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At least 433 records · Page 24Linked to original sources
PubMed1988

Magnetic resonance imaging of the optic nerve in optic neuritis.

Magnetic resonance imaging (MRI) of the optic nerves using the STIR (short inversion time inversion recovery) sequence was performed in 37 adult patients with a recent or past attack of optic neuritis. MRI revealed high-signal regions in 84% of symptomatic and 20% of asymptomatic nerves. The mean longitudinal extent of lesions was 1 cm. Slow or poor visual recovery was associated with more extensive lesions, or lesions within the optic canal. Disk swelling was usually associated with anterior lesions but also occurred with lesions in the canal. Visual evoked potentials were even more sensitive than MRI in detecting lesions and are still the investigation of choice in suspected demyelinating disease involving the optic nerve.

Adult↗
PubMed2001

Vaccination for neuroprotection in the mouse optic nerve: implications for optic neuropathies.

T-cell autoimmunity to myelin basic protein was recently shown to be neuroprotective in injured rat optic nerves. In the present study, using the mouse optic nerve, we examined whether active immunization rather than passive transfer of T-cells can be beneficial in protecting retinal ganglion cells (RGCs) from post-traumatic death. Before severe crush injury of the optic nerve, SJL/J and C3H.SW mice were actively immunized with encephalitogenic or nonencephalitogenic peptides of proteolipid protein (PLP) or myelin oligodendrocyte glycoprotein (MOG), respectively. At different times after the injury, the numbers of surviving RGCs in both strains immunized with the nonencephalitogenic peptides pPLP 190-209 or pMOG 1-22 were significantly higher than in injured controls treated with the non-self-antigen ovalbumin or with a peptide derived from beta-amyloid, a non-myelin-associated protein. Immunization with the encephalitogenic myelin peptide pPLP 139-151 was beneficial only when the disease it induced, experimental autoimmune encephalomyelitis, was mild. The results of this study show that survival of RGCs after axonal injury can be enhanced by vaccination with an appropriate self-antigen. Furthermore, the use of nonencephalitogenic myelin peptides for immunization apparently allows neuroprotection without incurring the risk of an autoimmune disease. Application of these findings might lead to a promising new approach for treating optic neuropathies such as glaucoma.

Animals↗
PubMedDate not supplied

[Topography and angioarchitectonics of the orbital portion of the optic nerve according to ultrasonic findings and data of three-dimensional optic analysis].

Super-sharp gray scale image, highly sensitive digital wide-band Doppler analysis, three-dimensional visualization of vessels in pulsed energy Doppler mode, and three-dimensional optic tomography of the optic disk were used in examination of the posterior segment of the eye in 20 healthy volunteers (40 eyes) aged 20-50 years. Vascular network of the optic nerve was examined under clinical conditions; blood filling of elements of the Zinn-Haller arterial circle, reticular plate, and posterior short ciliary arteries were studied. Vascular architectonics of the retrobulbar space was studied by three-dimensional reconstruction in the energy Doppler mode and biometrical parameters of intraocular and retrobulbar part of the optic disk were determined.

Adult↗
PubMed2002

[Angiographic changes in optic disc and its surrounding choroid after contusion of optic nerve].

PURPOSE: To study the angiographic changes in the optic disc and its surrounding choroidoretina after optic nerve contusion with fundus fluorescein angiography (FFA), and indocyanine green angiography (ICGA). METHODS: Thirty patients (30 eyes) with various degree of optic nerve damage caused by ocular contusion were examined with FFA and ICGA. (The choroidal rupture were excluded in this study). RESULTS: All patients present some abnormal angiography except one case. The main findings in FFA were hypofluorescein on quadrantal or entire disc in the early phase and leakage or persistent nonperfusion in the late phase. Meanwhile, the choroid surrounding disc was clearly delayed in its choroidal filling time. The retinal pigment epithelium (RPE) damage was observed over the localized abnormally perfused choroid. However, the RPE above the circular area around the disc which was hypofluorescein in ICGA showed no RPE damage in 9 cases. There are 2 cases combined with branche retinal vein occlusion and 19 (63%) cases showed ischemic changes exactly on the location of so-called "water separating zone". The visual acuity was not more than 0.1 in 80% of the patients in this study. CONCLUSIONS: There is severe optic nerve lesion in the strong ocular contusion, in which the choroidal and retinal arterial circulation has also been seriously damaged. The FFA and ICGA should be conducted in time in order to judge the injury correctly and allow the clinician to better manage the cases.

