[Pathogenesis of diabetic macular oedema]

Hyperglycaemia causes breakdown of the blood retina barrier leading to formation of macular oedema and consecutive visual loss. Three major mechanisms are involved in barrier breakdown: increased paracellular permeability of vascular endothelium due to disruption of cell junctions, loss of endothelial cell layer integrity due to cell destruction, and increased transcellular transport through the endothelium. This review focuses on the molecular basis of these mechanisms and discusses the role of cytokines and cellular interactions in blood retina barrier breakdown.