title: Intraocular and interocular symmetry in normal retinal capillary perfusion.
abstract: OBJECTIVE
  To investigate retinal capillary perfusion in different areas of the posterior pole (intraocular symmetry) and to compare capillary perfusion between the right and left eyes (interocular symmetry).
  
  
  METHODS
  The study consisted of 52 clinically healthy patients between the ages of 45 and 74 years. Good quality images were obtained in 30 patients. By using scanning laser Doppler flowmetry with the Heidelberg Retina Flowmeter, three 10 degree scans were obtained from the fovea and superior and inferior retina of the study eye (for intraocular symmetry) and from the fovea of the fellow eye (for interocular comparison). Values of volume, flow, and velocity were recorded from each of these areas. Repeated measures analysis of variance, with Bonferroni correction, was used for groupwise comparison between areas in the study eye. Paired t tests, with Bonferroni correction, were used to compare nonfoveolar perfusion between the right and left eyes for each patient.
  
  
  RESULTS
  Capillary volume in the foveola was significantly less than that in areas superior and inferior and 3 degrees nasal and temporal, and it was found to increase with eccentricity in the macular region. Only 2 of 30 patients had significant interocular differences between the extrafoveolar areas.
  
  
  CONCLUSIONS
  Significant differences in retinal capillary perfusion were found across the macular region and corresponded with the increase in capillary beds. The Heidelberg Retina Flowmeter also measured the expected decrease in volume at the foveolar avascular zone. There were no significant interocular differences in perfusion. Eye movements, media opacities, and poor tear film quality had a deleterious effect on image quality.
authors.affiliation: School of Optometry, University of Waterloo, Ontario, Canada.
authors.forename: M H
authors.initials: MH
authors.lastname: Rawji
authors.forename: J G
authors.initials: JG
authors.lastname: Flanagan
mesh_terms: D000368:Aged; D001783:Blood Flow Velocity / Q000502:physiology; D001794:Blood Pressure; D002196:Capillaries / Q000502:physiology; D005123:Eye / Q000098:blood supply*; D005260:Female; D006801:Humans; D007429:Intraocular Pressure; D017078:Laser-Doppler Flowmetry; D008297:Male; D008875:Middle Aged; D012171:Retinal Vessels / Q000502:physiology*