Adolescent↗
PubMed2004

[Acute anterior ischemic optic neuropathy in association with optic nerve drusen].

The authors present a case of 31 years old male, with superficial optic disc drusen, complicated with acute anterior ischemic optic neuropathy. The diagnosis was specified clinically, by fluorescein angiography, and by ultrasonography. The disease, very rare cited in the literature, is characteristic for the young adult and has a good prognosis. The unknown pathogeny gives an important place to the compression of the nervous fibres/ciliary circulation by the optic disc drusen, in a limited space and with a high density of optic fibres.

Acute Disease↗
PubMed1990

[Idiopathic inflammation of the optic nerve simulating optic nerve sheath meningioma].

A case of idiopathic inflammation of the optic nerve (perioptic neuritis) which simulated optic nerve sheath meningioma is reported and the literature reviewed. In this case, idiopathic inflammation of the optic nerve caused enlargement of the nerve and its sheath, showing a tubular diffuse thickening with a central hypodense area (tram-tracking sign). thus mimickling the cancers morphology idiopathic perioptic neuritis is an important condition for, the differential diagnosis of visual loss when CT demonstrates enlargement of the optic nerve.

Cranial Nerve Neoplasms↗
PubMed1978

[Correlation between conduction velocities in fibers of the optic nerve and optic radiation in cats].

The responses of dorsal lateral geniculate body units to striate cortex and optic chiasm stimulation were examined in cats immobilized with d-tubocurarine. A high correlation between antidromic responses to striate cortex and orthodromic responses to optic chiasm stimulation was found (r=0.895; P=0.01). 9% of neurons responded antidromically to optic chiasm stimulation indicating the existence of centrifugal fibres in the optic nerve. The functional significance of time dispersion of the afferent volley in visual system is discussed.

Animals↗
PubMed1995

Regenerative and other responses to injury in the retinal stump of the optic nerve in adult albino rats: transection of the intracranial optic nerve.

The response to injury of the proximal (retinal) stump of the intracranially transected optic nerve in adult rats has been studied by electron microscopy. The central part of the retinal stump of the optic nerve underwent severe ischaemic damage resulting in the formation by 3 days postoperation (dpo) of a cone-shaped region of necrotic tissue which extended from a base occupying most of the cross-sectional area of the nerve at the cut end to an apex within the intraorbital part of the nerve and only 2-3 mm from the eyeball. A mixture of apparently viable and dead or dying cells and axons was present in an intermediate zone surrounding the ischaemic core. Apparently intact nerve fibres occupied most of the periphery of the optic nerve. Small bundles of sprout-like axons were seen in the intermediate zone at 3 dpo, and by 5 dpo such sprouts were present at the periphery of the degenerative core. By 7 dpo, the sprouts were also found in the centre of the degenerative core, accompanied by astrocyte processes. The number of axonal sprouts present in the degenerative core and intermediate zone was much higher at 2 and 4 wk postoperation (wpo) than at 7 dpo, then declined gradually by 6 and 8 wpo. These results show that intracranial transection of the rat optic nerve produces extensive degeneration in the proximal stump and effectively produces an intraorbital axotomy of many retinal ganglion cells. Nevertheless, surviving axons display the ability to produce regenerative sprouts which persist for considerably longer than those produced after intraorbital injury.

Animals↗
PubMed1994

[Optic neuropathy caused by alcoholism and smoking: a diagnostic pitfall of Leber's optic neuropathy].

A 39 year-old patient suffered bilateral painless visual loss while consuming abusively alcohol and cigarettes. Family history was remarkable for a similar episode in the patient's brother 21 years ago, while drinking and smoking heavily. A diagnosis of toxic optic neuropathy was made in another institution, but due to the positive family history, mitochondrial DNA was studied for a point mutations associated with Leber's hereditary optic neuropathy. A homoplasmic mutation at nucleotide 11778 was found. The patient's brother could not be studied. This case emphasizes the probable deleterious effects of epigenetic factors such as alcohol and cigarette smoke in patients harbouring mitochondrial DNA mutations associated with Leber's hereditary optic neuropathy and the need for mitochondrial DNA studies in atypical cases of optic neuropathy.

