The photomyoclonic reflex: An artefact in the clinical electroretinogram

M. A. Johnson, R. W. Massof

Research output: Contribution to journalArticlepeer-review


An artefact may appear in the clinical electroretinogram (ERG) that can interfere with the recording and interpretation of the ERG b wave. This artefact, the photomyoclonic reflex (PMR), was studied by covering the eye containing the recording electrode and stimulating the fellow eye. Records obtained by this technique before and after administration of a modified Van Lint lid block demonstrated that most of the PMR is due to a reflex contraction of the orbicularis muscle. The remaining part of the PMR was ascertained by eye movement recordings to be a 1.5° to 3.5° downward and medial eye movement. In most persons the PMR occurs with a latency that is fast enough (59 ms±7 ms) to interfere with interpretation of the b wave under most conditions. The PMR can be minimised in some cases by habituation or conditioned suppression. However, these methods generally do not extinguish the PMR but reduce it enough so that it would not readily be rejected as artefact. In such cases the PMR may produce a wave form that mimics a normal-amplitude ERG but with delayed implicit time.

Original languageEnglish (US)
Pages (from-to)368-378
Number of pages11
JournalBritish Journal of Ophthalmology
Issue number6
StatePublished - 1982

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems
  • Cellular and Molecular Neuroscience


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