Blood-retinal barrier

The blood–retinal barrier controls the flux of fluid and blood-borne elements into the neural parenchyma, helping to establish the unique neural environment necessary for proper neural function. Loss of the blood–retinal barrier characterizes a number of the leading causes of blindness including diabetic retinopathy and age-related macular degeneration. In this chapter, the structure of the tight junctions that constitute the blood–retinal barrier will be examined with specific emphasis on the transmembrane tight junction proteins occludin and claudin, which form the seal between adjacent endothelial cells. In addition, alterations that occur to the tight junction proteins in diseases such as diabetic retinopathy will be addressed. Finally, the use of glucocorticoids to restore barrier properties and the effect of this hormone on tight junctions will be discussed.