Prooxidant-antioxidant balance, peroxide and catalase activity in the aqueous humour and serum of patients with exfoliation syndrome or exfoliative glaucoma

Background Oxidative stress plays an important role in the pathobiology of exfoliation syndrome (XFS) and exfoliative glaucoma (XFG). Methods We investigated the prooxidant-antioxidant balance (PAB) in aqueous humour and serum samples of 20 consecutive cases of XFS, 20 of XFG, and 20 age-matched controls, employing a recently described novel assay. The activity of catalase and the levels of (hydrogen) peroxide were also measured in these samples. Results There was no significant difference between the PAB in the aqueous humour of the XFS group (82.5+/-10 AU) and age-matched control patients (78.9+/-13.4 AU; p > 0.05). A significant shift of the PAB balance in favour of oxidants was detected in the XFG group (90.2+/-7.6 AU) compared with controls (p > 0.001). In the serum of patients with XFS (138.8+/-13.2 AU) and XFG (124.08+/-13.50 AU), PAB was significantly altered in favour of oxidants as compared to age-matched controls (114.9+/-9.91 AU); p < 0.001). Catalase activity in the aqueous from XFS (10.1+/-4.5 U/ml) and XFG (12.2+/-6 U/ml) patients was significantly lower than that measured in the normal aqueous (14.6+/-1.9 U/ml). Similarly, a significantly lower catalase activity was found in XFS (103+/-21.4 U/ml) and XFG (116+/-38 U/ml) serum samples compared with controls (189.6+/-84.3 U/ml). Finally, (hydrogen) peroxide concentration in aqueous and serum samples from patients with XFS (aqueous: 26.9+/-6.6 mu M; serum: 41+/-10 mu M) and XFG (aqueous: 21.7+/-7 mu M; serum: 32+/-4 mu M) were significantly higher than that of the controls (aqueous: 9.6+/-5.8 mu M; serum: 24+/-9 mu M; p < 0.001). Conclusions These findings suggest that in XFS oxidative stress is counterbalanced in the aqueous, whereas the development of XFG is accompanied by a disruption of this balance in favour of oxidants.