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	Dr. Koop - Ischemic Optic Neuropathy- Health Encyclopedia and Reference
		Optic neuropathy describes abnormalities of the optic nerve that occur as a result of ischemia, toxins, vascular and blood pressure abnormalities, and compression within the orbit.
		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 globe and the optic chiasm.
		Is it an abnormality of the optic nerve?
	www.drkoop.com /encyclopedia/93/411.html (632 words)

	Optic Nerve
		Optic nerve hypoplasia is one of the leading causes of vision loss and blindness in infants and children.
		Recent evidence suggests that ganglion cell axons, that make-up the optic nerve, are not able to grow through the optic nerve head because certain chemical messengers are not present for directional growth from the eye to the brain.
		Drusen of the optic nerve are little whitish or translucent bodies of various size that are in the nonmyelinated part of the optic nerve head.
	www.ohiolionseyeresearch.com /optic_nerve.htm (1104 words)

	Comparative Ophthalmology Notes: Chapter 12 - Retina, Optic Nerve, Vitreous Body (Site not responding. Last check: 2007-10-22)
		Myelin in the optic nerves is derived from oligodendrocytes.
		Optic disk is non-myelinated and horizontally oval or sometimes round, often with indistinct borders; the tapetum usually ends at or around the dorsal border.
		In the collie, however, the nerve (disk) appears colobomatous, but often is near normal further into the orbit; the colobomatous appearance is due to scleral ectasia in the region of the optic disk causing distortion of the nerve as it leaves the eye.
	www.vetmed.ucdavis.edu /courses/vet_eyes/conotes/con_chapter_12.html (9493 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.
		Ischemic anterior optic neuropathy usually causes a loss of vision that may be sudden or occur over several days; whereas, ischemic posterior optic neuropathy is uncommon, and the diagnosis depends largely upon exclusion of other causes, chiefly stroke and brain tumor.
	www.tedmontgomery.com /the_eye/optcnrve.html (1666 words)

	Ophthalmology Management
		Once the edge of the optic disk has been identified, it is important to measure the size of the optic disk.
		Thus, in a disk that is small even a slight increase in size of the cup may have substantial implication; whereas, in a very large disk, a very large cup may be normal.
		Thus progressive damage to the optic disk and the retinal nerve fiber layer alone is sufficient for the diagnosis of glaucoma and the initiation of treatment.
	www.ophthalmologymanagement.com /article.aspx?article=86399 (1448 words)

	Optic atrophy (Site not responding. Last check: 2007-10-22)
		Pale optic disk and loss of pupillary reaction are usually proportionate to the visual loss.
		NOTE: Optic nerve hypoplasia should not be confused with optic atrophy.
		Optic nerve hypoplasia is an undeveloped optic nerve due to a neurological insult early in the prenatal developmental period; the optic nerve has started to develop, but regresses.
	www.tsbvi.edu /Education/anomalies/optic_atrophy.htm (376 words)

	Magneto-optic disk apparatus (Site not responding. Last check: 2007-10-22)
		A magneto-optic disk apparatus is disclosed which can reproduce data well from a magneto-optic disk on which the data are reproduced in a high density with an increased line density.
		With the magneto-optic disk apparatus, the sample servo method is used as the servo method for the magneto-optic disk and even though the disk is recorded in a high density with an increased line density, reproduction of clocks can be performed stably.
		Preferably, the magneto-optic disk is divided radially into a plurality of zones and the data are recorded such that the line densities of the zones may be substantially equal to one another.
	www.emergenthomestore.com /techcat/bottle_stopper_with_seal/magneto-optic_disk.html (4164 words)

	American Glaucoma Society
		The circular optic disk border is visualized as the junction between the nerve head and the surrounding retina.
		The optic nerve is primarily composed of the axons (the retinal nerve fibers) from the retinal ganglion cells and acts as the connection between the retina and the brain.
		Glaucomatous optic neuropathy in moderate stages is easily recognized with ophthalmoscopy by the presence of cupping, or enlargement of the central cup on the optic nerve, especially if the cupping is focal within the nerve or asymmetrical between the two eyes.
	www.glaucomaweb.org /displaycommon.cfm?an=1&subarticlenbr=12 (4694 words)