Adult↗
PubMed1993

[Fluorescein angiographic findings regarding the optic disc in cases of low-tension glaucoma and the chronic stage of anterior ischemic optic neuropathy].

The optic disc was studied by stereofluorescein angiography in 7 cases of the chronic stage of anterior ischemic optic neuropathy (AION) and 20 cases of low-tension glaucoma (LTG), to clarify the difference in vasculature. In the LTG patients, a selective and well-defined decrease of laminar and prelaminar capillaries in the upper and (or) lower temporal area of the optic disc was found in 38 (95%) of 40 eyes in the 20 cases. In the AION patients, a decrease of laminar and prelaminar capillaries was also found in 3 (43%) of 7 eyes in the 7 unilateral cases, but the specific area and form of vascular reduction were not found. These results show that the angiographic picture of the optic disc in LTG is clearly different from that in AION.

Adult↗
PubMedDate not supplied

Cupping of the optic disc in ischemic optic neuropathy.

Stereophotographs of the optic disc were reviewed in 78 patients with ischemic optic neuropathy (ION). Only 10% (6) of 61 nonarteritic (idiopathic) ION eyes developed optic disc cupping similar to that seen in glaucomatous eyes. Five of ten eyes with ION due to giant cell arteritis had cupping simulating glaucoma; however, two had elevated intraocular pressure, and the other three had large physiologic cups in the opposite eye. Optic disc pallor was proportionately more severe in ION eyes than in glaucomatous eyes of similar cup size. While there are similarities in the type of visual field loss in ION and glaucoma, the two disorders differ in the usual appearance of the disc after field loss has occurred and in the portion of the field most frequently affected. These observations suggest that if both disorders have an ischemic mechanism, there is a difference in the nature or distribution of the ischemia. There should be little difficulty under most circumstances in making the clinical differentiation between a disc that has suffered ION and a disc that has suffered pressure-induced damage, although occasional instances of ION may be classified as low-tension glaucoma on the basis of field loss and cupping without elevated intraocular pressure.

Acute Disease↗
PubMed1997

Guanylate cyclase activity in retina optic nerve and optic chiasm of rats under different illumination conditions.

In the present work we have measured the guanylate cyclase activity in soluble fractions from several tissues relevant to the visual response under different illumination conditions. Guanylate cyclase was sensitive to changes of light/dark periods in incubated extract obtained from soluble fractions of retina, optic nerve and optic chiasm. The changes in soluble guanylate cyclase activity found, about 100 fold between dark and light periods in those tissues, indicate a key role for this enzyme. The results showed that light inhibit strongly the soluble retinal guanylate cyclase activity; while it increases the activity of this enzyme in the optic nerve. A generalized photoinhibited response of soluble guanylate cyclase was observed in all studied tissues in prolonged dark adapted animals. The effect of Na+ 1 and 10 mM, and free Ca++ 28 eta M and 2.8 microM on the guanylate cyclase activity was performed in the studied tissues. The enzymatic activity appeared to be inversely related in the retina and optic nerve with regard to the ion exposure, which may involve different ionic control mechanisms. All indicate an active role for the soluble guanylate cyclase in the phototransduction process not only in retina, also in other tissues relevant in the visual response.

Adaptation, Ocular↗
PubMed1980

Cavitary developmental defects of the optic disc. Visual loss associated with optic pits and colobomas.

Congenital cavitary anomalies of the optic disc (optic pit and coloboma) are uncommon and frequently go unrecognized. Patients with these defects have a high incidence of visual loss and the abnormal appearance of the discs may be mistaken for atrophy due to acquired neurological disease. Occasionally, associated midline neurological developmental malformations will be found associated with pits, colobomas, or other dysplastic optic discs, as in one of our cases. A group of patients with optic pits and colobomas referred for neurological evaluation of visual loss are presented to remind the neurologist of the appearance of these congenital crater-like defects and of the causes of loss of vision.

Adult↗
PubMed1991

Optic nerve sheath decompression for nonarteritic ischemic optic neuropathy improves multiple visual function measurements.

