Definition for Pecten oculi
From Biology Forums Dictionary
The pecten or pecten oculi is a comb-like structure of blood vessels belonging to the choroid in the eye of a bird. It is non-sensory and is a pigmented structure that projects into the vitreous body from the point where the optic nerve enters the eyeball. The pecten is believed to both nourish the retina and control the pH of the vitreous body. It is present in all birds and some reptiles.
In the vertebrate eye, blood vessels lie in front of the retina, partially obscuring the image. The pecten helps to solve this problem, lifting the blood vessels away from the retina and leading to the extremely sharp eyesight of birds such as hawks. The pigmentation of the pecten is believed to protect the blood vessels against damage from ultraviolet light. The structure varies across birds and is conical in the kiwi, vaned in the ostrich and pleated in most other birds.
