Editing Choroid (section)

==Mechanism==
[[Melanin]], a dark colored pigment, helps the choroid limit uncontrolled reflection within the eye that would potentially result in the perception of confusing images.

In humans and most other [[primates]], melanin occurs throughout the choroid. In [[albino]] humans, frequently melanin is absent and [[low vision|vision is low]].  In many animals, however, the partial absence of melanin contributes to superior [[night vision]]. In these animals, melanin is absent from a section of the choroid and within that section a layer of highly reflective tissue, the [[tapetum lucidum]], helps to collect light by reflecting it in a controlled manner.  The uncontrolled reflection of light from dark choroid produces the photographic [[red-eye effect]] on photos, whereas the controlled reflection of light from the tapetum lucidum produces [[eyeshine]] (see [[Tapetum lucidum]]).