Pecten oculi

It is a non-sensory, pigmented structure that projects into the vitreous humor from the point where the optic nerve enters the eyeball.

[4] In the vertebrate eye, there are blood vessels in front of the retina, partially obscuring the image.

The pecten helps to solve this problem by greatly reducing the number of blood vessels in the retina and leading to the extremely sharp eyesight of birds such as hawks.

[5] The pigmentation of the pecten is believed to protect the blood vessels against damage from ultraviolet light.

Stray light absorption by melanin granules of pecten oculi is also considered to give rise to small increments in temperature of pecten and eye; this may offer increased metabolic rate to optimize eye physiology in low temperatures at high-altitude flights.