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At least 91 records · Page 5Linked to original sources
PubMed1988

[Neutron spin tomography of the optic nerve in retrobulbar neuritis and optic nerve atrophy: demonstration of inflammation and demyelination].

Detection of inflammatory lesions of the optic nerve by magnetic resonance imaging requires a special imaging technique. In 3 patients with persisting visual loss due to retrobulbar neuritis we scanned the optic nerve with a short inversion recovery sequence. In each of the 3 patients magnetic resonance imaging revealed inflammatory lesions in the intracanalicular portion of the optic nerve. It is supposed that the unfavorable location of the lesions in the optic canal is responsible for the poor recovery of visual acuity. In another patient with a bilateral optic nerve atrophy demyelination of the optic nerve could be made visible.

Adult↗
PubMed1989

Peripheral nerve regeneration through optic nerve grafts.

Grafts of optic nerve were placed end-to-end with the proximal stumps of severed common peroneal nerves in inbred mice. It was found that fraying the proximal end of adult optic nerve grafts to disrupt the glia limitans increased their chances of being penetrated by regenerating peripheral nerve fibres. Suturing grafts to the proximal stump also enhanced their penetration by axons. The maximum distance to which the axons grew through the CNS tissue remained about 1.5 mm from 2-12 weeks after grafting. Schwann cells were seldom identified in the grafts. Varicose and degenerating nerve fibres were often seen within the grafts. Some varicose profiles were shown to be the terminal parts of axons within the grafts. Axons containing clusters of organelles resembling synaptic vesicles became more abundant in the longer-term grafts. Immunohistochemical studies performed on sutured grafts using a polyclonal antiserum to neurofilaments confirmed the impressions given by the electron microscopical observations. Grafts of neonatal optic nerve lacked myelin debris but were not usually penetrated by regenerating peripheral axons within a 6-week period. Sixty minutes after the intravenous injection of horseradish peroxidase, reaction product could be detected in the extracellular spaces around blood vessels in all types of living optic nerve graft. This indicates that blood-borne macromolecules could penetrate the grafts. However, the profiles of axons which were found within living optic nerve grafts had no obvious relationship to blood vessels and were usually surrounded by astrocytic processes. These results suggest that living astrocytes, rather than the absence of serum-derived trophic factors or the presence of CNS myelin, constitute the major barrier to the extension of axons and the migration of Schwann cells into CNS tissue.

Age Factors↗
PubMed1997

Diameter of the optic nerve in idiopathic optic neuritis and in anterior ischemic optic neuropathy.

PURPOSE: There is considerable overlap in the clinical profile of patients with idiopathic optic neuritis (ON) and anterior ischemic optic neuropathy (AION). We tested the hypothesis that the retrobulbar diameter of the optic nerve may be a criterion for the differential diagnosis between ON and AION. METHODS: The diameter of the optic nerve was measured by B-scan ultrasonography with the eye in an abducted position. Only patients with a unilateral optic neuropathy were included, 16 ON patients (mean age 24 years, 5 with and 11 without disc swelling) and 9 patients with AION (mean age 72 years). As controls for the ON patients 10 young normal subjects (mean age 25 years) and as controls for the AION patients 10 elderly subjects with eye problems not related to the optic nerve (mean age 76 years) were examined. RESULTS: In the ON patients with disc swelling the diameter of the optic nerve was 5.4 +/- 0.5 mm in the affected and 3.0 +/- 0.3 mm in the unaffected side. This difference was significant (Wilcoxon-test, p = 0.043). In the ON patients without disc swelling the diameter of the optic nerve was 4.4 +/- 0.4 mm in the affected and 3.0 +/- 0.3 mm in the unaffected side. This difference was significant (Wilcoxon-test, p = 0.003). In the AION patients the diameter of the optic nerve was 3.0 +/- 0.3 mm on the affected and 2.8 +/- 0.4 mm on the unaffected side. This difference was not significant (Wilcoxon-test, p = 0.093). Comparing the optic nerves with ON and AION to those of the controls, the diameter was significantly enlarged in the nerves with ON and normal in the nerves with AION (one factor repeated ANOVA). CONCLUSION: The diameter of the optic nerve is increased in ON without disc swelling and even more so in ON with disc swelling. The enlargement is probably due to edema of the nerve itself, not the surrounding subarachnoidal space. In AION, the diameter of the optic nerve is normal. Measuring the diameter of the optic nerve by B-scan ultrasonography is particularly useful in the differential diagnosis between ON with disc swelling and AION.

Adolescent↗
PubMed1992

Optic nerve decompression for indirect posterior optic nerve trauma.

