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	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)

	ON Hypoplasia
		In optic nerve hypoplasia, the missing nerve fibers may have represented central vision in the patient and, as a consequence, the patient may have very poor central vision and be considered legally blind (equal to or worse than 20/200 visual acuity).
		Optic nerve hypoplasia is often associated with other brain defects including absence of the septum pellucidum (a membrane that separates the front part of the lateral ventricles of the brain), agenesis of the corpus callosum (connects the left and right sides of the brain) and dysplasia of the anterior third ventricle.
		ONH may also be associated with the infant having nystagmus, where the eyes constantly move back-and-forth or the infant may have "wondering" eye movements in which the patient appears to be continuously looking around but fails to respond to visual stimuli.
	www.ohiolionseyeresearch.com /on_hypoplasia.htm (1697 words)

	Optic Nerve
		Optic nerve hypoplasia is one of the leading causes of vision loss and blindness in infants and children.
		Optic nerve hypoplasia occurs in the early stages of fetal development, when the eyes are forming.
		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.
	www.ohiolionseyeresearch.com /optic_nerve.htm (1104 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.
	ohiolionseyeresearch.com /optic_nerve.htm (1104 words)

	Aniridia Network - Optic Nerve Hypoplasia (Site not responding. Last check: 2007-10-14)
		Hypoplasia is a medical term for underdevelopment therefore optic nerve hypoplasia means underdevelopment of the optic nerve.
		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.
	www.aniridia.org /conditions/optic.html (463 words)

	Optic Nerve Hypoplasia
		Optic Nerve Hypoplasia is a congenital condition characterized by underdevelopment of the Optic Nerve and adjacent structures of the midline area of the brain.
		Many people with ONH also have malformation (dysplasia) or absence (agenesis) of other structures of the midline of the brain that are physically near the optic nerve.
		Optic Nerve Hypoplasia is associated with a host of unique characteristics that distinguish it from blindness or visual impairment due to other causes.
	www.tsbvi.edu /Outreach/seehear/summer06/onh.htm (1205 words)

	Optic nerve hypoplasia - Wikipedia, the free encyclopedia
		Optic nerve hypoplasia is a medical condition that results in underdevelopment of the optic nerves.
		Optic nerve hypoplasia can appear in one or both eyes, causing anywhere from a mild to serious visual impairment in the form of decreased visual acuity and visual fields.
		Because optic nerve hypoplasia involves the underdevelopment of structures located within the brain, the condition may also be found in conjunction with a constellation of hormonal imbalances and midline brain defects known as septo-optic dysplasia.
	en.wikipedia.org /wiki/Optic_nerve_hypoplasia (278 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)

	OPTIC NERVE HYPOPLASIA: Contact a Family - for families with disabled children: information on rare syndromes and ...
		Optic Nerve Hypoplasia (ONH) is a congenital condition (present at birth) in which there is underdevelopment of the optic nerve.
		ONH may also be associated with other conditions such as Septo-optic dysplasia due to incorrect development of the pituitary gland (see entry, Pituitary disorders).
		ONH is diagnosed on examination of the optic nerve and observation of its size and that of the nerve head.
	www.cafamily.org.uk /Direct/o16.html (701 words)

	Comparative Ophthalmology Notes: Chapter 12 - Retina, Optic Nerve, Vitreous Body (Site not responding. Last check: 2007-10-14)
		When the optic vesicle invaginates to form the optic cup there is apposition of the walls to form two layers: the outer is the future retinal epithelium and the inner is the future sensory retina.
		Myelin in the optic nerves is derived from oligodendrocytes.
		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)

	Kabat Disc
		Optic disc colobomas are often quite dramatic in appearance and once were considered to be mutilations of the disc.
		The exact mechanism responsible for optic nerve head hypoplasia is not completely understood, but the condition is believed to represent a dysplasia of the retinal ganglion cells with associated loss of the nerve fiber layer.
		Ophthalmoscopically, medullated nerve fibers appear as a white, superficial opacification of the retina that is limited to the nerve fiber layer.
	www.opt.pacificu.edu /ce/catalog/COPE7536/KabatDisc.html (4386 words)

	[No title]
		Optic atrophy, is defined as: "atrophy of the optic disc resulting from degeneration of the nerve fibers of the optic nerve and optic disc" (Dorlands 28th edition).
		However, in 30 (48.4%) of the residents with mental retardation and optic atrophy, the etiology of the brain disorder was unknown.
		Furthermore, just because the etiology of optic atrophy is known in other patients it is still possible that they are at risk for hypothalamic pituitary abnormalities, due to the relationship, anatomically, of the optic nerve, optic chiasm, and optic tracts to other structures in the brain.
	www2.umdnj.edu /forumweb/optic.htm (1238 words)

