Aim of study (according to author)
The aim of this study was to describe quantitatively the nature of magnetophosphenes (magnetic field-induced phosphenes).
Particular interest has been focused on threshold values and the way in which they are affected by background light.
Time-variable very low frequency (10-50 Hz) electromagnetic fields of moderate magnetic flux densities (0-40 mT) were used.
The study comprised four different test groups: 1) 11 healthy volunteers; phosphene threshold values were determined in darkness as well against background light; 2) 8 healthy subjects; thresholds were recorded at frequencies of 20, 30 and 35 Hz during dark-adaptation; 3) 6 healthy volunteers with normal colour vision; threshold values were recorded with three different background colours; 4) 9 healthy but colour defective subjects; same conditions as for group 3.
General category: magnetic field
| 10 - 50 Hz|
exposure duration: 28 min
|magnetic flux density: 40 mT mean value (0 - 40 mT)|
partial body exposure: head
Main outcome of study (according to author)
Maximum sensitivity occured at a frequency of approximately 20-30 Hz, and with broad-spectrum light the threshold magnetic flux density was 10-12 mT. The threshold values depended upon the intensity and the spectral distribution of the background light. Sensitivity decreased during dark adaptation. In certain respects colour defective volunteers differed from subjects with normal colour vision.
(Study character: medical/biological study, experimental study, full/main study)
Study funded by
© 1997 - 2013, Research Center for Bioelectromagnetic Interaction (femu - RWTH Aachen University, Germany).
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