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Joost Felius, William H. Swanson; Photopic Temporal Processing in Retinitis Pigmentosa. Invest. Ophthalmol. Vis. Sci. 1999;40(12):2932-2944.
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purpose. The relation between early changes in the photopic flicker
electroretinogram (ERG) and photopic psychophysical changes in
retinitis pigmentosa (RP) is poorly understood. Here, abnormalities in
foveal and extrafoveal temporal contrast sensitivity functions (TCSFs)
were studied in a group of carefully selected patients with RP who had
relatively preserved macular function. The psychophysical results were
compared with changes in the timing of the multifocal ERG.
methods. Subjects were patients with RP who had acuity ≥20/32 and no visual
field defects within 6° from the fovea. Maxwellian-view and
direct-view optical systems were used to obtain foveal and extrafoveal
TCSFs under a range of test conditions, including high retinal
illuminances that yielded temporal contrast sensitivity independent of
mean retinal illuminance. TCSFs were described using log sensitivity
and corner frequency parameters.
results. Foveal TCSFs in these patients showed overall reductions in sensitivity
but no frequency-dependent defects. Also, no macular defects were found
in the timing of the multifocal ERG. TCSFs from extrafoveal locations
in moderate field defects, obtained at retinal illuminances that were
sufficient to render flicker sensitivity independent of effective mean
luminance, showed reductions in overall sensitivity as well as changes
in temporal tuning. The multifocal ERGs from these extrafoveal
locations showed signs of temporal slowing.
conclusions. Changes in temporal tuning (both psychophysical and
electroretinographic) were found only within visual field scotomas,
whereas changes of the log sensitivity parameter were found also in the
relatively preserved foveas of this group of patients with early stage
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