Posterior indirect optic nerve trauma is a rare but possibly dramatic event. Since spontaneous recovery is unlikely, medical treatment by megadose steroid therapy is advocated. Optic nerve decompression may be usefull, but is still controversial. Medial optic canal wall decompression seems best and may be achieved by various approaches.

Adult↗
PubMed1989

Optic nerve head measurements: the optic nerve head analyzer--its advantages and its limitations.

The Optic Nerve Head Analyzer (ONHA) calculates by means of computer-assisted analysis of stereo images different parameters of the optic disc: disc diameter, disc size, cup/disc ratio (CDR), neuroretinal rim area, and excavation volume for the disc quadrants and for the total disc. To obtain first indications of the clinical value of ONHA measurements for diagnosis and follow-up in glaucoma we examined the reproducibility of measurement results for different diseases. Furthermore, we studied the mean values of the different disc parameters in healthy eyes. It was investigated: 1) whether the reproducibility is different in the different disc parameters; 2) whether the reproducibility in different eye diseases is different as compared to healthy eyes; 3) by which criteria the reproducibility is influenced; 4) whether there is a correlation between disc size and size of rim area. The reproducibility was studied in 178 eyes of 178 patients, who were all examined twice with the ONHA. The mean difference between the results of first and second measurement was calculated for the different disc parameters. Differences were found in the reproducibility of the parameters: e.g., the mean difference between first and second measurement was 1.8 percent for the disc size, and 5.6 percent for the neuroretinal rim area. For the disc quadrants, the reproducibility of values was worse than for the total disc. No marked differences of reproducibility of disc parameters were found for different diseases. Reproducibility depends, for instance, upon correct determination of the disc margin. In healthy eyes, a significant correlation was found between rim area and disc size: larger discs have a larger neuroretinal rim area than smaller discs. Thus, the rim areas of different eyes are only comparable for equally sized discs. Relative values, as for instance, cup/disc ratio, or the quotient of rim area and disc size, are therefore better suited for comparison of different eyes than absolute values. The recent developments in automatic disc analysis equipment and the clinical relevance of the results for diagnosis and follow-up in glaucoma are discussed.

Diagnosis, Computer-Assisted↗
PubMedDate not supplied

[Follow up results and pathogenetic substantiation of the effect of decompression surgery on the optic nerve in glaucomatous optic neuropathy].

Retrospective analysis of the efficiency of optic nerve decompression in progressive glaucomatous optic neuropathy in patients with normalized intraocular pressure showed widening and/or stabilization of the visual field in remote periods (6-11 years) in 83.3% patients. Study of the hemodynamics after optic nerve decompression showed a significant improvement of the hemodynamic parameters in the orbital artery-central retinal artery system: increased bloodflow velocity in the central retinal artery, increase of ophthalmic blood pressure and perfusion pressure, dilatation of the arteries, and constriction of veins, which indicates improvement of hemoperfusion in the initial portion of the optic nerve and retina after decompression surgery on the optic nerve. Extension and stabilization of visual field correlated with positive changes in circulation.

Decompression, Surgical↗
PubMed1982

Indirect imaging of the canine optic nerve, using metrizamide (optic thecography).

Between the optic nerve and its sheath is a small, CSF-filled space that communicates with the subarachnoid space of the brain. A technique for the radiographic opacification of the optic nerve subarachnoid space following the intrathecal injection of metrizamide was investigated in 8 dogs. The technique enabled indirect visualization of the optic nerves from the optic chiasm to the eyeball and of structures within the subarachnoid basal cisterns of the brain, including the optic chiasm, hypophysis, and blood vessels of the cerebral arterial circle. Displacement and obstruction of the optic nerve subarachnoid space were demonstrated after surgically creating optic nerve lesions to simulate orbital tumors and trauma. The technique was found to be safe, effective, and advantageous over other techniques currently available for the visualization of these structures.

Animals↗
PubMed1986

Decompression of the optic nerve in the optic canal. A transorbital approach.

Blindness can result from pressure on the optic nerve in the optic canal, either from trauma or from neoplasm. The usefulness, timing, and technique of surgical decompression of the optic canal remains controversial. The present paper describes eight patients with optic nerve compression, who had the optic nerve decompressed through a transorbital approach. Because this technique is technically simple and is associated with a low morbidity, it offers a treatment alternative to this difficult group of patients.

Adolescent↗
PubMed1991

Prostaglandin E2 changes in the retina and optic nerve of an eye with injured optic nerve.

