Figure 4. Relative dichlorofluorescein fluorescence. The formation of reactive oxygen species (ROS) was assayed by measuring the fluorescence of dichlorofluorescein (DCF). Each value represents the mean±SD. The asterisk indicates p<0.05, in comparison with the control group. A indicates HCECs from a 40-year-old donor. B indicates HCECs froma 33-year-old donor.