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SM Shuwairi, K Holopigian, VC Greenstein, X Zhang, DC Hood; Multifocal Visual Evoked Potentials to Cone Specific Stimuli in Patients with Retinitis Pigmentosa (RP) . Invest. Ophthalmol. Vis. Sci. 2002;43(13):1172.
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Purpose: To examine whether the multifocal visual evoked potential (mfVEP) to cone specific stimuli in patients with RP supplies additional information not available in the multifocal electroretinogram (mfERG) or visual fields. Methods: RP patients were enrolled based on the following criteria: visual acuity of 20/25 or better and central visual fields of at least 10 degrees. Monocular mfVEPs were obtained to a pattern reversing display that modulated only the L- or M-cones. The mfVEP display was a scaled, 60 sector, dartboard array 44 degrees in diameter. Electrodes were placed at the inion, 4 cm above, and at 1 cm above and 4 cm lateral to the inion on both sides. The cone contrasts were 47% for both the L and M-stimuli. In addition, mfVEPS were recorded to a standard black and white dartboard array. Humphrey visual fields (24-2), color vision tests, and mfERGs were obtained on all patients. The mfERGs were measured using a 46 degree display with 103 scaled black and white hexagons. Results: The correspondence between the mfVEPs and visual field sensitivity was better than the correspondence between mfVEPS and mfERGs. This was true for both chromatic and achromatic mfVEPs. For example, mfVEP responses could not be detected in regions with large mfERG responses and poor visual field sensitivity and there were examples of mfVEP responses in regions with non-detectable mfERGs. However, for a few patients, neither mfERG nor mfVEP responses were detectable in regions with relatively good visual field sensitivity. There was no evidence of color-specific latency or amplitude differences in the mfVEP as has been reported for the mfERG . Conclusion: The mfVEP supplies information about visual function not necessarily seen in the visual field or mfERG. 1. Scholl & Kremers. (2000). IOVS, 41(10).
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