The blood–ocular barrier is a barrier created by endothelium of
capillaries
A capillary is a small blood vessel, from 5 to 10 micrometres in diameter, and is part of the microcirculation system. Capillaries are microvessels and the smallest blood vessels in the body. They are composed of only the tunica intima (the in ...
of the
retina
The retina (; or retinas) is the innermost, photosensitivity, light-sensitive layer of tissue (biology), tissue of the eye of most vertebrates and some Mollusca, molluscs. The optics of the eye create a focus (optics), focused two-dimensional ...
and
iris,
ciliary epithelium and
retinal pigment epithelium
The pigmented layer of retina or retinal pigment epithelium (RPE) is the pigment
A pigment is a powder used to add or alter color or change visual appearance. Pigments are completely or nearly solubility, insoluble and reactivity (chemistry), ...
. It is a physical barrier between the local
blood vessel
Blood vessels are the tubular structures of a circulatory system that transport blood throughout many Animal, animals’ bodies. Blood vessels transport blood cells, nutrients, and oxygen to most of the Tissue (biology), tissues of a Body (bi ...
s and most parts of the
eye
An eye is a sensory organ that allows an organism to perceive visual information. It detects light and converts it into electro-chemical impulses in neurons (neurones). It is part of an organism's visual system.
In higher organisms, the ey ...
itself, and stops many substances including
drug
A drug is any chemical substance other than a nutrient or an essential dietary ingredient, which, when administered to a living organism, produces a biological effect. Consumption of drugs can be via insufflation (medicine), inhalation, drug i ...
s from traveling across it.
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-aqueous barrier is formed by nonpigmented ciliary epithelial cells of the ciliary body and endothelial cells of blood vessels in 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 choriocapillaries into the retina. Formed by endothelium of retinal vessels and epithelium of retinal pigment. ]
See also
*
*
*
*
*
*
References
Human eye anatomy
{{Circulatory-stub