IL6 and proliferative diabetic retinopathy: Conversely, vitreous iron levels in OT were significantly lower than those in retinal diseases such as macular hole (MH), a noninfectious, noninflammatory disease, and proliferative diabetic retinopathy (PDR), a noninfectious inflammation-associated disease characterized by elevated vitreous levels of key inflammatory cytokine markers such as IL6 and MCP-1 [46,47].