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J.E. Lee, R.K. Imes, R.L. Stamper, M. Wang, E.E. Sutter; A Comparison of mfERG with mfVEP for the Evaluation of Optic Nerve Function . Invest. Ophthalmol. Vis. Sci. 2003;44(13):4100.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose To compare techniques of optic nerve evaluation, using multifocal ERG with analysis of the optic nerve head component (ONHC) and multifocal VEP. Methods Several patients with suspected optic nerve dysfunction were selected to illustrate a variety of potential applications. One patient had glaucomatous visual field loss with a deep peripheral scotoma in one eye. A patient with good visual function had unilateral optic nerve glioma. Another patient had unilateral vision loss attributed to a presumed shrapnel injury to the orbit. MfERG was performed using a m-sequence protocol, with analysis of 1st and 2nd order kernels. An additional mfERG protocol with interleaved periodic global flashes was performed, and the ONHC was extracted. MfVEP was performed using a pattern reversal stimulus. Results In a patient with glaucoma, mfERG revealed normal 1st and 2nd order kernels, and the ONHC was globally reduced by 75%. The ONHC was reduced below the level of detection in a focal region corresponding to a deep peripheral scotoma. In a patient with optic nerve glioma, mfERG revealed normal 1st and 2nd order kernels, and the ONHC was greatly reduced in the eye with pathology. Interocular comparison of mfVEPs revealed a focal region of amplitudes reduced by 66% and implicit times delayed by 10-20 ms. In a patient with presumed shrapnel injury to the orbit, mfERG revealed normal 1st and 2nd order kernels, and the ONHC was also normal. Reduced visual function was confirmed by mfVEP revealing low amplitudes (<18nV/deg) in the region corresponding to central vision. Conclusions In glaucoma, ONHC analysis detected a focal region with large reductions of ganglion cell function in the peripheral visual field, in addition to moderate reductions globally. With optic nerve glioma, ONHC analysis detected a reduction of ganglion cell function, and mfVEP detected focal changes in amplitude and implicit time. With a presumed shrapnel injury to the orbit, ONHC analysis suggested normal ganglion cell function to indicate a possible alternative mechanism of visual loss. MfVEP can quantitatively assess focal changes in visual function that may correlate with optic nerve function in selected cases. MfERG with ONHC analysis can assess optic nerve involvement by directly measuring ganglion cell function.
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