Oleic acid association with primary angle-closure glaucoma: A finding using metabolomics.

Metabolomics has been used to study ophthalmic diseases for the past several years. However, there was rare metabolomics study was reported about primary angle-closure glaucoma (PACG). The purpose of this study was to explore a two-step metabolomics analysis method for identifying differential metabolites in the aqueous humor of patients with PACG. Aqueous humor samples were collected from 20 patients each with age-related cataracts, acute PACG, and chronic PACG. In the first step, the changed metabolites were identified using a non-targeted metabolic analysis. In the second step, metabolites showing consistent changes in both acute and chronic PACG groups were selected for targeted metabolic analysis. Further, correlation analysis was performed to study the correlation between differential metabolites and clinical data. The results demonstrated that 7495 metabolites were identified using non-targeted metabolomics methods; subsequently, seven consistently changed metabolites, including oxoadipic acid, heptanoic acid, oleic acid, quinolinic acid, 25-hydroxycholesterol, mannitol, and maleic acid, were selected in the PACG groups. Except for quinolinic acid, the other metabolites were identified using targeted metabolomics analysis. However, to avoid clinical drug bias, mannitol and maleic acid were excluded from further statistical analyses. The PACG groups showed a tendency towards higher oleic acid and oxoadipic acid contents, whereas only oleic acid was negatively correlated with sex and logarithm of the minimum angle of resolution vision. These findings not only indicate that oleic acid may be involved in the development of pathological changes in eyes with PACG but also provide a method for identifying differential metabolites for other clinical diseases.