(Hayvan Bilim, Zooloji) 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