Is there any difference in human pupillary reaction when different acupuncture points are stimulated?

OBJECTIVES To determine if there is any difference in pupillary response among different acupuncture stimulation sites. METHODS The subjects were 14 healthy males who had no known eye diseases or abnormality in their pupils. They received five different interventions: no acupuncture stimulation (hereinafter 'no-stimulation') and acupuncture stimulation at four sites (TE5, ST7, CV12 and ST36). The Latin square design was used to allocate stimulation order. For all acupuncture stimulation interventions, a disposable acupuncture needle was inserted superficially at the acupuncture point. Gentle repetitive tapping stimulation was applied manually during the subject's exhalation phase of respiration, for 90 s. The pupil diameter was continuously measured for 2 min before stimulation, during stimulation and for 2 min after stimulation. Statistical analysis was conducted on serial changes in pupil diameter during acupuncture stimulation on each respective site and during non-stimulation session by analysis of variance and Fisher (least significant difference) multiple comparison, with linear analysis using a mixed model. RESULTS Pupil diameter reduction occurred at 30 s after stimulation on ST7 (p=0.008) and 60 s after stimulation (p=0.014) compared with pre-stimulation. The decrease of pupillary diameter occurred 60 s after stimulation on TE5 (p=0.028) compared with pre-stimulation. On ST36, CV12 and during the non-stimulation intervention, no significant change in the pupil diameter was observed. CONCLUSIONS Pupillary reaction varies depending on the different stimulation sites.