Long-chain unsaturated fatty acids as possible important metabolites for primary angle-closure glaucoma based on targeted metabolomic analysis.

Primary angle-closure glaucoma (PACG) is a severe chronic neurodegenerative disease in Asia. Identification of important metabolites associated with PACG is crucial for early intervention and advancing knowledge of the disease mechanism. We applied gas chromatography-mass spectrometry (GC-MS) for targeted metabolomic analysis on serum samples from 38 newly diagnosed PACG patients and 48 controls. Palmitoleic acid (PA), linoleic acid (LA), γ-linolenic acid (GLA) and arachidonic acid (ARA) were identified as important metabolites associated with PACG. PA and GLA were significantly elevated (p < 0.05), while LA and ARA showed a significantly decreased trend (p < 0.05) in PACG group compared with the control group. Also, significant negative correlations were observed between LA and ARA levels and intraocular pressure of the left eye (rs = -0.750, p < 0.001; rs = -0.729, p < 0.001) and the right eye (rs = -0.786, p < 0.001; rs = -0.764, p < 0.001). Serum GLA level was positively correlated with intraocular pressure of the left eye (rs = 0.233, p = 0.031) and the right eye (rs = 0.226, p = 0.036). Our findings revealed a significant difference of the serum free fatty acid metabolic profiles between PACG patients and control subjects. Furthermore, PA, LA, ARA and GLA appear to have clinical applications for the screening of PACG.