	* Disk - (Disease): Definition
		One of the most common types of back surgery is disk removal (disk ectomy), the removal of an intervertebral disk, the flexible plate that connects any two adjacent vertebrae in the spine...
		Degenerative disk disease means wear and tear changes in the disk. Nearly everyone has signs of degeneration of lumbar disks after age 40, although some people show evidence of changes much earlier...
		Swelling around the optic disk, the area where the optic nerve (the nerve that carries messages from the eye to the brain) enters the eyeball.
	en.mimi.hu /disease/disk.html (667 words)

	ENLmedical.com: Conditions And Concerns: Medical Encyclopedia: Optic glioma
		Optic gliomas cause symptoms by invasion (pressure) and displacement (destruction) of normal optic nerve tissue.
		Optic glioma and other astrocytomas are rare (however, astrocytomas in general are the most common primary brain tumors in adults).
		There may be optic disc or nerve head changes in the optic nerve, including papilledema (swelling of the nerve), or paleness and atrophy of the optic disk.
	www.enlmedical.com /article/001024.htm (490 words)

	Glaucoma
		The optic nerve is like a giant "electric cable," containing more than a million nerve fibers, which carries images from the retina to the brain.
		The optic disk is the area where all the nerve fibers come together at the back of the eye before exiting the eyeball.
		An optic disk that has been affected by glaucoma appears indented, or excavated, as if someone scooped out part of the center of the disk, a condition known as "cupping." The normal contour and colour of the disk may be affected by the loss of nerve fibers.
	www.innvista.com /health/ailments/eyeail/glaucoma.htm (2095 words)

	Optic Disk (Site not responding. Last check: 2007-10-22)
		Four cases of normal-tension glaucoma with disk hemorrhage combined with branch retinal vein occlusion in the contralateral eye.
		Optic nerve oxygen tension: the effects of timolol and dorzolamide.
		Optic disc excavation in the atrophic stage of Leber's hereditary optic neuropathy: comparison with normal tension glaucoma.
	www.find-health-articles.com /Cate-Optic-Disk.htm (525 words)

	Answer to Ophthaproblem
		The optic nerve swells for a variety of reasons; swelling is manifest in a funduscopic examination as optic disk edema.
		Optic disk drusen account for 75% of clinical cases of pseudopapilledema3 and occur in up to 2% of the general population.
		Optic disk drusen, acellular structures that are typically calcified, round, yellow, and various sizes, tend to be located in the nasal aspect of the preliminary portion of the optic nerve.
	www.cfpc.ca /cfp/2002/May/vol48-may-clinical-2.asp?stype=advanced& (610 words)

	Optic Disk (Site not responding. Last check: 2007-10-22)
		It has a depression in its center called the "fovea centralis." This depression is the region of the retina that produces the sharpest vision.
		Toward the center of the fovea centralis is an area called the "optic disk." The nerve fibers leave the eye at this point to become parts of the optic nerve.
		A central artery and vein also pass through at the optic disk to supply blood to the cells of the inner layer of the eye.
	www.innerbody.com /text/nerv112.html (94 words)

	Optic Neuritis: Optic Nerve Disorders: Merck Manual Home Edition
		Optic neuritis may be caused by a viral infection (especially in children), vaccination, meningitis, syphilis, certain autoimmune diseases such as multiple sclerosis, and intraocular inflammation (uveitis (see Uveitis).
		Optic neuritis causes vision loss, which may be mild or severe and may occur in one or both eyes.
		Diagnosis involves examination of the reactions of the pupils and observing the back of the eyes with an ophthalmoscope; the optic disk (the head of the optic nerve at the back of the eye) may appear swollen.
	www.merck.com /mrkshared/mmanual_home2/sec20/ch235/ch235c.jsp (236 words)

	optic-coloboma.html
		CONCLUSION: Central visual acuity in children born with colobomas involving the optic nerve correlates with the development of normal foveal anatomy, regardless of the size of the coloboma, the color of the optic nerve, or the presence of subfoveal pigmentary changes.
		The retinal vascular anomalies extended from the optic disk to the temporal periphery.
		Optic nerve hypoplasia and colobomas of the optic disc are the main visually significant disorders; however, the Morning Glory disc anomaly and Aicardi's syndrome may also be associated with visual impairment.
	www.indiana.edu /~pietsch/optic-coloboma.html (8213 words)