	ONH - Optic nerve hypoplasia
		The optic disc appears small and is surrounded by a ring of hypopigmentation, constituting the “double ring sign” that is the hallmark of this condition.
		Optic nerve hypoplasia, particularly the bilateral form, is associated with multiple brain malformations, including absence of the septum pellucidum, hypoplasia or agenesis of the corpus callosum, dysplasia of the anterior third ventricle, and anomalies of the hypothalamic-pituitary axis.
		Optic nerve size evaluated by magnetic resonance imaging in children with optic nerve hypoplasia, multiple pituitary hormone deficiency, isolated growth hormone deficiency, and idiopathic short stature.
	www.eye.com.ph /onh.htm (646 words)

	optic nerve - HighBeam Encyclopedia (Site not responding. Last check: 2007-10-14)
		Optic Nerve Responses of Limulus in its Natural Habitat at Night.
		A multidisciplinary approach to educating preschool children with optic nerve hypoplasia and septo-optic nerve dysplasia.
		Factor Isolated That Regenerates Nerve Fibers; Previously Unknown Molecule Spurs Regeneration in Optic Nerve.
	www.encyclopedia.com /doc/1E1-x-opticner.html (246 words)

	Optic Nerve Hypoplasia - Eye Conditions - Neville Clarence Technologies (Pty) Ltd.
		The optic nerve is the pathway for visual information to pass from the eye to the brain.
		It is felt to be the result of either failure of formation of nerve fibres early in pregnancy, or the excessive death of nerve fibres at a later stage during pregnancy.
		It is usual therefore for children with optic nerve hypoplasia to be referred to a paediatrician or investigation of these areas.
	www.nctec.co.za /eye_conditions/optic_nerve_hypoplasia.html (388 words)

	UpToDate Congenital anomalies and acquired abnormalities of the optic nerve
		Congenital optic nerve anomalies are distinguished by the optic disc and surrounding retina.
		Acquired abnormalities of the optic nerve are classified according to the reaction of the optic nerve to insult: cupping, swelling, and atrophy.
		Optic nerve aplasia typically is associated with a variety of other ocular malformations, including microphthalmia, cataract, anterior chamber angle malformation, retinal dysplasia, anterior coloboma (fissure or cleft of the iris or ciliary body), iris hypoplasia, and persistent fetal vasculature (formerly called persistent hyperplastic primary vitreous).
	patients.uptodate.com /topic.asp?file=ped_opth/6689 (429 words)

	optic-coloboma.html
		Evidence of secondary optic nerve hypoplasia was present in all eyes, and a separate chorioretinal coloboma was present in one eye.
		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.
		Atrophy of the ganglion cell and nerve fibre layers of the retina was found in all cases; optic nerve atrophy was noted in all 10 specimens in which the optic nerve was identified.
	www.indiana.edu /~pietsch/optic-coloboma.html (8213 words)

	DI in Children with Septo-Optic Dysplasia
		The third ventricle is the cavity in the brain surrounded by the thalamus, the hypothalamus, the optic chiasm, and the tubercinereum (the connection to the pituitary gland).
		The optic chiasm is where visual information from each optic nerve comes together and then separates on it’s way to the occipital lobe in the back of the brain.
		Sometime during the development of the child in the womb, the optic nerves do not fully develop, which is true for most types of congenital vision impairments.
	www.diabetesinsipidus.org /4di_septo_optic.htm (1406 words)

	Untitled (Site not responding. Last check: 2007-10-14)
		Hypoplasia of the optic nerve is a nonprogressive condition characterized by a subnormal number of optic nerve axons with normal mesodermal elements and glial supporting tissue.
		In typical cases the nerve head is small and pale, with a pale or pigmented peripapillary halo or "double ring sign".
		Protean central nervous system defects such as hydranencephaly or anencephaly or more focal lesions compatible with continued development of the patient may accompany optic nerve hypoplasia, but unilateral or bilateral optic nerve hypoplasia may be seen without any concomitant defects.
	www.members.aol.com /scottolitsky/ONH.htm (161 words)

	sod-medline.html
		Orbital and cranial computerized tomographic scanning and magnetic resonance imaging demonstrated bilateral microphthalmos and presumed retinal dysplasia, hypoplasia of the optic nerves and chiasm, agenesis of the septum pellucidum, thinning of corpus callosum, and a normal pituitary infundibulum.
		Unilateral hypoplasia of the optic nerve was found in 7 cases, bilateral hypoplasia in 11.
		Optic nerve hypoplasia is sometimes associated with agenesis of the septum pellucidum, commonly known as septo-optic dysplasia, and/or hypopituitarism.
	www.indiana.edu /~pietsch/sod-medline.html (4406 words)

