The nerve fibers forming the

optic nerve In neuroanatomy, the optic nerve, also known as the second cranial nerve, cranial nerve II, or simply CN II, is a paired cranial nerve that transmits visual information from the retina to the brain. In humans, the optic nerve is derived fro ...

exit the eye posteriorly through a hole in the sclera that is occupied by a mesh-like structure called the lamina cribrosa. It is formed by a multilayered network of collagen fibers that insert into the scleral canal wall. The nerve fibers that comprise the optic nerve run through pores formed by these collagen beams. In humans, a

central retinal artery The central retinal artery (retinal artery) branches off the ophthalmic artery, running inferior to the optic nerve within its dural sheath to the eyeball. Structure The central retinal artery pierces the eyeball close to the optic nerve, sendin ...

is located slightly off-center in nasal direction. The lamina cribrosa is thought to help support the retinal ganglion cell axons as they traverse the scleral canal. Being structurally weaker than the much thicker and denser sclera, the lamina cribrosa is more sensitive to changes in the intraocular pressure and tends to react to increased pressure through posterior displacement. This is thought to be one of the causes of nerve damage in

glaucoma Glaucoma is a group of eye diseases that result in damage to the optic nerve (or retina) and cause vision loss. The most common type is open-angle (wide angle, chronic simple) glaucoma, in which the drainage angle for fluid within the eye rem ...

, as the displacement of the lamina cribrosa causes the pores to deform and pinch the traversing nerve fibers and blood vessels.

References

{{Authority control Human eye anatomy