IL6 and retinitis pigmentosa: Elevated levels of IL-6 are present in the vitreous of patients with glaucoma (Franks et al., 1992), PVR (Limb et al., 1991), and retinitis pigmentosa (N. Yoshida et al., 2013b), and IL-6 levels in both the aqueous humour and vitreous increase with diabetic retinopathy disease progression (Funatsu et al., 2005; Wu et al., 2017; Zhou et al., 2012).