	The Savant Academy
		ONH blindness is caused by factors which are probably in place by the fifth or sixth week of pregnancy.
		ONH is on the increase, and is today considered the most common single cause of congenital blindness in the industrialized world.
		ONH behaviors are sometimes puzzling, and parents are never quite sure what might set their child off or to what the child is responding.
	www.savantacademy.org /onhqa.php (1210 words)

	Handbook of Ocular Disease Management - Optic Nerve Head Hypoplasia
		Because optic nerve head hypoplasia is congenital, it is typically diagnosed in younger patients at their initial eye examination.
		Underdevelopment of the optic nerve results, and the posterior scleral foramen "fills in" with connective and scleral tissues.
		ONH hypoplasia may be part of larger clinical syndromes such as septo-optic dysplasia, which is marked by short stature, congenital nystagmus and a hypoplastic disc.
	www.revoptom.com /handbook/sect6i.htm (528 words)

	Optic Nerve Hypoplasia and Nystagmus
		ONH is present when the optic nerves fail to develop fully during early pregnancy (7-8 weeks gestation) for unknown reasons.
		Therefore, the brain adapts to the small optic nerves, and a child with ONH may have dramatically better vision at age 5 than they had at age 1.
		However, this also means that once a child reaches age 8 or so, even if new optic nerves could be generated by some miraculous procedure, their brain would not process visual input correctly for normal sight.
	www.mindspring.com /~doumas/vision.htm (1619 words)

	Optic atrophy (Site not responding. Last check: 2007-10-14)
		Visual loss as a result of pressure against the optic nerve may be restored if the cause is identified and treated early.
		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.
		Ophthalmologically, the nerve head appears unusually small, and is surrounded by a white "halo" of scleral tissue showing through.
	www.spedex.com /resource/documents/veb/optic_atrophy.html (384 words)

	EyeRounds.org: Optic Nerve Hypoplasia
		The veins are 120-150 microns in diameter; thus, this optic nerve is less than 1 mm in diameter (average optic nerves are ~1.5 mm in diameter with ~1.2 million nerve fibers).
		Additionally, the left optic nerve is severly hypoplastic with only a stump of nerve tissue with crowded retinal vessels exiting the nerve.
		The patient was informed that: she was born with optic nerve hypoplasia, her vision was affected because of this, and her cataracts were not visually significant.
	webeye.ophth.uiowa.edu /eyeforum/cases/case10.htm (583 words)

	What is Optic Nerve Hypoplasia?
		Optic nerve hypoplasia, sometimes called septo-optic dysplasia or deMorsier’s syndrome, is the under-development or absence of the optic nerve combined with possible brain and endocrine abnormalities.
		ONH is the SINGLE leading cause of blindness and visual impairment in children.
		In some instances ONH includes agenesis (absence) or abnormal development of the corpus callosum and septum pellucidum.
	www.onesmallvoicefoundation.org /whatisonh.html (395 words)

	eMedicine - Aniridia in the Newborn : Article by Sophie Bakri, MD (Site not responding. Last check: 2007-10-14)
		Foveal and optic nerve hypoplasia are often present, causing a reduction in visual acuity and congenital sensory nystagmus.
		Poor vision in infancy often is due to foveal or optic nerve hypoplasia and secondary nystagmus.
		Because the retina is derived from neuroectoderm, as are the iris epithelium and musculature, foveal hypoplasia often is associated with aniridia.
	www.emedicine.com /oph/topic317.htm (3091 words)

	OptiGen - New Genetic Test for Collie Eye Anomaly / Choroidal Hypoplasia - CEA/CH Test - canine genetic testing
		The lesion appears as an area lateral (temporal) to the optic disc with reduction or absence of pigment so that the underlying vessels of the choroid are seen.
		Colobomas are seen at and near the optic nerve head as outpouchings or “pits” in the eye tissue layers.
		The result is the percentage of collies affected with choroidal hypoplasia remains high, but the severe grades of the disease (colobomas and retinal detachments) have decreased due to this conscientious breeding.
	www.optigen.com /opt9_test_cea_ch.html (2328 words)

	Sheryl's Originals Primitive Graphics And Web Site Design For The Serious Crafter
		hypoplasia means underdevelopment of a body structure, so optic nerve hypoplasia means underdevlopment of the optic nerve
		ONH is non progressive, meaning it doesn't get any worse than what it already is, and the optic nerve is 25% the normal size (it is smaller)
		In most cases the mom was healthy, it was a normal pregnancy, was seen by OB regularly, was on prenatal vitamins and they have no idea as to why it happened.
	www.sherylsgraphics.com /onh.html (496 words)

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