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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Documenta ophthalmologica 88 (1994), S. 27-37 
    ISSN: 1573-2622
    Schlagwort(e): Electroretinogram ; Electrophysiology ; Retinitis pigmentosa
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The achievement of a sharp retinal signal depends on many factors, particularly the stability of the electrodes on the corneal surface, the maximal reduction of electrical and electromagnetic disturbances and the avoidance of the noise caused by events that are synchronous with the stimulation. The availability of a low-noise recording system becomes critical in the detection of the electroretinogram in patients with retinitis pigmentosa. We studied an electroretinographic recording technique specifically designed to enhance the signal-to-noise ratio in patients with retinitis pigmentosa. The main features of the method are a membrane suction pump connected to the corneal electrodes to improve contact lens stability on the corneal surface, and a differential derivation system to record the signal. One corneal electrode is used as the recording electrode, while the other, acting as the reference electrode, is covered during full-field ganzfeld stimulation. In addition, computerized averaging and signal postrecording analyses were performed on 100 iterations. The methods described here resulted in a sharp reduction in the number of undetectable electroretinograms in our case material (28.8%). This investigation demonstrates that some of the undetectable signals reported in the literature may be due to noisy recording methods rather than to actually extinguished retinal responses.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 2
    ISSN: 1573-2622
    Schlagwort(e): Electroretinogram ; Kinetic perimetry ; Psychophysics ; Retinitis pigmentosa ; Visual field
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract To evaluate the relationship between Goldmann perimetry and maximal electroretinographic responses in patients with retinitis pigmentosa, analyses were performed on 220 affected subjects and separately on two subgroups with autosomal dominant (n = 35) and autosomal recessive (n = 29) inheritance. Electroretinograms were recorded averaging 100 iterations elicited with a 20-lux/s, 0.5-Hz white flash ganzfeld stimulation. The peripheral isopters of the visual fields were delimited with I4e, IIIe and V4e targets, measured on conventional perimetry charts with a light pen and expressed in square centimeters. Unlike most previously published reports, this investigation showed a definite correlation (p = 0.0001) between maximal electroretinographic response amplitude and visual field areas. This correlation was more evident for I4e and IIIe isopters (r = 0.89 and 0.87, respectively) than for V4e isopter (r = 0.69). This phenomenon appears to be related to distortion occurring on standard isometric charts and to spatial summation effects in the peripheral field. Such correlations held for both the autosomal dominant and autosomal recessive subgroups. It appears that, if enough accuracy is provided, maximal electroretinographic responses and Goldmann visual fields are both good measures of the remaining functioning retina in nonsyndromic retinitis pigmentosa, irrespective of inheritance models and dystrophic patterns.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 3
    ISSN: 1435-702X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract • Background: The variability of the visual function impairment in dominant optic atrophy (DOA) makes it difficult to diagnose the disease within genealogies. Physiologic investigations were conducted on a family with DOA to evaluate methods of detecting clinical and subclinical signs in obligate heterozygotes, in order to identify affected subjects within the genealogy and to formulate the individual and reproductive risks • Methods: Investigations included tests for color vision, contrast sensitivity function (CSF), kinetic and static computerized perimetry, transient pattern reversal visual evoked potentials (VEPs) and steady-state flash VEPs • Results: Eight subjects from the pedigree were diagnosed as having DOA. Two of them were unaware of their affection, and six showed wide clinical variability. CSF paralleled the central visual impairment, but was also slightly impaired in the two unaware subjects. Static computerized perimetry disclosed mild sensitivity defects in the central visual fields in these two patients. VEPs showed heteregeneous results as well, ranging from normal findings to severely altered tracings • Conclusions: This investigation suggests that combined clinical and functional evaluation is necessary to diagnose DOA. Particularly, the combined use of computerized perimetry, CSF, and VEPs allowed the identification of cases at a subclinical stage.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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