title: [Measuring leukocyte velocity in macular capillaries using a miniaturized blue field simulator: effect of aperture of the pupil].
abstract: BACKGROUND
  In this paper we present a miniaturized blue field simulator (BFS) which allows the measurement of the velocity (V) pulsatility (P) and number (D) of leukocytes in the macular retinal capillaries. A study on the effect of the aperture size of the blue light source at the subject's pupil on the measured flow parameters was performed.
  
  
  METHODS
  A blue field entoptoscope with a small halogen lamp was used to induce the perception of the "flying corpuscles" and a flat color screen was selected to display a computer simulation of this entoptic phenomenon. The aperture of the blue light source at the pupil was varied by a diaphragm placed at a conjugate pupil plane while the size and retinal irradiance of the blue field stimulus at the fundus was held constant.
  
  
  RESULTS
  The results show significant correlations between log pupil area and both V (-18% per log unit) and D (+42% per log unit). When the retinal illuminance is expressed in Log Trolands, V shows no dependency, but D is strongly correlated (+40% per log Troland).
  
  
  CONCLUSIONS
  When applying the BFS technique, the size of the blue light stimulus at the pupil, if undilated, must be well controlled to minimize instrument-related variations of the blood flow measurements.
authors.affiliation: Institut de Recherche en Ophtalmologie, Sion.
authors.forename: B L
authors.initials: BL
authors.lastname: Petrig
authors.forename: B
authors.initials: B
authors.lastname: Lorenz
authors.forename: S D
authors.initials: SD
authors.lastname: Cranstoun
authors.forename: C E
authors.initials: CE
authors.lastname: Riva
mesh_terms: D000328:Adult; D001783:Blood Flow Velocity / Q000502:physiology; D002196:Capillaries / Q000502:physiology; D005260:Female; D006801:Humans; D007962:Leukocytes; D008266:Macula Lutea / Q000098:blood supply*; D008297:Male; D008875:Middle Aged; D010775:Photic Stimulation / Q000295:instrumentation*; D012016:Reference Values; D012025:Reflex, Pupillary / Q000502:physiology*; D014788:Vision, Entoptic / Q000502:physiology*