Optic nerve sheath decompression was performed in seven patients with nonarteritic anterior ischemic optic neuropathy. Visual function was evaluated by measurement of visual acuity with standardized Early Treatment Diabetic Retinopathy Study charts, color vision testing, quantitation of relative afferent pupillary defects with neutral-density filters, and Goldmann and Humphrey perimetry. Visual acuity improved markedly in all patients (at least doubling of the visual angle); the peripheral visual field expanded by at least 20 degrees (as measured by Goldmann perimetry) in six patients. Three patients also experienced marked improvement in color vision, relative afferent pupillary defect, and foveal sensitivity. Our experience supports the possible beneficial effect of optic nerve sheath decompression in patients with nonarteritic anterior ischemic optic neuropathy.

Aged↗
PubMed1993

Optic nerve sheath fenestration for treatment of progressive ischemic optic neuropathy. Results in 26 patients.

Optic nerve sheath fenestration was performed in 26 eyes for treatment of the progressive type of common (nonarteritic) anterior ischemic optic neuropathy. During a mean follow-up period of 21 weeks (range, 6 to 52 weeks), results were as follows: visual acuity increased by two or more lines on the Snellen chart in 7 eyes; visual acuity decreased by two or more lines in four eyes; some regression of visual field defects occurred in six eyes, including two eyes in which acuity also improved. These results, attributed to surgical decompression, do not exceed the spontaneous recovery rates reported in the literature pertaining to nonarteritic anterior ischemic optic neuropathy and fail to substantiate the sanguine visual outcome in recently reported series of patients undergoing optic nerve sheath decompression.

Aged↗
PubMed2003

Electrochemical optical waveguide lightmode spectroscopy (EC-OWLS): a pilot study using evanescent-field optical sensing under voltage control to monitor polycationic polymer adsorption onto indium tin oxide (ITO)-coated waveguide chips.

A new technique has been developed that combines evanescent-field optical sensing with electrochemical control of surface adsorption processes. This new technique, termed "electrochemical optical waveguide lightmode spectroscopy" (EC-OWLS), proved efficient in monitoring molecular surface adsorption and layer thickness changes of an adsorbed polymer layer examined in situ as a function of potential applied to a waveguide in a pilot study. For optical sensing, a layer of indium tin oxide (ITO) served as both a high-refractive-index waveguide and a conductive electrode. In addition, an electrochemical flow-through fluid cell was provided, which incorporated working, reference, and counter electrodes, and was compatible with the constraints of optical sensing. Poly(L-lysine)-grafted-poly(ethylene glycol) (PLL-g-PEG) served as a model, polycation adsorbate. Adsorption of PLL-g-PEG from aqueous buffer solution increased from 125 to 475 ng/cm(2 )along a sigmoidal path as a function of increasing potential between 0 and 1.5 V versus the Ag reference electrode. Upon buffer rinse, adsorption was partially reversible when a potential of >/=0.93 V was maintained on the ITO waveguide. However, reducing the applied potential back to 0 V before rinsing resulted in irreversible polymer adsorption. PLL-g-PEG modified with biotin demonstrated similar adsorption characteristics, but subsequent streptavidin binding was independent of biotin concentration. Applying positive potentials resulted in increased adsorbed mass, presumably due to polymer chain extension and reorganization in the molecular adlayer.

Adsorption↗
PubMed1991

Experimental and theoretical investigations on the validity of the geometrical optics model for calculating the stability of optical traps.

We have developed a computer program based on the geometrical optics approach proposed by Roosen to calculate the forces on dielectric spheres in focused laser beams. We have explicitly taken into account the polarization of the laser light and thd divergence of the laser beam. The model can be used to evaluate the stability of optical traps in a variety of different optical configurations. Our calculations explain the experimental observation by Ashkin that a stable single-beam optical trap, without the help of the gravitation force, can be obtained with a strongly divergent laser beam. Our calculations also predict a different trap stability in the directions orthogonal and parallel to the polarization direction of the incident light. Different experimental methods were used to test the predictions of the model for the gravity trap. A new method for measuring the radiation force along the beam axis in both the stable and instable regions is presented. Measurements of the radiation force on polystyrene spheres with diameters of 7.5 and 32 microns in a TEM00-mode laser beam showed a good qualitative correlation with the predictions and a slight quantitative difference. The validity of the geometrical approximations involved in the model will be discussed for spheres of different sizes and refractive indices.

Lasers↗