: Koning
authors.forename: J E
authors.initials: JE
authors.lastname: Bos
authors.forename: C G
authors.initials: CG
authors.lastname: Kramer
authors.forename: E A
authors.initials: EA
authors.lastname: van der Velde
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D009885:Ophthalmology / Q000379:methods; D015203:Reproducibility of Results; D012438:Saccades / Q000502:physiology*