optic nerve

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Related to Optic nerves: Cranial nerves, Olfactory nerves

optic nerve:

see visionvision,
physiological sense of sight by which the form, color, size, movements, and distance of objects are perceived. Vision in Humans

The human eye functions somewhat like a camera; that is, it receives and focuses light upon a photosensitive receiver, the retina.
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Optic Nerve


(nervus opticus), the second pair of cranial nerves, along which visual stimuli received by the sensory cells of the retina are transmitted to the brain.

The optic nerve is not a typical cranial nerve in structure, but is like brain matter transported to the periphery and connected with the nuclei of the diencephalon, and through them also with the cortex of the large hemispheres. The optic nerve originates in the ganglial cells of the retina. Processes of these cells gather into the optic disk (or papilla), which is located 3 mm closer to the middle from the posterior pole of the eye. Farther on, the bundles of nerve fibers penetrate the sclera in the region of the lamina cribrosa and are surrounded by meningeal structures, forming a compact nerve trunk. Located among the bundles of fibers of the optic nerve are the central artery of the retina and the analogous vein. Together with the ophthalmic artery, the optic nerve passes into the cranial cavity through the optic canal, which is formed by a small wing of the sphenoid bone. Within the cranial cavity, the optic nerve goes from each eye toward the posterior and closer to the middle for about 1 cm, and then approaches the optic nerve of the opposite side over the sella turcica of the sphenoid bone; anterior to the hypophysis the optic chiasma is formed, where there is a crossover only of the axons of the cells of the nasal half of the retina. After the chiasma, the optic nerve continues into the optic tracts.


optic nerve

[′äp·tik ‚nərv]
The second cranial nerve; a paired sensory nerve technically consisting of three layers of special nerve cells in the retina of the eye; fibers converge to form the optic tracts.
References in periodicals archive ?
Ischemic infarction of the retrolaminar optic nerve with variable involvement of laminar and prelaminar regions characterizes both arteritic and nonarteritic anterior ION.
3) The renewed interest coincided with the recognition that an Onodi cell if unrecognized pre-operatively could lead to iatrogenic optic nerve injury.
Dehiscence of this bony structure permits exposure of the optic nerve, allowing irreversible nerve ischemia secondary to direct compression by the expansive inflammatory lesion or to ischemic infarction from thrombophlebitis or vasculitis.
Visual acuity, optic nerve size, and sensitivity to light were to be evaluated one month before stem cell therapy and three and nine months after treatment.
Optic disc drusen (ODD) are congenital and developmental anomalies characterized by calcific degeneration of the optic nerve head.
HYPOTONIA Hypotonia and optic nerve hypoplasia means Amelia has poor muscle tone - affecting movement reflexes and sight
In all 5 of the patients with MR abnormalities, increased signal was seen in the affected optic nerves on STIR sequences, while only 2 showed associated enhancement of the optic nerves.
PION is a rare condition in which there is infarction of the posterior portion of the optic nerve either following a hypotensive episode occurring intraoperatively or during a critical illness, when it is usually bilateral, or occurring spontaneously in the presence of atheromatous vascular disease or giant cell arteritis, when it typically affects just one eye.
Occasionally a physician will resort to using chemotherapy or powerful immunesuppressing medications to slow down inflammation of the optic nerves.
Since this bundle, called the optic nerve, is more accessible than are nerves inside the skull or spine, scientists have long used it as a model to investigate why other damaged nerves don't regenerate.
If a family member has glaucoma or other eye disease, you are at greater risk for glaucoma and should undergo a thorough eye exam with dilated pupils and close inspection of the optic nerve.
Doctors need to look at the optic nerve to see whether there are any changes suspicious for glaucoma.