MMP9 and metabolic syndrome: While MGD is commonly related to lipid abnormalities, a cohort study suggests that dyslipidemia may be more closely tied to non-MGD forms of DED, possibly through mechanisms involving tear film instability or the upregulation of inflammatory markers such as interleukin-6 (IL-6) and matrix metalloproteinase-9 (MMP-9) (Mussi et al., 2021).