Structure and Function of the Optic Nerve
- The optic nerve is a myelinated tract of the central nervous system derived from optic stalks during embryonic development.
- It is covered with myelin produced by oligodendrocytes and encased within the meninges.
- The optic nerve contains between 770,000 and 1.7 million nerve fibers derived from retinal ganglion cells.
- The optic nerve transmits visual information, including brightness perception, color perception, and contrast.
- It conducts visual impulses responsible for the light reflex and the accommodation reflex.
- The light reflex refers to the constriction of both pupils when light is shone into either eye.
- The accommodation reflex refers to the swelling of the lens when looking at a near object.
- The absence of photoreceptors in the area where the optic nerve leaves the eye results in the blind spot.
Clinical Significance of Optic Nerve Damage
- Damage to the optic nerve causes permanent and potentially severe loss of vision.
- The type of visual field loss depends on the location of the damage in relation to the optic chiasm.
- Anterior damage causes loss of vision in the same side eye, while damage at the optic chiasm causes lateral vision loss or bitemporal hemianopsia.
- Damage to the optic tract causes loss of the entire visual field from the opposite side of the damage.
- Optic nerve injuries can result from congenital problems, glaucoma, trauma, toxicity, inflammation, ischemia, infection, or compression.
Optic Nerve Diseases
- Glaucoma is a group of diseases that cause optic neuropathy and peripheral vision loss due to the loss of retinal ganglion cells.
- Optic neuritis is inflammation of the optic nerve and is associated with various diseases.
- Anterior ischemic optic neuropathy is a condition that affects individuals older than 50 years and causes optic nerve damage.
- Congenital or inheritable problems like Leber's hereditary optic neuropathy can lead to optic nerve damage.
- Injury to the optic nerve can also result from trauma, toxicity, inflammation, ischemia, infection, or compression.
- Multiple sclerosis can cause varying vision loss and eye pain.
- Optic nerve hypoplasia leads to underdeveloped optic nerves and little to no vision in the affected eye.
- Tumors, especially those of the pituitary gland, can put pressure on the optic nerve and cause visual loss.
- Trauma, both direct and indirect, can cause serious injury to the optic nerve.
Anatomy of the Optic Nerve
- The optic nerve leaves the eye via the optic canal and runs towards the optic chiasm.
- The proportion of decussating fibers varies between species and is related to binocular vision.
- Most axons of the optic nerve terminate in the lateral geniculate nucleus, while others terminate in the pretectal area and suprachiasmatic nucleus.
- The diameter of the optic nerve increases from the eye to the orbit to the cranial space.
- The optic nerve can be divided into four parts: optic head, orbital part, intracanicular part, and cranial part.
Diagnosis and Treatment of Optic Nerve Diseases
- Ophthalmologists and optometrists can detect and diagnose some optic nerve diseases.
- Neuro-ophthalmologists are best suited to diagnose and treat diseases of the optic nerve.
- The International Foundation for Optic Nerve Diseases (IFOND) sponsors research and provides information on various optic nerve disorders.
This article includes a list of general references, but it lacks sufficient corresponding inline citations. (June 2018) |
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 from optic stalks during the seventh week of development and is composed of retinal ganglion cell axons and glial cells; it extends from the optic disc to the optic chiasma and continues as the optic tract to the lateral geniculate nucleus, pretectal nuclei, and superior colliculus.
| Optic nerve | |
|---|---|
 The left optic nerve and the optic tracts. | |
| Details | |
| Innervates | Vision |
| Identifiers | |
| Latin | nervus opticus |
| MeSH | D009900 |
| NeuroNames | 289 |
| TA98 | A14.2.01.006 A15.2.04.024 |
| TA2 | 6183 |
| FMA | 50863 |
| Anatomical terms of neuroanatomy | |
optic nerve (plural optic nerves)
