Choroid
Choroidea
Sensory (eye & ear)OrgansHeadLeft and right
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- What it is
- A dark, pigmented, blood-rich layer between the sclera and the retina, forming the back part of the uveal tract. Its capillary layer (choriocapillaris) lies against the retinal pigment epithelium.
- Function
- Nourishes the outer retina (photoreceptors) and absorbs stray light inside the eye.
- Size
- About 0.2-0.3 mm thick, thickest at the posterior pole; extends forward to the ora serrata.
- Clinical note
- Choroidal melanoma is the commonest primary eye cancer in adults; the choroid receives one of the highest blood flows per gram of any tissue.