Serotonin and hydroxyindolacetic acid levels in aqueous humor of patients with primary open-angle glaucoma

Purpose: To investigate the levels of 5-HT (serotonin, 5-hydroxytryptamine) and 5-HIAA (5-hydroxyindolacetic acid) in the aqueous humor and plasma of subjects with primary open-angle glaucoma (POAG) and to correlate their concentrations with the severity of glaucoma. Methods: Thirty-five patients with POAG and 30 patients with senile cataract (control group) of matched age and gender were included in the study prospectively. Aqueous humor samples were obtained by paracentesis from glaucoma and cataract patients who were undergoing elective surgery. Aqueous humor and corresponding plasma samples were analyzed for 5-HT and 5-HIAA levels by high performance liquid chromatography with electrochemical detection. Results: 5-HT and 5-HIAA levels were significantly higher in the aqueous humor of POAG patients than in that of the comparative group of cataract patients. There was no significant difference in the 5-HT and 5-HIAA levels in plasma of POAG and cataract patients. A positive correlation was found between 5-HT and 5-HIAA in the aqueous humor of POAG patients. The 5-HT turnover (5-HIAA/5-HT) was higher in POAG than in cataract patients, but the difference was not significant. No significant correlation was found between levels and severity of visual field loss. Conclusion: Increased levels of 5-HT and 5-HIAA aqueous humor may be associated with POAG.