All in the timing
- Correspondence to: Dr Bryan J Winn Department of Ophthalmology, UCSF Medical Center, 10 Koret Way, Room K301, San Francisco, CA 94143, USA;bjw15{at}columbia.edu
mfVEP as a measure of perimetry
In this issue of the BJO, the paper by Semela et al1 (see page 445) reports on the characteristics of the multifocal visual evoked potential (mfVEP) in six cases of compressive optic neuropathy (CON) secondary to optic nerve meningiomas. The mfVEP can be thought of as an objective measure of perimetry. With the display used by Semela’s group, the 60 sectors tested comprise about the same area of visual field as the Humphrey 24–2 standard automated perimetry (SAP) test. Unlike SAP, the mfVEP does not require the subject to consciously register and respond to stimuli but rather is generated by the electrical potentials evoked by the individual pattern-reversal stimuli at the primary visual cortex.2 The amplitudes of mfVEPs have been shown to correlate well with SAP in several optic neuropathies including ischaemic optic neuropathy (ION) and glaucoma.2–8 …
