Plasma amino acid metabolic alterations and their associations with ocular parameters in early primary angle-closure...

To explore the plasma metabolite profiles of patients with early primary angle-closure glaucoma (PACG) and investigate their relevance to ocular characteristics and retinal-associated parameters.

Plasma samples were obtained from 30 early PACG patients and 30 healthy controls for untargeted and targeted metabolomics analysis. Additionally, relevant clinical data such as ocular characteristics and retinal-associated parameters were collected. Correlations between clinical data and differential metabolites were further analyzed.

A total of 439 differential metabolites were identified through untargeted metabolomics analysis, with amino acids being the most abundant category among the differential metabolites. Amino acid-targeted metabolomics revealed that L-alanine, L-lysine, citrulline, L-tyrosine, and glycylglycine were significantly elevated in early PACG (all P < 0.05). In addition, intraocular pressure (IOP) was significantly higher (20.9 ± 2.5 vs. 14.2 ± 2.4 mmHg, P < 0.001), axial length (AL) was shorter (22.8 ± 0.1 vs. 23.2 ± 0.2 mm, P < 0.001), and lens thickness (LT) was greater (4.8 ± 0.2 vs. 4.3 ± 0.2 mm, P < 0.001) in early PACG patients than in healthy controls. Reduced retinal nerve fiber layer (RNFL) thickness, ganglion cell complex (GCC) thickness, and superficial vascular complex vessel density in the peripapillary and macular regions were observed in early PACG patients compared with healthy controls (all P < 0.05). We further identified five amino acids that showed a positive correlation with IOP and LT, and a negative correlation with AL, as well as with the thickness of the RNFL and GCC in the central 3-6 mm annular region (all P < 0.05).

The plasma of early PACG patients showed distinctive metabolic profiles, which provided new insights into the pathogenesis of the early phase of PACG patients.