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Nerve Fibre Layer (nerve + fibre_layer)

Distribution by Scientific Domains
Medical Sciences88%

Kinds of Nerve Fibre Layer

  • retinal nerve fibre layer
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    Selected Abstracts

    Defining Cytochemical Markers for Different Cell Types in the Equine Retina

    ANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 6 2006
    C. A. Deeg
    Summary The major cell types in the mammalian retina are photoreceptors, amacrine, horizontal, bipolar, ganglion and Mueller glial cells. Most of the specific cell types are conserved, but cytochemical markers vary between species. The aim of our study was to characterize cytochemically distinctive markers for different cell types in the equine retina. We were able to define specific markers for equine Mueller glial cells and photoreceptor cells. Furthermore, we describe markers for large ganglion cells, horizontal and amacrine cells and a subpopulation of bipolar cells. Additionally, discrimination between the inner plexiform layer and nerve fibre layer can be achieved by expression of syntaxin and neurofilament 200 respectively. [source]

    Axonal loss occurs early in dominant optic atrophy

    ACTA OPHTHALMOLOGICA, Issue 3 2010
    Dan Milea
    Abstract. Purpose:, This study set out to investigate retinal nerve fibre layer (RNFL) thickness and best corrected visual acuity (BCVA) in relation to age in healthy subjects and patients with OPA1 autosomal dominant optic atrophy (DOA). Methods:, We carried out a cross-sectional investigation of RNFL thickness and ganglion cell layer density in 30 healthy subjects and 10 patients with OPA1 DOA using optical coherence tomography (OCT). We then performed a regression analysis of RNFL thickness and BCVA versus age. Results:, Both healthy subjects and DOA patients demonstrated a gradual reduction in RNFL thickness with age; the relationship was best described statistically by a model that assumed a constant offset between the two groups. Best corrected VA decreased significantly with age in DOA patients, in whom BCVA was correlated with peripapillary RNFL thickness in the inferior and superior peripapillary quadrants and with total macular thickness at eccentricities of 500,3000 ,m. The observations were best described by a constant offset of 41.9 ,m separating the two groups and an annual decrease in RNFL thickness of 0.48 ,m (p < 0.0001). In patients with DOA, increasing age was associated with decreasing BCVA (p = 0.046). Conclusions:, This cross-sectional study found evidence of comparable age-related decreases in RNFL thickness in healthy subjects and in DOA patients, where the deficit in DOA patients is best described using a model that assumes the deficit between the groups does not vary with age. The gradual reduction of BCVA with age may be a consequence of a relative deficit in RNFL thickness that is established before the second decade of life. [source]

    Scanning laser polarimetry with variable corneal compensation in migraine patients

    ACTA OPHTHALMOLOGICA, Issue 7 2009
    Antonio Martinez
    Abstract. Purpose:, This study aimed to compare scanning laser polarimetry measurements of retinal nerve fibre layer (RNFL) thickness in eyes of migraine patients with those in eyes of age-matched, healthy subjects. Methods:, The study was designed as an observational, prospective, cross-sectional study. It included 57 eyes of 57 patients with migraine with or without aura according to the criteria of the International Headache Society and 44 eyes of 44 age-matched healthy controls. Scanning laser polarimetry images were obtained using a commercial GDx VCC system (Version 5.3.1; Laser Diagnostic Technologies, Inc.). At each sitting, three sets of GDx VCC measurements were acquired for each patient and used in the analysis. Image acquisition was performed in undilated eyes in all subjects. Results:, The mean ± standard deviation RNFL average thickness parameter in the migraine subjects was significantly lower than in the control group, at 50.4 ± 4.8 ,m versus 54.7 ± 3.4 ,m, respectively (p < 0.0001). However, there were no differences between migraine subjects and controls in mean RNFL thickness in superior and inferior areas. In the migraine group the mean migraine disability assessment (MIDAS) score was 34.3 ± 15.3 and the mean number of attacks per year was 17.1 ± 6.9 (range 6,28). The mean RNFL average thickness parameter was significantly correlated with MIDAS score (r = , 0.86, p < 0.0001) and frequency of attacks (r = , 0.86, p < 0.0001). Conclusions:, The mean RNFL average thickness parameter was found to be thinner in migraine patients. In addition, we found a strong correlation between migraine severity and RNFL average thickness parameters. [source]

    The role of optical coherence tomography in the detection of pituitary adenoma

    ACTA OPHTHALMOLOGICA, Issue 7 2009
    Charlotta Johansson
    Abstract. Purpose:, To analyse retinal nerve fibre layer (RNFL) thickness in eyes with compression of the optic chiasm by a pituitary adenoma. RNFL thickness was analysed with optical coherence tomography (OCT) and compared to visual field measurements using high-pass resolution perimetry (HRP). Methods:, Sixteen eyes from eight patients with pituitary adenoma were studied. All had bitemporal visual field depression caused by compression of the optic chiasm. Patients were submitted to an ophthalmic examination more than 14 months after surgery (seven patients had undergone trans-sphenoidal and one trans-cranial adenomectomy). The examination included HRP, fundus photography and measurement of the peripapillar RNFL thickness using OCT. Results:, In spite of temporal visual field depression, not all eyes showed reduced RNFL thickness by OCT. This was also true for some eyes in which RNFL was judged to be reduced on fundus photographs. Contrary to our expectations, RNFL thickness in the nasal quadrant was normal in nine of the 16 eyes. Corresponding figures for the superior, inferior and temporal quadrants were eight, six and five, respectively. The overall RNFL thickness, as measured by OCT, did not correlate well with neural capacity, which is an index of remaining retino-cortical neural channels in HRP. Conclusion:, RNFL thickness as measured with OCT was reduced in most, but not all, eyes with temporal field depression caused by chiasmal compression. The pattern of RNFL loss did not correlate well with the visual field defect. Sensitivity of RNFL thickness measurement in OCT was low. The method has limited value in the diagnosis of pituitary tumour compression. [source]

