S100A4 and open-angle glaucoma: Perhaps most interestingly, although the results indicated that both glaucoma subtypes’ tear fluid changes were connected to inflammatory pathways, distinct differences were observed; for example, S100A4 and S100 calcium-binding protein A8 (S100A8) were upregulated in POAG while CST2 and CST4 were upregulated in PXG patients.