it is part of the Squids eye Sight...
Optic nerve and occulomotor nerve
The optic nerve is a group of nerve fibers that function to provide vision. The optical never works by transferring electrical impulses to the brain from a part of the eyes known as the retina.
Occipital nerve. It is the second cranial nerve.
so the squid can see it's prey and predators and other objects
Optic nerve and ophthalmic artery passes through this foramen to your eye ball.
As with all nerves in the human body, the optic nerve transmits information. In this case, the optic nerve specifically transmits information from the retina of the eye to the brain for analysis and integration, resulting in the perception of "sight."
It is not a function, it is where the optic nerve connect from the eye to the brain. Because of this there are no photo-receptors at that point.
That should be the shutter.
Point where optic nerve enters eyeball is the optic disc.
Optic disc:The optic disc is also called the blind spot. There are no receptors in this part of the retina. This is where all of the axons of the ganglion cells(last neurons before optic nerve) exit the retina to form the optic nerve.
The junction between the retina and the optic nerve is the optic disc.
Optic nerve. Well, it connects the retina to the brain. The muscles of the eye also connect to the brain, but not through the optic nerve.