    Endothelial dysfunction in glaucoma

    ACTA OPHTHALMOLOGICA, Issue 1 2009
    Hemma Resch
    Abstract. Glaucoma is a group of ocular diseases characterized by optic neuropathy associated with loss of the retinal nerve fibre layer and re-modelling of the optic nerve head, and a subsequent particular pattern of visual field loss. Increased intraocular pressure is the most important risk factor for the disease, but the pathogenesis of glaucoma is not monofactorial. Among other factors, ischaemia and vascular dysregulation have been implicated in the mechanisms underlying glaucoma. The vascular endothelium plays an important role in the regulation of ocular blood flow and pathological alterations of vascular endothelial cells may induce ischaemia and dysregulation. The present review summarizes our current evidence of endothelial dysfunction in glaucoma. This is of interest because endothelial dysfunction is a good prognostic factor for progression in several diseases. Although such data are lacking for glaucoma, endothelial dysfunction may provide an attractive target for therapeutic intervention in open-angle glaucoma and other vascular disorders of the eye. [source]

    Characterization of vigabatrin-associated optic atrophy

    ACTA OPHTHALMOLOGICA, Issue 5 2003
    Lars Frisén
    Abstract. Aims:,To report the discovery of a previously unknown form of optic atrophy associated with use of the anti-epileptic drug vigabatrin. Methods:,We conducted a retrospective analysis of digitally enhanced ocular fundus photographs, kinetic visual field maps and treatment parameters for 25 patients, who were selected to represent a large spectrum of visual field defects. Results:,In all, 21 patients (84%) evidenced subtle, diffuse atrophy of the retinal nerve fibre layer, in a pattern accessible to scoring. Atrophy scores correlated with visual field remains and cumulative vigabatrin doses. A pathophysiological model is proposed that involves the lengths of intraocular (unmyelinated) retinal ganglion cell axons. Conclusion:,Optic atrophy attests to the irreversible nature of vigabatrin's visual toxicity. Ocular fundus imaging should prove useful for objectively monitoring vigabatrin-treated subjects for visual toxicity. [source]

    Short wavelength automated perimetry

    ACTA OPHTHALMOLOGICA, Issue 6 2001
    John M. Wild
    ABSTRACT. Short Wavelength Automated Perimetry (SWAP) utilizes a blue stimulus to preferentially stimulate the blue cones and a high luminance yellow background to adapt the green and red cones and to saturate, simultaneously, the activity of the rods. This review describes the theoretical aspects of SWAP, highlights current limitations associated with the technique and discusses potential clinical applications. Compared to white-on-white (W-W) perimetry, SWAP is limited clinically by: greater variability associated with the estimation of threshold, ocular media absorption, increased examination duration and an additional learning effect. Comparative studies of SWAP and W-W perimetry have generally been undertaken on small cohorts of patients. The conclusions are frequently unconvincing due to limitations for SWAP in the delineation of abnormality and of progressive field loss. SWAP is almost certainly able to identify glaucomatous visual field loss in advance of that by W-W perimetry although the incidence of progressive field loss is similar between the two techniques. Increasing evidence suggests that functional abnormality with SWAP is preceded by structural abnormality of the optic nerve head and/or the retinal nerve fibre layer. SWAP appears to be beneficial in the detection of diabetic macular oedema and possibly in some neuro-ophthalmic disorders. [source]

    Retinal nerve fibre layer of perimetrically unaffected eyes of glaucoma patients: an optical coherence tomography study

    CLINICAL & EXPERIMENTAL OPHTHALMOLOGY, Issue 2 2009
    Stefano Da Pozzo MD PhD
    Abstract Purpose:, The aim of this study is to evaluate whether optical coherence tomography (StratusOCT) may detect early changes in perimetrically unaffected (PU) fellow eyes of glaucomatous patients by assessing retinal nerve fibre layer (RNFL) thickness parameters. Methods:, Thirty-seven glaucomatous patients with unilateral field loss and 34 age-matched controls were recruited. In glaucoma patients, PU and perimetrically affected fellow eyes were analysed separately. For each group, mean values (±SD) of RNFL thickness parameters were calculated and comparisons between fellow eyes of glaucoma patients and between healthy and PU eyes of glaucoma patients conducted with paired t -test and Mann,Whitney U -test, respectively. Proportion of clock-hour sectors flagged with probability <5% or <1% was collected and differences between healthy and PU eyes were evaluated on Fisher exact test. Results:, Global (Average Thickness) and sectoral parameters (Inferior and Nasal Average), Maximum thickness,minimum thickness (Max-min), as well as 2-o'clock (nasal side) and 6-o'clock sectors resulted significantly thinner in PU eyes than in control group. Proportion of eyes with clock-hour position flagged with probability <5% or <1% was not significantly different between healthy and PU eyes. Conclusion:, Despite a standard automated perimetry within normal limits, the StratusOCT detected both localized and diffuse RNFL thinning in PU eyes of glaucoma patients. These eyes should be considered at risk of developing functional damage over time and consequently require thorough monitoring for detecting any sign of progression. [source]