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The highly vascular layer of the vertebrate eye, lying between the sclera and the retina.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



the connective-tissue coat of the eye located between the retina and the sciera. It is through the choroid that metabolites and oxygen pass from the blood to the pigmentary epithelium and photoreceptors of the retina.

The choroid includes a suprachoroid layer facing the sciera, a layer of large veins, a layer of arteries and veins, the choriocapil-laris, and Bruch’s membrane. The suprachoroid layer consists of compact reticulin and collagenous fibers. It is rich in fibroblasts and melanocytes, whose processes run through the entire choroid. The arteries and veins of the choroid have a double endothelial lining and basal and adventitial layers. Bruch’s membrane is made up of an amorphous substance containing elastic reticulin and collagenous fibers. It is bounded on the inside by a cell membrane of pigmentary epithelium and on the outside by a porous membrane of capillary endothelium.

The choroid of some fishes and mammals, for example, ungulates, has a reflecting layer, or a mirror, that intensifies the light stimulation of the photoreceptors and increases the sensitivity of the eye to light.


Stebaeva, L. F., and O. V. Volkova. “Ul’trastruktura sosudistoi obo-lochki glaza krolika v norme i pri allergicheskom uveite.” Arkhiv anatomii, gistologii i embriologii, 1974, vol. 66, no. 2.
System of Ophthalmology, vol. 2. Edited by S. Duke-Elder. London, 1961.
Structure of the Eye: Proceedings of the Symposium at the Seventh International Congress of Anatomists. New York-London, 1961.


The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
Knowing that our patient had a suboptimal predictive ETV success score (40) (Table 1) [11], the addition of choroid plexus cauterization was discussed with the parents.
Caption: Figure 1: (a) Diffuse infiltration of the choroid and replacement of the retina by tumor cells (H&E 200x; arrows: Retinal Pigment Epithelium) with a plasmablastic appearance ((b) H&E, 400x).
Thickness of the following layers was measured: ganglion cell layer (GCL), inner plexiform layer (IPL), inner nuclear layer (INL), outer plexiform layer (OPL), outer nuclear layer (ONL), RPE, choroid, and sclera.
A Pearson test was used to correlate VA with the foveal retinal thickness and the choroid thickness.
Fiona Doetsch at the Biozentrum of the University of Basel has now shown that the choroid plexus is a key component of the stem cell niche, whose properties change throughout life and affect stem cell behavior.
These areas are characterized by absence of pigmentation in RPE and in choroid, causing the white sclera to become visible between choroidal blood vessels (Janssens, 2002).
However, the drug must penetrate through several barriers: sclera, choroid and RPE.
The high-resolution molecular map catalogs thousands of proteins in the choroid, which supplies blood and oxygen to the outer retina, itself critical in vision.
Vinit Mahajan, assistant professor in ophthalmology at the UI, said that this molecular map now gives them clues why certain areas of the choroid are more sensitive to certain diseases, as well as where to target therapies and why.
ICG reveals also a welldefined mass and no evidence of hot spots, staining, or leakage of the inner choroid (Figure 2(b)).
In several studies, EDI-OCT has been used to measure the thickness of the choroid, finding its relation with diseases, and monitoring the treatment process [12-14].