The choroid is the layer of the eyeball
located between the retina
and the sclera
(see the sketch of the back of the eyeball below).
It is a thin, highly vascular (i.e. it contains blood vessels) membrane that is dark brown in colour and contains a pigment that absorbs excess light and so prevents blurred vision (due to too much light on the retina).
The choroid is loosely attached to the inner surface of the sclera by the lamina fusa. The side of the choroid closest to the centre of the eyeball is attached to the retina. This transparent innermost layer of the choroid is called Bruch's Membrane.
The structure of the choroid itself consists mainly of a dense capillary plexus and of many arterioles and venules transporting blood to and from this plexus.
More about Ophthalmology:
This section includes short definitions and descriptions of the parts of the eye.
For other descriptions in this category, choose from the list to the left (but note that this is not a complete / exhaustive list).
Other related sections include:
- A labelled diagram of the eye
- A concise description of the human retina with brief descriptions of the parts of the retina
- Diseases and disorders of the human eye and the human visual system
- Clinical and surgical procedures re. eyes and human visual system
For further information see also our pages of books about ophthalmology.