IL6 and glaucoma: Although the pooled result indicated that glaucoma patients tend to have higher IL-6 levels (SMD = 0.8, 95% CI 0.26–1.35, P = 0.004, Fig. 2A, Supplemental Table S4), only secondary glaucoma (which contributed 36.2% towards the total weight) showed a significant increase of IL-6 levels compared to control (SMD = 1.84, 95% CI 0.59–3.09, P = 0.004), but not to POAG or PACG (Fig. 2A, Supplemental Table S4).