Figure 2. Total antioxidant capacity in the blood, aqueous humor, and vitreous of control and diabetic patients. The total antioxidant capacity (TAC) was measured by the oxygen radical absorbance capacity assay in the blood, aqueous humor and vitreous of controls (white columns) and of patients with non-proliferative diabetic retinopathy (NPDR; gray columns) and with proliferative diabetic retinopathy (PDR; black columns). The control group displayed significantly higher TAC levels than diabetic sub-groups in both the vitreous (p<0.001) and aqueous humor (p=0.003). No significant differences were observed in blood. Similar findings emerged from subgroup analyses. PDR patients had decreased TACs in the vitreous and aqueous humors as compared with control subjects (p=0.002 and p=0.003 respectively) and with the NPDR patient subgroup (p<0.001 and p=0.032 respectively). Data are expressed in µmol Trolox Equi/g and represent mean±standard deviation (bars). ANOVA test analysis was used.