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Karen Holopigian, William Seiple, Vivienne C. Greenstein, Donald C. Hood, Ronald E. Carr; Local Cone and Rod System Function in Patients with Retinitis Pigmentosa. Invest. Ophthalmol. Vis. Sci. 2001;42(3):779-788.
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purpose. To compare local cone and rod system function in patients with retinitis
pigmentosa (RP) using electrophysiological and psychophysical
methods. Cone-mediated multifocal electroretinograms (M-ERGs), cone system
threshold visual fields, rod-mediated M-ERGs, and rod system threshold
visual fields were measured in seven patients with RP.
results. All the patients had normal cone system visual field thresholds and
normal cone-mediated M-ERG implicit times within the central 5°. Both
cone-mediated responses were abnormal at some peripheral retinal
locations. There were significant correlations among cone system
amplitude, timing, and visual field loss. All the patients had some
retinal areas where the rod-mediated M-ERG amplitudes were not
measurable. In areas where they were measurable, these rod-mediated
M-ERG responses were often within normal limits for amplitude and
timing. In contrast to the cone system data, there were no significant
relationships between rod-mediated M-ERG measures and rod system
threshold elevations. The cone and rod system psychophysical thresholds
showed regional correspondence; the amplitude-scale and time-scale
measures of the M-ERG did not.
conclusions. The results indicate that there was better local correspondence between
psychophysical and electrophysiological measures in the cone system
than in the rod system in patients with RP. In addition, the
psychophysical measures of cone and rod system function showed better
correspondence than did the electrophysiological
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