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 nonglaucoma 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.