The Blood-Retinal Barrier (BRB) functions to maintain retinal homeostasis for optimal retinal function. It is made of an inner and outer layer. The inner layer is composed of cells that nourish the cells of the retina. The outer layer contains tight junctions of cells that prevent the passage of most particles through this barrier.
The BRB is crucial in maintaining a healthy and functioning retina. The retina has the highest oxygen consumption per size of any tissue in the body. The BRB is essential in providing the necessary nutrients to the retina for it to maintain such a high metabolic rate. In addition, the outer BRB ensures that photoreceptors in the retina are protected from toxins, and get necessary nutrients from the blood. This is especially important as photoreceptors are an essential part in vision.
Degeneration or breakdown of the BRB is observed in a number of retinal diseases including macular degeneration, glaucoma, diabetic retinopathy, and more. BRB breakdown is not thought to be due to a single factor. Rather, it is thought of as an accumulation of causes over time. One of these is alterations in the proteins found in the tight junctions of the outer layer, which results in leakage through these very important junctions. It can also be due to an increase in vesicular transport across the barrier. Another cause could be due to direct injury to the cells in the barrier.
This being said, the exact cause of BRB breakdown remains unknown. Researchers believe that certain retinal diseases can be prevented or controlled by preventing the breakdown of the BRB. Similarly, the progression of retinal diseases correlates to the breakdown of the BRB. This means that measuring the breakdown of the BRB could be a diagnostic tool for early detection of retinal disease.
Interesting - I like the pictures.