title: [Effect of caffeine on microcirculation of human ocular fundus].
abstract: OBJECTIVE
  To determine the effect of caffeine on the microcirculation in the human ocular fundus.
  
  
  METHODS
  The microcirculation of the ocular fundus in 10 eyes of 10 healthy volunteers was studied using a laser speckle tissue circulation analyser. 100 mg of caffeine or placebo was given orally in a double-blind test. Square blur rate(SBR), a quantitative index of blood flow velocity, was measured in the temporal site of the optic nerve head(ONH) free of surface vessels and in the middle site of the choroid-retina between the ONH and the macula. Intraocular pressure(IOP), blood pressure(BP), pulse rate(PR), and central critical fusion frequency(CFF) were also measured. These parameters were measured before and for 2 hours after administration. The area under curve(AUC), of the SBR was calculated for each area. Ocular perfusion pressure(OPP) was also obtained from blood pressure and intraocular pressure.
  
  
  RESULTS
  The time-course change of SBR value showed much individual difference. Caffeine decreased the AUC of the SBR in the ONH as well as in the choroid-retina significantly. IOP, mean BP, PR, OPP and central CFF did not change significantly.
  
  
  CONCLUSIONS
  These results suggest that caffeine may increase blood vessel resistance and decrease blood flow in the ONH and choroid-retina in humans.
authors.affiliation: Department of Ophthalmology, Osaka Medical College, 2-7 Daigakucho, Takatsuki 569-8686, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Okuno
authors.forename: T
authors.initials: T
authors.lastname: Sugiyama
authors.forename: M
authors.initials: M
authors.lastname: Tominaga
authors.forename: S
authors.initials: S
authors.lastname: Kojima
authors.forename: T
authors.initials: T
authors.lastname: Ikeda
mesh_terms: D000328:Adult; D002110:Caffeine / Q000494:pharmacology*; D004311:Double-Blind Method; D005260:Female; D005654:Fundus Oculi; D006801:Humans; D008297:Male; D008833:Microcirculation / Q000187:drug effects; D012039:Regional Blood Flow / Q000187:drug effects; D012171:Retinal Vessels / Q000187:drug effects*; D014655:Vascular Resistance / Q000187:drug effects
chemical_list: D002110:Caffeine