FIG 4. Bar graph shows the preventive effect of UV or visible light on the development of vasospasm. Values represent the ratio of the RD in each group on each point to that on day 0 and represent mean ± SD. Although visible light significantly prevented vasospasm (P = .045), UV light was more effective. *, P < .05; **, P < .01 compared with the no irradiation (VS + fiber) group.