Related Experiment Videos
[Effect of caffeine on microcirculation of human ocular fundus]
T Okuno1, T Sugiyama, M Tominaga
1Department of Ophthalmology, Osaka Medical College, 2-7 Daigakucho, Takatsuki 569-8686, Japan.
Purpose:
To determine the effect of caffeine on the microcirculation in the human ocular fundus.
Subjects And 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.