Blood-ocular barrier

The blood-ocular barrier is a membrane that controls the passage of substances from the blood into the eye. It is a physical barrier between the local blood vessels and most parts of the eye itself, and stops many substances from traveling across it. The blood-ocular barrier normally keeps most drugs out of the eye. Inflammation can break down this barrier allowing drugs and large molecules to penetrate into the eye. As the inflammation subsides, this barrier usually returns.

It consists of the following components:


 * Blood-aqueous barrier: The ciliary epithelium and capillaries of the iris.
 * Blood-retinal barrier: Non-fenestrated capillaries of the retinal circulation and tight-junctions between retinal epithelial cells preventing passage of large molecules from choriocapillaris into the retina.