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Topic: Optic nerve


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In the News (Wed 2 Dec 09)

  
  IX. Neurology. 5b. The Optic Nerve. Gray, Henry. 1918. Anatomy of the Human Body.
The optic nerve is peculiar in that its fibers and ganglion cells are probably third in the series of neurons from the receptors to the brain.
The orbital portion of the optic nerve is from 20 mm.
The crossed fibers of the optic nerve tend to occupy the medial side of the nerve and the uncrossed fibers the lateral side.
www.bartleby.com /107/197.html   (893 words)

  
 Optic nerve - Medical Encyclopedia   (Site not responding. Last check: 2007-10-20)
The optic nerve is the second of twelve paired cranial nerves but is usually considered to be part of the central nervous system.
The optic nerve leaves the orbit (eye) via the optic fissure, running postero-medially towards the optic chiasm where there is decussation (crossing) of fibres from the temporal fields of both eyes.
From the lateral geniculate body, fibers of the optic radiation pass to the visual cortex in the occipital lobe of the brain.
www.nursingstudy.com /encyclopedia/Optic_nerve.html   (229 words)

  
 The Optic Nerve
The optic nerve (also known as cranial nerve II) is a continuation of the axons of the ganglion cells in the retina.
Optic neuropathy is divided into anterior, which causes a pale edema of the optic disk, and posterior, in which the optic disk is not swollen and the abnormality occurs between the eyeball and the optic chiasm.
Visual field loss, caused by optic nerve damage, is measured by using a “visual field analyzer” or “perimeter.” The procedure is known as “perimetry.” Field loss due to glaucoma usually is not even measurable until 25% to 40% of the optic nerve’s axons have been destroyed.
www.tedmontgomery.com /the_eye/optcnrve.html   (1666 words)

  
 Aniridia Network - Optic Nerve Hypoplasia   (Site not responding. Last check: 2007-10-20)
When the optic nerve is underdeveloped it has fewer wires than it should have connecting the visual information recieved by the retina to the brain and this means that that not all of the visual information gets to the brain.
In a recent study of 56 people with aniridia, optic nerve hypoplasia was found in roughly 10% of patients with aniridia and may occur independently or in association with foveal hypoplasia.
Optic nerve hypoplasia is not a progressive condition, and it cannot be cured.
www.aniridia.org /conditions/optic.html   (463 words)

  
 Optic Nerve Diseases for medical students and primary care physicians
The optic nerve,(CN2), is formed by the axons of the 1.2 million ganglion cells of the retina.
Hypoplasia of the optic disc is a " smaller " disc that carries fewer axons than normal and may be associated with poor visual acuity, field defect, strabismus.....Maternal diabetes and intake of substances during the first trimester like alcohol, steroids and insulin are associated factors.
Myelinated nerve fibers: The myelinating process which is completed by the ninth month of gestation sometimes extends onto the surface of the disc or surrounding retina in a radiating fashion causing feathery white patches.
www.eyeweb.org /optic_nerve.htm   (540 words)

  
 Normal Optic Nerve   (Site not responding. Last check: 2007-10-20)
The optic nerve is composed primarily of axons from the retinal ganglion cells.
The optic nerve begins at the optic nerve head or disc (#21872, #21869) and passes through the sclera in the area of the lamina cribrosa and then extends through the orbit and optic canal to the chiasm.
Posterior to the lamina cribrosa, the optic nerve is surrounded by a three- layered meningeal sheath similar to the central nervous system which consists of a dura (optic nerve sheath), arachnoid, and pia.
insight.med.utah.edu /opatharch/onerve/normal_optic_nerve.htm   (171 words)

  
 THE MERCK MANUAL, Sec. 8, Ch. 101, Optic Nerve And Optic Pathway Disorders
In primary optic atrophy (usually due to pathology distant from the nerve head), the disk is white or grayish with sharp edges.
In secondary optic atrophy (usually due to pathology at the nerve head), the disk is dirty-white with irregular, indistinct margins and is covered by glial tissue that conceals the lamina cribrosa.
Optic atrophy is a sign of chronic optic nerve disease and is not a diagnosis in itself; its presence demands search for a cause.
www.merck.com /mrkshared/mmanual/section8/chapter101/101e.jsp   (154 words)

  
 North American Neuro-Ophthalmology Society-Committees   (Site not responding. Last check: 2007-10-20)
The optic nerve fibers are coated with myelin to help them conduct the electrical signals back to your brain.
What triggers the sudden loss of vision and optic nerve dysfunction at this time is unknown but probably occurs in individuals with a certain type of immune system.
In some cases of optic neuritis there may be more extensive involvement including the other optic nerve, the chiasm (where the two optic nerves come together), or other tissues in the brain.
www.nanosweb.org /patient_info/brochures/OpticNeuritis.htm   (1243 words)

