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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Documenta ophthalmologica 88 (1994), S. 27-37 
    ISSN: 1573-2622
    Keywords: Electroretinogram ; Electrophysiology ; Retinitis pigmentosa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-2622
    Keywords: Electroretinogram ; Kinetic perimetry ; Psychophysics ; Retinitis pigmentosa ; Visual field
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
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