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  • Title: On-response deficit in the electroretinogram of the cone system in X-linked retinoschisis.
    Author: Alexander KR, Fishman GA, Barnes CS, Grover S.
    Journal: Invest Ophthalmol Vis Sci; 2001 Feb; 42(2):453-9. PubMed ID: 11157882.
    Abstract:
    PURPOSE: The purpose of this study was to evaluate the hypothesis that the reduced b-wave to a-wave ratio of the brief-flash electroretinogram (ERG) of the cone system typically observed in X-linked retinoschisis (XLRS) represents a relatively greater deficit in the ON response (response to light onset) than the OFF response (response to light offset). A second purpose was to investigate the use of sawtooth flicker as a stimulus for eliciting ERG ON and OFF responses. METHODS: Light-adapted, full-field ERGs were recorded in six patients with XLRS and six age-similar control subjects in response to 8-Hz rapid-on and rapid-off sawtooth flicker to emphasize ON and OFF responses, respectively. ERG responses were analyzed in terms of the amplitudes and implicit times of the a-wave, b-wave, and d-wave components. RESULTS: There was no significant difference between the patients with XLRS and the control subjects for either the amplitude of the a-wave of the ON response or the amplitude of the d-wave of the OFF response. However, the amplitude of the b-wave of the ON response was reduced significantly in the patients with XLRS, resulting in a significantly reduced b-wave to d-wave ratio. The patients' implicit times were increased significantly for all waveform components. CONCLUSIONS: The reduced b-wave to d-wave ratio of the ERG of the cone system in these patients with XLRS is consistent with a relative dysfunction of the cone ON bipolar cell pathway in this disorder. The results show further that sawtooth flicker is a promising stimulus for eliciting well-defined ERG waveforms that can provide a quantitative assessment of the properties of ON and OFF responses in retinal disease.
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