  
 Fact Sheet Optic Nerve Atrophy
TM Optic Nerve Atrophy (ONA) is a permanent visual impairment caused by damage to the optic nerve.
The optic nerve, when examined with an ophthalmoscope, has a gray-white appearance, which may not be apparent for 4-6 weeks from time of optic nerve injury.
Optic Nerve Hypoplasia: refers to underdevelopment of the optic nerve during pregnancy.
www.blindbabies.org /factsheet_ona.htm   (988 words)

  
 Congenital Optic Nerve Anomalies   (Site not responding. Last check: 2007-10-20)
Understanding the various types of optic nerve anomalies and their clinical features is crucial to the appropriate management of this patient population, particularly given the frequency with which these types of problems present to all optometric patient populations.
Optic nerve hypoplasia is a developmental optic nerve anomaly characterized by a subnormal number of axons in the optic nerve.
Optic nerve hypoplasia is frequently associated with developmental abnormalities of anterior midline structures of the brain.
www.sunyopt.edu /ceprog/CE_CONA.shtml   (3108 words)

  
 Optic Nerve Hypoplasia   (Site not responding. Last check: 2007-10-20)
Optic nerve hypoplasia is a congenital condition in which the optic nerve has not developed properly; it is too small.
Optical nerve hypoplasia was once considered a rare condition, but now it is thought to be the most common congenital defect of the optic nerve.
Children with bilateral optic nerve hypoplasia usually present in infancy with poor vision and nystagmus, or shaking of the eyes.
www.nfb.org /fr/fr1/optic.htm   (507 words)

  
 THE MERCK MANUAL--SECOND HOME EDITION, Introduction in Ch. 235, Optic Nerve Disorders
A common cause of damage to the optic nerve is a tumor of the pituitary gland that presses on the nerve.
If the optic chiasm is damaged, both eyes lose some vision—the right eye loses vision in the right portion of its visual field, and the left eye loses vision in the left portion of its visual field.
In hemianopia, damage farther back in the optic nerve pathway (which is often the result of a stroke or a tumor) produces yet another pattern of vision loss.
www.merck.com /mmhe/sec20/ch235/ch235a.html   (365 words)

  
 Fact Sheet Optic Nerve Hypoplasia
TM Optic Nerve Hypoplasia (ONH) refers to the underdevelopment of the optic nerve during pregnancy.
The dying back of optic nerve fibers as the child develops in utero is a natural process, and ONH may be an exaggeration of that process.
Midline anomalies of the brain: septo optic dysplasia (absence of the septum pellucidum and the corpus callosum), encephaloceles, anomalies of the ventricles, anencephaly, cerebral atrophy, and rarely, tumors.
www.blindbabies.org /factsheet_onh.htm   (1277 words)

  
 Optic Atrophy: Definition, Symptoms, and Treatment - Kellogg Eye Center
The optic nerve is like a cable of more than a million tiny electrical wires, or nerve fibers each carrying a part of the visual information.
Optic atrophy means the loss of some (resulting in little visual change) or most (resulting in severe visual loss) of the nerve fibers in the optic nerve.
The optic nerve enters the back of the eye where it appears as a small disc, which your ophthalmologist can examine by looking through the pupil of your eye with a special instrument called an ophthalmoscope.
www.kellogg.umich.edu /patientcare/conditions/optic.atrophy.html   (386 words)

  
 Optic Nerve Changes   (Site not responding. Last check: 2007-10-20)
Glaucomatous damage of the optic nerve is characterized by progressive increase in cupping with loss of neuroretinal rim.
Seen on gross examination, the optic nerve is white and atrophic with a deep cupping and extreme nasal displacement of vessels(#21991).
The optic nerve tissue itself may show marked atrophy of axons with increased gliosis in the optic nerve parenchyma (#22219).
insight.med.utah.edu /opatharch/glaucoma/optic_nerve_changes.htm   (231 words)

  
 Eye Tests > Optic nerve imaging -- EyeMDLink.com
Imaging of the optic nerve head for patients who have glaucoma, or are being observed for possible glaucoma, has traditionally been completed with optic nerve photography which remains the standard of analysis.
The Glaucoma-Scope is a device that allows imaging of the optic nerve head using technology that quantitatively determines the cup/disc ratio of the optic nerve head with algorithms for monitoring change in the optic nerve from one visit to the next.
The nerve fiber layer itself is the tissue that the optic nerve is made up of and, therefore, detection of thinning of the nerve fiber layer may be correlated with risk of glaucoma or progression thereof.
www.eyemdlink.com /Test.asp?TestID=24   (371 words)

  
 Disorders of the Optic Nerve
The two optic nerves are the connections between the eyes and the rest of the brain, and all visual information passes through them.
The commonest optic neuropathy is glaucoma, characteristically a disease where damage to the nerve is produced by elevated pressure inside the eye.
Swelling of the optic nerve, called papilledema, requires urgent evaluation as tumors, bleeding, and obstruction of cerebrospinal fluid flow known as hydrocephalus must be excluded.
www.bumc.bu.edu /Dept/Content.aspx?PageID=7596&departmentid=367   (427 words)