Changes in arachidonic acid metabolism were studied in the optic nerve, the chorioretina, and in the vitreous following crush injury to the optic nerve of rats. Crush injury led to: (i) a 3.9-fold increase in optic nerve prostaglandin type E2 in vitro production which peaked on day 5 and was followed by a gradual decline, but was still significantly higher than baseline levels by day 12; (ii) a two-fold increase in the chorioretina prostaglandin type E2 in vitro production which peaked on day 1, and resumed baseline levels by day 3; (iii) a 3.5-fold increase in vitreous prostaglandin type E2 levels on day 1 which remained at 1.5-2 times higher than baseline levels for the rest of the study period (12 days). The findings indicate that the pattern of changes in prostaglandin type E2 production by the optic nerve (consisting mostly of white matter) is different from that described for injured brain tissues. The prolonged accumulation of vitreal prostaglandin type E2 in eyes with damaged optic nerve may lead to undesirable effects on the retina beyond those directly manifested in the retina by altered axonal flow in the injured optic nerve.

Animals↗
PubMed1997

MRI of optic nerve enlargement in optic neuritis.

We report two cases of optic neuritis with optic nerve enlargement on MRI. Both had a clinical course typical for optic neuritis but also had a neuroradiologic finding most commonly seen with optic nerve glioma or meningioma, which initially led to an incorrect diagnosis. We review the six previous reported cases of optic nerve enlargement in optic neuritis. Including our cases, six of eight reported cases were in children with severe initial visual loss. Optic nerve enlargement is a rare finding in optic neuritis that might be a subtype of optic neuritis.

Child↗
PubMed1996

[Optic nerve sheath enlargement and reversal of optic nerve head in pseudotumor cerebri].

Using standard cerebral computerized tomography (CT), we diagnosed pseudotumor cerebri (PTC) and correlated the CT findings with CSF pressure and severity of visual impairment. 13 patients with a clinical diagnosis of PTC were compared with 20 age-matched controls with headache, but without papilledema or other neurologic signs. Cerebral CT consisted of axial sections of the posterior fossa, including the orbits. In all subjects the diameter of the optic nerve sheath, reversal of the optic nerve head, presence of empty sella, and size of the ventricles, cisterns and sulci were evaluated. There were no differences in basal cisterns and ventricles between those with PTC and control subjects. Empty sella was found in 6 of 13 PTC patients, compared with 1 of the 20 controls. Optic nerve sheath diameter in controls ranged from 3.5-5.0 mm (average 4.2 +/- 0.54 mm) but from 4.5-9.0 mm (average 6.8 +/- 1.54 mm) in those with PTC. Reversal of the optic nerve head was seen in 4 cases of PTC but in none of the controls. In PTC patients with opening CSF pressure greater than 270 mm water, the diameter of the optic nerve was wider than 7.5 mm. Thus, in most cases of PTC, bilateral enlarged optic nerves can be measured by standard cerebral CT and intracranial space-occupying lesions can be excluded as well. Moreover, reversal of optic nerve head, and empty sella can frequently be seen on CT in those with PTC.

Adolescent↗
PubMed1995

Optic nerve fiber count and diameter of the retrobulbar optic nerve in normal and glaucomatous eyes.

BACKGROUND: The caliber of the retrobulbar optic nerve and the count of optic nerve fibers vary considerably in normals. The diameter of the retrobulbar optic nerve also decreases with optic nerve atrophy. This study aimed to determine the relationship between the caliber of the optic nerve and the optic nerve fiber count. METHODS: We counted the optic nerve fibers and measured the diameter of histological cross sections of the optic nerve for 56 normal subjects and 23 patients with absolute glaucoma. RESULTS: The optic nerve fiber count increased significantly (P < 0.0001) by 777,000 fibers for every millimeter increase in retrobulbar optic nerve diameter, starting at a baseline diameter of 1.89 mm. CONCLUSION: Using this linear regression equation, the optic nerve fiber count can be estimated in routine histology by measuring the optic nerve diameter. Taking into account a fixation-induced tissue shrinkage, this method may also give some indication of the optic nerve fiber count intravitally, when, for eyes with opaque optic media, the diameter of the retrobulbar optic nerve has been measured by imaging techniques. Greater retrobulbar optic nerve caliber may indicate greater structural reserve capacity.

Adult↗
PubMed1960

Electron microscope and x-ray diffraction studies of the effects of dehydration on the structure of nerve myelin. II. Optic nerve.

The dehydration of rat optic nerve has been studied by allowing specimens to become partially or fully dried before fixation and preparation for electron microscopy. A correlation is established between electron micrographs of the myelin sheath and corresponding small-angle x-ray diffraction patterns. The modifications of the optic nerve myelin layers during drying were very similar to those described in more detail for the myelin of frog sciatic nerve. The most striking difference was that the system of fine layers characteristic of the fully dried myelin was much more extensive in the case of the optic nerve, and the layer thickness was significantly greater than the corresponding layer in the frog sciatic nerve preparation. The significance of these correlations is discussed.

Animals↗