Editing Choroid (section)

{{Short description|Vascular layer of the eye}}
{{Infobox anatomy
| Name        = Choroid
| Latin       = choroidea
| Image       = File:Blausen 0388 EyeAnatomy 01.png
| Caption     = Cross-section of [[human eye]], with choroid labeled at top.
| Image2      = Gray875.png
| Caption2    = Interior of anterior half of bulb of eye. (Choroid labeled at right, second from the bottom.)
| Artery      = [[Short posterior ciliary arteries]], [[long posterior ciliary arteries]]
| System      =
| Precursor   =
}}

The '''choroid''', also known as the '''choroidea''' or '''choroid coat''', is a part of the [[uvea]], the [[Blood vessel|vascular]] layer of the [[eye]]. It contains [[connective tissue]]s, and lies between the [[retina]] and the [[sclera]].  The human choroid is thickest at the far extreme rear of the eye (at 0.2&nbsp;mm), while in the outlying areas it narrows to 0.1&nbsp;mm.<ref name="choroid">[http://www.mrcophth.com/MRCOphth/saqpart12004/SAQ2004answer6.html MRCOphth Sacs questions]</ref> The choroid provides [[oxygen]] and nourishment to the outer layers of the [[retina]].  Along with the [[ciliary body]] and [[Iris (anatomy)|iris]], the choroid forms the [[Uvea|uveal tract]].

The structure of the choroid is generally divided into four layers (classified in order of furthest away from the retina to closest):
*Haller's layer – outermost layer of the choroid consisting of larger diameter blood vessels;<ref name="choroid"/>
*[[Sattler's layer]] – layer of medium diameter blood vessels;<ref name="choroid"/>
*[[Capillary lamina of choroid|Choriocapillaris]] – layer of capillaries;<ref name="choroid"/> and
*[[Bruch's membrane]] (synonyms: Lamina basalis, Complexus basalis, Lamina vitra) – innermost layer of the choroid.<ref name="choroid"/>