Increased Urinary 8-Hydroxy-2′-deoxyguanosine (8-OHdG)/Creatinine Level is Associated with the Progression of Normal-Tension Glaucoma

Purpose: The objective of this study was to investigate the association between systemic oxidative stress and visual field defect progression in normal-tension glaucoma (NTG). Patients and methods: The subjects were 40 consecutive patients with NTG who were admitted to Keio University Hospital for 24-h intraocular pressure (IOP) evaluation; all subjects underwent six or more visual field tests in either eye and were followed up for >5 years. Spot samples of morning urine were collected during admission from all participants to determine the levels of urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) by ELISA kit. A linear regression line was calculated with the least squares method. Those subjects whose regression lines were negative and the p value <0.05 were classified as progressive, while all others were defined as non-progressive. Urinary 8-OHdG/creatinine level was compared between the two groups. Adjusted odds ratio and 95% confidence intervals for the progression were estimated with logistic regression models. Results: Seventeen subjects showed visual field defect progression (age: 59.9 +/- 9.5 years, untreated IOP in the right eye: 15.8 +/- 2.1 mmHg), and 23 subjects showed no progression (age: 57.4 +/- 10.4 years, untreated IOP in the right eye: 16.0 +/- 2.6 mmHg). Urinary 8-OHdG/creatinine level was significantly higher in the progressive group than in the non-progressive group (progressive group: 9.0 +/- 2.4 ng/mg creatinine, non-progressive group: 7.3 +/- 1.8 ng/mg creatinine, p = 0.02). Multivariable analysis revealed that higher urinary 8-OHdG/creatinine level was a significant risk factor for the progression (odds ratio 1.54, 95% confidence interval 1.03-2.29). Conclusions: Increased urinary 8-OHdG/creatinine was associated with glaucomatous visual field progression in subjects with NTG.