This document presents the current (2004) standard\ud for the visual evoked potential (VEP). The VEP\ud is an evoked electrophysiological potential that can\ud be extracted, using signal averaging, from the electroencephalographic\ud activity recorded at the scalp. The\ud VEP can provide important diagnostic information\ud regarding the functional integrity of the visual system.\ud The current standard presents basic responses\ud elicited by three commonly used stimulus conditions\ud using a single, midline recording channel with\ud an occipital, active electrode. Because chiasmal and\ud retrochiasmal diseases may be missed using a single\ud channel, three channels using the midline and two\ud lateral active electrodes are suggested when one goes\ud beyond the standard and tests patients for chiasmal\ud and retrochiasmal dysfunction.\ud Pattern reversal is the preferred technique for most\ud clinical purposes. The results of pattern reversal\ud stimuli are less variable in waveform and timing\ud than the results elicited by other stimuli. The pattern\ud onset/offset technique can be useful in the detection of\ud malingering and in patients with nystagmus, and the\ud flash VEP is particularly useful when optical factors\ud or poor cooperation make the use of pattern stimulation\ud inappropriate. The intent of this standard is that\ud at least one of these techniques should be included\ud in every clinical VEP recording session so that all\ud laboratories will have a common core of information\ud that can be shared or compared

Summary: Purpose: Symptomatic visual field constriction thought to be associated with vigabatrin has been reported. The current study investigated the visual fields and visual electrophysiology of eight patients with known vigabatrin‐attributed visual field loss, three of whom were reported previously. Six of the patients were no longer receiving vigabatrin. Methods: The central and peripheral fields were examined with the Humphrey Visual Field Analyzer. Full visual electrophysiology, including flash electroretinography (ERG), pattern electroretinography, multifocal ERG using the VERIS system, electro‐oculography, and flash and pattern visual evoked potentials, was undertaken. Results: Seven patients showed marked visual field constriction with some sparing of the temporal visual field. The eighth exhibited concentric constriction. Most electrophysiological responses were usually just within normal limits; two patients had subnormal Arden electro‐oculography indices; and one patient showed an abnormally delayed photopic b wave. However, five patients showed delayed 30‐Hz flicker b waves, and seven patients showed delayed oscillatory potentials. Multifocal ERG showed abnormalities that sometimes correlated with the visual field appearance and confirmed that the deficit occurs at the retinal level. Conclusion: Marked visual field constriction appears to be associated with vigabatrin therapy. The field defects and some electrophysiological abnormalities persist when vigabatrin therapy is withdrawn.

APPC in secondary syphilis can occur even in immunocompetent patients. A high index of suspicion is required for early diagnosis of this condition resulting in a good visual outcome with adequate treatment. mfERG and optical coherence tomography are useful in the diagnosis and follow-up of these patients.

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