Reduced plasma oxytocin levels in patients with open-angle glaucoma.

Purpose: We explored the role of oxytocin in glaucoma by measuring the blood levels of oxytocin in glaucoma patients, comparing them to normal control subjects, and examining its association with clinical parameters.

Study design: Retrospective cross-sectional study.

Material and methods: After obtaining informed consent from 181 glaucoma patients and 44 age-matched control participants, we collected blood samples in ethylenediaminetetraacetic acid (EDTA) tubes and centrifuged them at 2000 g for 25 minutes at 4 °C. The resulting plasma was assayed for oxytocin concentration with an Enzyme Linked Immunosorbent Assay (ELISA) kit. We compared oxytocin concentrations in the control and glaucoma groups, and within the glaucoma group, we determined whether the oxytocin levels were correlated with mean deviation (MD) and sectoral total deviation (TD). Furthermore, in 33 patients who underwent at least five visual field tests over a two-year period following oxytocin measurements and received no surgical interventions during that time, we determined whether the oxytocin levels were correlated with MD slope and sectoral TD slopes.

Results: Oxytocin levels in glaucoma patients were significantly lower than in age- and sex-matched normal controls (723.34 ± 303.44 vs. 557.59 ± 296.04 pg/ml, p=0.002). In glaucoma patients, oxytocin levels were significantly correlated with MD and inferior TD after adjustment for age and sex (β=0.149, p=0.041; β=0.156, p=0.034, respectively). There was a weak negative correlation between oxytocin concentration and MD slope (β=-0.334, p=0.084) and a weak negative correlation with central TD slope (β=-0.405, p=0.039), adjusted for age, sex, and history of additional eye drops.

Conclusion: Oxytocin concentrations in glaucoma patients were significantly lower than in normal subjects and associated with the severity and progression of visual field defects. Given the wide variety of the pharmacological actions of oxytocin, it may be involved in the pathogenesis of glaucoma. Our results suggest that plasma oxytocin measurements may open a new avenue for glaucoma care.