Melatonin concentrations in aqueous humor of glaucoma patients

PURPOSE: To determine whether glaucoma patients exhibit an abnormal melatonin concentration in aqueous humor. DESIGN: Case-controlled study, laboratory investigation. METHODS: Aqueous humor and plasma samples of 28 patients with primary open-angle glaucoma and 31 non, glaucoma control patients were collected during surgery, and additional plasma samples were taken the night preceding surgery. Melatonin concentrations were determined using direct radioimmunoassay. RESULTS: This study shows detectable concentrations of melatonin in the aqueous humor of healthy humans (45% of subjects) and of glaucoma patients (36% of subjects) sampled in the morning, with similar levels of aqueous humor melatonin concentrations in both groups (6.4 +/- 9.3 standard deviation (SD) pg/ml and 3.6 +/- 1.9 pg/ml, respectively). We find no significant association between the severity of glaucoma and melatonin levels in aqueous humor or in plasma. CONCLUSIONS: Moderate and severe glaucoma does not appear to be associated with abnormal melatonin concentrations in aqueous humor, at least during the morning sampling period assayed in this study.