Tight junctions are physical barriers that limit the paracellular diffusion of solutes and ions. The blood-retina barriers are cellular barriers composed of tight junctions established in retinal pigment epithelial (RPE) cells and retinal endothelial cells to maintain retinal homeostasis. Claudins are the major components of tight junctions, and their dysregulation leads to impaired blood-retina barrier integrity, resulting in retinal diseases with concomitant local inflammation. In this chapter, we introduce two important claudins, claudin-5 and -19, and briefly explain how decreased expression of these claudins is associated with the progress of diabetic retinopathy (DR) and age-related macular degeneration (AMD) by compromising the blood-retina barriers.