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Kenneth R. Alexander, Gerald A. Fishman, Claire S. Barnes, Sandeep Grover; ON-Response Deficit in the Electroretinogram of the Cone System in X-Linked Retinoschisis. Invest. Ophthalmol. Vis. Sci. 2001;42(2):453-459.
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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
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