	Genetic Algorithm Based Detection of Optic Disk in Retinal Images
		The location of the optic disc is of critical importance in retinal image analysis and is required as a prerequisite stage of exudates detection, blood vessel tracking and segmentation.
		The optic disc is the entrance region of blood vessels and optic nerves to the retina and often serves as references of other features.
		As the diameter of optic disc is in the range of 65~100 pixels [3] in the retinal image of 512 x 512 pixels, the initial contours are generated within this limit from the optic disc center.
	www.acadjournal.com /2006/V17/part6/p5 (1672 words)

	Olympus Microscopy Resource Center: Anatomy of the Microscope - Brightfield Microscopy Digital Image Gallery - Optic ...
		Vital to this interactive communication are the optic nerves, which carry nerve impulses from the retinas to the thalamus and other parts of the brain.
		The optic nerve, which arises from the junction of visual nerve fibers in the optic disk located in the back of the eyeball, is the second of twelve distinct paired cranial nerves.
		It is at this X-shaped structure that the optic nerve from each eye meets, part of the fibers of each crossing over to the other side of the brain and the other half maintaining their original orientation.
	www.olympusmicro.com /primer/anatomy/brightfieldgallery/opticnerve20xsmall.html (344 words)

	Optic Glioma - Health Encyclopedia
		Most optic gliomas are slow-growing and non-cancerous (benign) and occur in children, almost always before age 20.
		The symptoms are due to the tumor growing and pressing on the optic nerve and nearby structures.
		There may be changes in the optic nerve, including swelling or scarring of the nerve, or paleness and atrophy of the optic disk.
	www.nbc4.tv /encyclopedia/6861395/detail.html (833 words)

	Disappearing Dot - Science Tricks - Surfing Scientist - The Lab
		The optic disk is the bright area in the photo of the retina above.
		Because the optic nerve itself is not sensitive to light, the optic disk is a blind spot.
		Now the optic disk is very close to another important part of your retina called the fovea.
	www.abc.net.au /science/surfingscientist/disappearingdot.htm (559 words)

	Papillitis
		Papillitis, also known as optic neuritis, is characterized by inflammation and deterioration of the portion of the optic nerve known as the optic disk.
		Also referred to as the "blind spot," the optic disk (optic papilla) is that portion of the optic nerve that enters the eye and joins with the nerve-rich membrane lining the eye (retina).
		The optic nerves are the pair of nerves (second cranial nerves) that transmit impulses from the retina to the brain.
	www.webmd.com /eye-health/Papillitis (589 words)

	optic disk
		This is much less than the 130 million or so photoreceptor cells in the retina and indicates that quite a lot of preprocessing takes place before signals are sent along the optic nerve to the brain.
		No photoreceptors occur in the region where the optic nerve leaves the eye, resulting in a blind spot.
		A common cause of damage to the optic nerve is glaucoma.
	www.daviddarling.info /encyclopedia/O/optic_nerve.html (164 words)

	Optic neuritis - MayoClinic.com (Site not responding. Last check: 2007-10-22)
		Optic neuritis is due to inflammation of the optic nerve, which transmits light and visual images from the retina to the brain.
		The optic disk is where all of the nerve fibers come together at the back of the eye.
		The optic nerve is a bundle of nerve fibers that serves as the...
	www.mayoclinic.com /invoke.cfm?id=AN00227 (322 words)

