| optic glioma | <oncology, tumour> A tumour of the optic nerve that can result in blindness to the pressure and destruction (caused by the tumour) of the optic nerve. There is an association between optic gliomas and neurofibromatosis. Surgical excision or radiation therapy is the general coarse of treatment. (27 Sep 1997) |
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| optic groove | The groove on the upper surface of the sphenoid bone running transversely between the optic canals bounded anteriorly by the sphenoidal limbus and posteriorly by the tuberculum sellae; forms in relationship to the optic chiasm. Synonym: sulcus prechiasmatis, chiasmatic sulcus, optic groove, prechiasmatic sulcus. (05 Mar 2000) |
| optic layer | A layer of white matter interspersed with nerve-cell bodies, immediately below the superficial gray layer of the superior colliculus, composed of myelinated fibres originating in the retina and striate cortex, the inner layer of the retina, consisting of the fibres originating from the cells of the ganglionic layer of optic nerve; in their further course these fibres combine to form the optic nerve or optic tract. Synonym: stratum opticum. (05 Mar 2000) |
| optic lobe | In invertebrate zoology, a lateral lobe of the forebrain in certain arthropods. In vertebrate zoology, either of the corpora bigemina of lower vertebrates. (12 Dec 1998) |
| optic nerve | <anatomy, nerve> The optic nerve. The nerve carrying impulses for the sense of sight. Projection from the vertebrate retina to the midbrain. Embryologically, a CNS tract rather than a peripheral nerve. Popular experimental preparation for studies of regeneration of retino tectal projections in lower vertebrates and also for studies of glial cell lineage in CNS. Synonym: cranial nerve II. (18 Nov 1997) |
| optic nerve diseases | Diseases of the optic nerve. (12 Dec 1998) |
| optic nerve drusen | Basophilic, calcareous, laminated acellular bodies within the optic nerve anterior to the scleral lamina cribrosa. (05 Mar 2000) |
| optic nerve glioma | <radiology> F = M, child / young adult (75% less than 10 yrs, 90% less than 20 yrs), fusiform, isodense mass, with or without enhancement, rarely calcified associated with neurofibromatosis Cf: optic nerve meningioma (12 Dec 1998) |
| optic nerve head | The portion of the optic nerve seen in the fundus with the ophthalmoscope. It is formed by the meeting of all the retinal ganglion cell axons as they enter the optic nerve. Because the retina at the optic disk has no photoreceptors there is a corresponding blind spot in the visual field. (12 Dec 1998) |
| optic nerve hypoplasia | Congenitally small optic disk resulting from failure of development of retinal ganglion cells, with a reduced number of axons; visual impairment may be marked. See: de Morsier's syndrome. (05 Mar 2000) |
| optic nerve meningioma | <radiology> Female (80%), middle age, (24% occur before 10 yrs, but are associated with neurofibromatosis), tubular, hyperdense mass, intense tramtrack enhancement, ** Cf: optic nerve glioma (12 Dec 1998) |
| optic nerve sheath decompression | A venting of the optic nerve sheath into the retrobulbar space, by slitting or by fenestrating the sheath. See: optic nerve sheath fenestration. (05 Mar 2000) |
| optic nerve sheath fenestration | The cutting of a window in the dura of the optic nerve sheath to relieve papilledema and prevent further loss of optic nerve fibres. (05 Mar 2000) |
| optic neuritis | <pathology> Inflammation of the optic nerve. This may occur secondary to a wide variety of causes: multiple sclerosis, posterior uveitis, vascular lesions of the optic nerve (interruption of blood supply to the optic nerve), temporal arteritis, central retinal artery occlusion, methyl alcohol poisoning, drug side effects and acute demyelinative disease of the optic nerves (destruction of optic nerve sheath). (27 Sep 1997) |
| optic neuroma | A benign tumour of the optic nerve. (12 Dec 1998) |