  
 Optic nerve definition - Medical Dictionary definitions of popular medical terms
The optic nerve carries the impulses formed by the retina, the nerve layer that lines the back of the eye and senses light and creates impulses.
The cranial nerve emerge from or enter the skull (the cranium), as opposed to the spinal nerves which emerge from the vertebral column.
In sum, the optic nerve is uniquely a part of both the eye and the brain.
www.medterms.com /script/main/art.asp?articlekey=4653   (486 words)

  
 eMedicine - Optic Nerve Glioma : Article by Richard Woodcock, MD   (Site not responding. Last check: 2007-10-20)
Development of optic nerve gliomas occurs in stages, from generalized hyperplasia of glial cells in the nerve to complete disorganization with loss of neural landmarks within the nerve and nerve sheath.
The subarachnoid space (cerebrospinal fluid [CSF]) surrounding the nerve is contiguous with the CSF of the intracranial compartment.
Of optic pathway gliomas in patients with NF-1, 66% involve the intraorbital optic nerve and 10-20% are confined to the orbit, with the remainder involving the intracranial compartment.
www.emedicine.com /radio/topic486.htm   (2131 words)

  
 Optic Nerve
The optic disc is the area at the back of the eye where the optic nerve leaves, taking the visual information to the brain from the retina.
The optic disc is roughly 1.5mm in diameter.
The picture shows the area around the optic nerve head, and the stump of the optic nerve at the bottom.
www.ledc.co.uk /optic.htm   (147 words)

  
 Eye Procedures > Optic nerve sheath fenestration -- EyeMDLink.com
An optic nerve sheath fenestration is a procedure now performed almost exclusively to treat patients with pseudotumor cerebri.
An optic nerve sheath fenestration does not produce substantial lowering of intracranial pressure, and therefore, will not typically result in resolution of headaches if this is a characteristic of the syndrome.
Unfortunately, some studies suggest that an optic nerve sheath fenestration may not be a permanent panacea to the deleterious effects of pseudotumor cerebri on the optic nerve.
www.eyemdlink.com /EyeProcedure.asp?EyeProcedureID=77   (430 words)

  
 ► Optic nerve atrophy
The optic nerve may be damaged by shock, various toxic substances, radiation, and trauma.
Optic nerve atrophy may be caused by disease of the brain, such as multiple sclerosis, brain tumor, and stroke.
There are several rare forms of hereditary optic nerve atrophy that affect children and young adults.
www.umm.edu /ency/article/001622.htm   (197 words)

  
 optic nerve on Encyclopedia.com   (Site not responding. Last check: 2007-10-20)
Optic nerve sheath meningioma a diagnostic challenge: case study illustrates process of clinical judgment, evidence-based management.(No typical case)
Hannay Duffin, 7, is blind in one eye due to cancer that is attacking her optic nerve and she stands a chance of losing sight in her other eye as well.
Duffin is blind in one eye due to cancer that is attacking her optic nerve and she stands a chance of l
www.encyclopedia.com /html/X/X-opticner.asp   (507 words)

  
 Optic nerve atrophy - UMMC
Optic nerve atrophy involves tissue death of the nerve that carries the information of vision from the eye to the brain.
The optic nerve can also be damaged by shock, various toxic substances, radiation, and trauma.
There are also several rare forms of hereditary optic nerve atrophy that affect children and young adults.
www.umm.edu /ency/article/optic_nerve_atrophy_overview_001622.htm   (204 words)

  
 Optic Neuritis: Definition, Symptoms, and Treatment - Kellogg Eye Center
The optic nerve is like a cable of electrical wires or nerve fibers.
In others, optic neuritis may occur as a sign of a neurologic disease affecting nerves in various parts of the body.
Optic neuritis may be confused with other causes of poor vision.
www.kellogg.umich.edu /patientcare/conditions/optic.neuritis.html   (362 words)

  
 Optic Nerve - Eye anatomy
The optic nerve transmits electrical impulses from the retina to the brain.
When examining the back of the eye, a portion of the optic nerve called the optic disc can be seen.
The retina's sensory receptor cells of retina are absent from the optic nerve.
www.stlukeseye.com /anatomy/OpticNerve.asp   (89 words)

  
 Optic Atrophy   (Site not responding. Last check: 2007-10-20)
Optic Atrophy A Good Patient Summary Article on optic atrophy: Dysfunction of the optic nerve; may be congenital or acquired.
The milder form is autosomal dominant and has a gradual onset of deterioration in childhood but little progression thereafter; the more severe form is autosomal recessive and is present at birth or within 2 years; this form is accompanied by nystagmus.
Pale optic disk and loss of pupillary reaction are usually proportionate to the visual loss.
www.lowvision.org /optic_atrophy.htm   (118 words)

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