Homocysteine and nitric oxide levels in plasma of patients with pseudoexfoliation syndrome, pseudoexfoliation glaucoma, and primary open-angle glaucoma

Purpose: To evaluate plasma total homocysteine (tHcy) and nitric oxide (NO) marker levels in patients with pseudoexfoliation syndrome (PXS), pseudoexfoliation glaucoma (PXG), primary open-angle glaucoma (POAG), and normal controls. Methods: This cross-sectional, prospective study involved 19 patients with POAG, 18 with PXS, 22 with PXG, and 20 control subjects. Fasting tHcy levels of all study participants were determined using a fluorescence polarization immunoassay method. Quantitation of total nitrate was based on the Griess reaction, in which a chromophore with a strong absorbance at 545 nm is formed by reaction of nitrite with a mixture of naphthylethylenediamine and sulphanilamide. Results: The mean plasma homocysteine level was statistically significantly elevated in the PXS (p=0.033) and the PXG (p=0.023) groups but not in the POAG group (p=0.996) when compared with the control group. Multiple logistic regression analyses comparing the various patient groups with the single control group indicated that elevation in plasma homocysteine concentration was a significant risk factor for PXS (odds ratio per 1 mu mol/l increase in homocysteine concentration=2.05, 95% CI=1.19-3.52) and PXG (odds ratio per 1 mu mol/l increase in homocysteine concentration=1.36, 95% CI=1.00-1.85) but was not a significant risk factor for POAG (odds ratio per 1 mu mol/l increase in homocysteine concentration=0.99, 95% CI=0.78-1.26). NO markers levels were found to be slightly higher in PXS and PXG patients than control and POAG patients but the differences were not statistically significant (p=0.151). Multiple logistic regression analyses comparing the various patient groups with the single control group indicated that elevation in NO marker concentration was not a significant risk factor for PXS (odds ratio per 1 mu mol/l increase in NO concentration=1.00, 95% CI=0.99-1.01), PXG (odds ratio per 1 mu mol/l increase in NO concentration=1.00, 95% CI=0.99-1.00) and POAG (odds ratio per 1 mu mol/l increase in NO concentration=0.99, 95% CI=0.99-1.00). No statistically significant correlations were observed between plasma tHcy and NO markers in study groups (p > 0.05). Conclusion: Elevated levels of homocysteine in pseudoexfoliation patients with and without glaucoma may partly explain the increased risk of vascular disease among patients with pseudoexfoliation. No significant difference was found in plasma NO markers among the POAG, PXS, PXG, and the control subjects.