| drusen of the optic nerve head | Basophilic, laminated, calcareous acellular masses that resemble crystals within the nerve head, anterior to the lamina cribrosa, that may simulate papilledema and/or cause visual field defects. Synonym: intrapapillary drusen. (05 Mar 2000) |
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| dural sheath of optic nerve | <anatomy, nerve> The outer sheath around the optic nerve, continuous with the dura mater. Synonym: vagina externa nervi optici, dural sheath of optic nerve. (05 Mar 2000) |
| internal sheath of optic nerve | <anatomy, nerve> The innermost sheath around the optic nerve, continuous with the leptomeninges (pia-arachnoid) and including a cerebrospinal fluid-filled intervaginal space, continuous with the subarachnoid space. Synonym: vagina interna nervi optici. (05 Mar 2000) |
| intersheath spaces of optic nerve | <anatomy, nerve> The spaces within the internal sheath of the optic nerve, between the arachnoidal and pial layers, filled with cerebrospinal fluid and continuous with the subarachnoid space. Synonym: spatia intervaginalia nervi optici, intersheath spaces of optic nerve, Schwalbe's spaces. (05 Mar 2000) |
| intervaginal space of optic nerve | <anatomy, nerve> The spaces within the internal sheath of the optic nerve, between the arachnoidal and pial layers, filled with cerebrospinal fluid and continuous with the subarachnoid space. Synonym: spatia intervaginalia nervi optici, intersheath spaces of optic nerve, Schwalbe's spaces. (05 Mar 2000) |
| intracanicular part of optic nerve | <anatomy, nerve> The part of the optic nerve lying within the optic canal. Synonym: pars intracanaliculus nervi optici. (05 Mar 2000) |
| intracranial part of optic nerve | <anatomy, nerve> The portion of the optic nerve between the optic canal and the optic chiasm. Synonym: pars intracranialis nervi optici. (05 Mar 2000) |
| intralaminar part of optic nerve | <anatomy, nerve> The portion of the optic nerve as it passes through the lamina cribrosa of the sclera. Synonym: pars intralaminaris nervi optici. (05 Mar 2000) |
| intraocular part of optic nerve | <anatomy, nerve> The part of the optic nerve within the eye; it is divided into intralaminar, postlaminar, and prelaminar parts. Synonym: pars intraocularis nervi optici. (05 Mar 2000) |
| ischemic optic neuropathy | Optic nerve neuropathy secondary to hypoperfusion of the low pressure posterior ciliary arteries supplying the optic nerve head (nonarteritic) or to temporal arteritis (arteritic). (05 Mar 2000) |
| orbital part of optic nerve | <anatomy, nerve> The part of the optic nerve between the eye and the optic canal. Synonym: pars orbitalis nervi optici. (05 Mar 2000) |
| excavation of optic disc | The normally occurring depression or pit in the centre of the optic disc. Synonym: excavatio disci, depression of optic disk, excavatio papillae, physiologic cup, physiologic excavation. (05 Mar 2000) |
| external sheath of optic nerve | <anatomy, nerve> The outer sheath around the optic nerve, continuous with the dura mater. Synonym: vagina externa nervi optici, dural sheath of optic nerve. (05 Mar 2000) |
| lateral root of optic tract | The larger division of the posterior end of the optic tract that terminates in the lateral geniculate body. Synonym: radix lateralis tractus optici. (05 Mar 2000) |
| Leber's hereditary optic atrophy | Hereditary degeneration of the optic nerve and papillomacular bundle with resulting rapid loss of central vision, progressive for several weeks, then usually stationary with permanent central scotoma; age of onset is variable, most often in the third decade; more males than females are affected and transmission is cytoplasmic and strictly on the female side. Mutation on the mitochondrial chromosome involved, which presumably interacts with an X-linked mutant. This mechanism may explain the bizarre sex ratio, which differs significantly from one country to another. (05 Mar 2000) |