Clearly, the high concentrations of taurine in the RPE and photoreceptors may contribute to the relative sparing of the distal retina, which occurs despite the fact that hyperglycemia causes altered expression of the tight-junctional protein occludin [89], an increase in the lipid content of the RPE [90], and permeability defects in the RPE [91]. Here, OCLN is linked to Hyperglycemia.