	Septo Optic Dysplasia
		In addition to underdevelopment (hypoplasia) of the optic nerves (i.e., the pair of nerves [second cranial nerves] that transmit "signals" from the nerve-rich membranes lining the eyes (retina) to the brain), the optic disk may be one third to one half its normal size in one (unilateral) or both (bilateral) eyes.
		Also referred to as the "blind spot," the optic disk is that portion of the optic nerve that enters the eye and joins with the retina.
		In many cases of Septo-Optic Dysplasia, ophthalmoscopy may reveal that the optic disk is approximately one half or one third the normal size, has an abnormal double-rim or cuff-like appearance, and exhibits other abnormalities (e.g., pale nerve tissue, large retinal vessels).
	hw.healthdialog.com /kbase/nord/nord496.htm (3099 words)

	Morphogenesis of the Lateral Geniculate Nucleus
		The transition between the 6- and 4-layer regions occurs at the position of the optic disk (the blind spot caused by the exit of the optic nerve from the eye).
		The not shown 2 magnocelullar layers run parallel to the 4 parvocellular ones and are not interrupted by the optic disk.
		The optic disk, being a perturbation, however small, causes the system to switch to its most stable state: the 4-layer pattern.
	www.ks.uiuc.edu /Research/Neural/morphogenesis.html (926 words)

	Webvision: Regeneration1
		Letters in lower case indicate a vein in the optic nerve (a), "neurilema" in the sciatic nerve graft (b), fibers that might correspond to RGC axons regenerated in the sciatic nerve graft (c).
		In brief, the potential for regeneration of optic axons after being damaged was first indicated by studying hamsters in which the optic nerve was cut and a peripheral nerve graft placed in association with the retinal optic fiber layer (So and Aguayo, 1985) (Fig 3).
		Optic axons grew into this nerve graft and studies in cat, in this instance, showed that the major classes characterized both anatomically and physiologically, contribute to this regenerative growth (Fukuda et al., 1998).
	webvision.med.utah.edu /Regeneration1.html (13812 words)

	Untitled Document
		This results in defects of the sclera, choroid, optic disk, retina and blood vessels of the retina.
		In CEA, colobomas are depressions or excavations in the back of the eye and may involve the optic disk and/or the area around the optic disk.
		Large optic disc colobomas can cause retinal detachment because the large "hole" in the back of the eye leads to accumulation of fluid behind the retina and pushes off the retina.
	www.vmdb.org /collie%20eye.html (569 words)

	AION
		Reduced flow of blood to the anterior optic nerve results in ischemia (tissue damage) and infarction (tissue death), as occurs with a brain stroke, but the cause is not usually a thrombus (attached blood clot) or embolus (traveling blood clot) but rather a period of hypotension (low blood pressure).
		Thus a cup to disk ratio of 0.4 means that the hole is 2/5 the width of the entire disk.
		For example, Lee et al (Atypical features prompting neuroimaging in acute optic neuropathy in adults) reported on several cases which were initially diagnosed as as optic neuritis or NAION but in which the problem was subsequently found to stem from intracranial lesions.
	personal.ecu.edu /wuenschk/AION.htm (3103 words)

	InteliHealth:
		Retrobulbar neuritis is a form of optic neuritis in which the optic nerve, which is at the back of the eye, becomes inflamed.
		This is where the optic nerve fibers concentrate before exiting the eye to extend back toward the brain.
		In the early stages of retrobulbar neuritis, the optic disk appears normal.
	www.intelihealth.com /IH/ihtIH/WSIHW000/9339/10461.html (694 words)

	Locating the Optic Disk in Retinal Images
		Method: The location of the optic disk is an important issue in retinal image analysis as it is a significant landmark feature and its diameter is usually used as a reference length for measuring distances and sizes.
		We have proposed a method to identify EXs automatically [1] that also partially extracts the optic disk as candidate EX regions due to colour similarity between the EXs and optic disk.
		In this paper, we report on the selection of candidate optic disk regions amongst the EXs, boundary analysis, and optic disk centre and radius estimation using minimum boundary arc lengths.
	www.cs.bris.ac.uk /Publications/pub_info.jsp?id=1000555 (339 words)

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