Plasma and aqueous humour levels of homocysteine in exfoliation syndrome

Background: Recent studies have suggested that the relationship between elevated plasma homocysteine (Hey) and increased risk of vascular disease holds also for certain diseases of the eye with vascular aetiology. Elevated plasma Hey levels have been noted among patients with exfoliation syndrome (XFS). The purpose of this study was to establish whether subjects with XFS have higher plasma and aqueous humour Hey levels values than non-XFS subjects, particularly in relation to vitamin B status. Methods: Using a cross-sectional study design, 36 subjects with XFS and 36 non-XFS subjects with intraocular pressure (IOP) lower than 23 mmHg, matched by age and gender, were first selected. The participant exclusion criteria included parameters known to alter Hey metabolism. In the XFS group, 11 subjects had a concurrent diagnosis of exfoliative glaucoma (XFG). Fasting plasma and aqueous humour Hey samples were collected, along with erythrocyte folate (E-Fol) and serum vitamin B6 and B12 samples. The Hey samples were analysed using a fluorescence polarization immunoassay method. Results: Plasma Hey level was significantly higher (P=0.020, after Bonferroni correction for multiple testing) in the XFS group than in the controls. The Hey concentrations in the aqueous humour did not differ statistically between the two groups. Plasma and aqueous humour Hey concentrations were not statistically significantly correlated within the groups of exfoliation-positive and -negative subjects. E-Fol, and serum vitamin B6 and B 12 levels did not differ statistically between the XFS group and the control group. Conclusions: The finding that subjects with XFS are more prone to elevated plasma Hey emphasizes exfoliation as a clinical sign and a marker of thromboembolic vasculopathies induced by hyperhomocysteinaemia.