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Optic Nerve Function (optic + nerve_function)
Selected Abstracts4341: Are visual evoked potentials and pattern ERG useful in neuro-ophthalmology?ACTA OPHTHALMOLOGICA, Issue 2010GE HOLDER Purpose To describe the roles of VEP and PERG in clinical neuroophthalmology. Methods Case based examples. Results Objective visual system testing with electrophysiology allows the distinction between optic nerve and macular dysfunction, often difficult in clinical practice. Examples will be shown of the types of VEP abnormality that can occur in different disorders of optic nerve function. PERG should also be performed in the patient with visual symptoms; if the PERG suggests macular dysfunction, full-field ERG is indicated in order to determine whether that macular dysfunction is part of a generalised retinal process or is dysfunction localised to the macula. Electrophysiology further allows the diagnosis of non-organic visual loss and the quantification of visual system dysfunction. Conclusion The objective functional assessment with electrophysiology is an important part of the diagnostic armamentarium available to neuroophthalmologists. [source] 2134: Arachnoid cell changes following elevated pressure and oxidative stress: new implications for optic nerve degenerationACTA OPHTHALMOLOGICA, Issue 2010A NEUTZNER Purpose The study of meningothelial cells (MCs) and their connection to optic nerve function. MCs line the arachnoid layer of the meninges and form a barrier between the CSF and the blood circulation. A previous study revealed a significantly increased proliferation of MCs in the arachnoid surrounding the optic nerve glaucoma patients. Methods To explore a possible role of these cells in the pathogenesis of diseases of the optic nerve, we studied the effect of elevated hydrostatic pressure and oxidative stress on MCs using rotenone to inhibit mitochondrial function and compared them to untreated control cells. Cell viability and proliferation were measured using a MTS-based assay. As a measure of barrier function, we assessed the endocytotic activity of MCs by fluorescence and confocal microscopy following fluorescent-latex bead uptake. Results Exposure of MCs to elevated hydrostatic pressure caused significant cellular proliferation and a dramatic decrease in endocytotic activity. Furthermore, mild oxidative stress severely inhibited endocytosis, thus negatively impacting MC barrier function. Conclusion MCs surround the optic nerve, thereby shielding it from but also conditioning the microenvironment of this sensitive area. As elevated pressure and oxidative stress occur in patients with increased intracranial pressure who have papilledema and probably in some cases of normal-tension glaucoma, these phenomena may impact the function of MCs and thus, contribute to the loss of retinal ganglion cells in the course of these and, perhaps, other optic nerve diseases. [source] Intravitreal treatment with Erythropoietin (EPO) preserves visual function following ocular ischemia in ratsACTA OPHTHALMOLOGICA, Issue 2007R DERSCH Purpose: Erythropoetin (EPO) is a promising neuroprotective drug. It is known that EPO reduces apoptosis of retinal ganglion cells following axotomy or glaucoma in rats. Until now, functional aspects of this neuroprotective effect have not been addressed. We investigated effects of EPO on retinal and optic nerve function and on the survival of retinal ganglion cells following ocular ischemia. Methods: Ocular ischemia was induced by increase of the IOP to 120mmHg for 55 min in Brown-Norway rats. Animals were treated intravitreally with 4U/eye (n=12) during the time of ischemia, controls (n=16) recieved BSS instead. Visual pathway was investigated by VEP 4 days after ischemia. Potentials were evoked by frequency and luminance modulated flicker stimuli and recorded in awake freely-moving rats. Retinal function was evaluated by ERG 7 days after ischemia. Retinal ganglion cells were labelled retrogradelly 4 days after ischemia and were quantified 6 days later in retinal flatmounts. Results: Both frequency and luminance modulated evoked potentials increased due to the application of EPO from 6±2% (mean in percent of the non-ischemic eye ± standard error) in control to 46±8% in treated animals and from 26±5% to 69±6% respectively. EPO increased responses of ischemic eyes from 31±6,V to 96±8,V (a-wave) and from 34±6,V to 110±15,V (b-wave). Morphologically, the intravitreal administration of EPO increased the number of surviving ganglion cells from 32±4% to 92±11%. Conclusions: We found a sizable functional benefit of intravitreal injection of EPO following interruption of ocular blood supply. This suggests that administration of EPO is a viable therapeutic option in ischemic retinal diseases. [source] Use of pupil size and reaction to detect orbital trauma during and after surgeryCLINICAL OTOLARYNGOLOGY, Issue 3 2004Farhan H. Zaidi We describe how pupillary reactions, used as an index of optic nerve function, can be elicited using only one working pupil. This is to challenge the conclusion of a study that did not appreciate this physiological phenomenon and thus gave rise to erroneous conclusions that might otherwise limit the scope of pupil measurements during and after surgery. For suitable cases, non-opioid anaesthesia and further clinical development of pupillometry are suggested by us as measures to monitor optic nerve function. [source] | ||||||||||