Investigators have identified amino acid-associated metabolites and insulin secretions in vitreous and aqueous humor samples that may be associated with pathological myopia (PM), according to a study published in Experimental Eye Research.
Researchers collected 100 microliters (μL) of aqueous humor (AH) and 2 milliliters (mL) of vitreous humor (VH) from participants with PM (n=30; mean age, 57.83±6.60 years; 23 women) and age- and sex-matched control individuals (n=30; mean age, 57.63±9.32; 22 women). Participants underwent non-targeted metabolomics analysis using ultra-high-performance liquid chromatography with mass spectrometry. Patients with axial length (AL) exceeding 26.5 mm and foveoschisis or macular hole (MH) were included in the study.
A total of 508 metabolites were identified in the AH and 601 were noted in the VH. Statistical evaluation revealed that 104 metabolites in the AH and 114 metabolites in the VH were significantly different between the two groups (P <.05).
Four metabolic pathways enriched in both AH and VH were identified to be associated with PM. These included bile secretion, insulin secretion, thyroid hormone synthesis, and cGMP-PKG signaling pathways. Among the differently expressed AH and VH metabolites in patients with PM, 47 and 68, respectively, were higher compared with the control group. A total of 57 and 46, respectively, were lower compared with the control group. Overall, 10 AH metabolites were significantly different in patients with PM compared with control individuals (8 with higher concentrations in the PM group, 2 with lower concentrations). A total of 10 metabolites were also significantly different in the VH between patients with PM and control individuals (6 with higher concentrations in the PM group, 4 with lower concentrations.
“Discovering new metabolite markers in PM could shed light on the possible pathological processes and aid developing risk stratification and novel therapeutic strategies,” according to the researchers. “The metabolite differences in AH and VH between PM and controls can reflect changes in the microenvironments of the eye in cases of retinopathy and choroidopathy, and can serve as an alternative to obtaining human retinal and choroidal specimens, which are difficult to collect.”
Study limitations include potential confounding due to measurement and preservation methods and the timing of specimen collection during the day. It is also limited by a small sample size.
Lian P, Zhao X, Song H, et al. Metabolic characterization of human intraocular fluid in patients with pathological myopia. Exp Eye Res. Published online July 9, 2022. doi:10.1016/j.exer.2022.109184