The optic nerve in its development and structure of a brain region which is submitted to the periphery. It consists of processes of third nerve cells of the retina. These processes and form the optic nerve.
On the back of the eye can see part of the intraocular optic nerve - the optic disc. In the area of the disk processes of ganglion cells come together, forming a disk, and then turned 90 degrees. After that, the optic nerve away from the eyeball, passes through a bony canal in the skull and the base of the skull forms a chiasma (crossing of the optic nerves).
Then the nerve divides into three parts, which end in the subcortical centers of which is the primary processing of visual information and the formation of pupillary reaction. From subcortical centers of the central visual path begins (visual radiance Grazioli), which ends in the cortex of the occipital lobes of the brain.
Congenital malformations of the optic nerve:
Hypoplasia of the optic nerve. Hypoplasia or underdevelopment of the optic nerve is a congenital anomaly in which the observed reduction in size of the optic nerve disc. Abnormal disc can be half or one-third less than normal. Preservation of visual function in this case depends on the degree of reduction of the optic nerve and preservation of fibers extending from the central, best-sighted, divisions of the retina. By extreme hypoplasia may be aplasia or absence of optic nerves.
Hamartoma. (From the Greek word hamartia - error). On a normal location of the optic nerve in this case is tumor-like formations, whose cells do not function as the optic nerve. Restore the function of impossible.
Coloboma. Coloboma is a defect of the optic nerve tissue. In the fundus are deepening in the optic nerve. Perhaps a combination of coloboma of the optic nerve colobomas of the iris and choroid. Coloboma often is hereditary. Impaired vision depends on the size of the defect. Sometimes there is a partial coloboma of the optic nerve, called the pit of the optic nerve. At the same time on the temporal side of the optic nerve revealed a small dip.
This condition is often not reflected in visual function, but if the pit of the optic nerve are accompanied by anomalies of the vessels in the fovea, the function of view can be greatly compromised due to swelling and damage to the central part of the retina.
Myelinated fibers of the optic nerve. Nerve fibers are processes of nerve cells that seem to be wrapped in a shell of other cells. This shell is called myelin. Sometimes there is a condition where the myelin sheath wraps not only optic nerve fibers, and fibers that begin in the retina. These fibers appear in the fundus as the language creeps from the optic nerve to the retina. On the function of myelinated fibers are often not recognized, but sometimes if they grow large degree, they may cover part of the retinal tissue and increase the "blind spot" corresponding to the optic disc.
Twice the optic disc. When this anomaly in the fundus revealed two of the optic nerve. Sometimes both can be reduced in size and underdeveloped, but most of them undeveloped, while the second carries out its function.
Visual psevdonevrit. Visual or polyneuritis giperglioz this proliferation of connective tissue in the optic disc. Usually this is accompanied by farsightedness (hyperopia). The fundus revealed expansion of the boundaries of the optic nerve, the absence of its normal groove.
Congenital optic atrophy. Complete congenital atrophy is accompanied by a lack of vision. In the fundus are reduced, pale gray optic disc. Eye movement plavayuschie.Vrozhdennaya optic atrophy may be partial, in this case, vision saved the extent that the degree of atrophy.
Drusen of the optic nerve. In this congenital abnormality of the optic nerve tissue in the present round grayish-yellow of education that are in the depths of the optic disc or in favor of its borders. The cause of drusen has not been established. This anomaly has a hereditary nature. When compression of drusen of optic nerve fibers of the function can be broken.
Prepapillar membrane. Prepapillyarnaya membrane is the formation of a film that can be thin or thick, over the optic disc. It is believed that this anomaly occurs in violation of the formation of the vitreous body. Typically, the state of prepapillyarnaya membrane is not reflected.