Electrical phosphenes: On the influence of conductivity inhomogeneities and small-scale structure of the orbita on the current density threshold of excitation

Electrical and magnetic phosphenes, perceptions of light as a result of non-adequate stimulation of the eye by electrical current or magnetic induction, respectively, are one of the cornerstones to justify limit values for extreme low-frequency fields specified by statutory regulations. However, the...

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Bibliographic Details
Published in:Medical & biological engineering & computing 2002-01, Vol.40 (3), p.354-359
Main Authors: Lindenblatt, G, Silny, J
Format: Article
Language:English
Subjects:
Current density
Electric conductivity
Electric currents
Tissue
Online Access:Get full text
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Summary:Electrical and magnetic phosphenes, perceptions of light as a result of non-adequate stimulation of the eye by electrical current or magnetic induction, respectively, are one of the cornerstones to justify limit values for extreme low-frequency fields specified by statutory regulations. However, the mechanism and place of action, as well as the excitation threshold, remain unknown until now. We suggest that the origin of phosphene excitation is the synaptic layer of the eye. The current density threshold value for electrical phosphene excitation was numerically quantified for this area on the basis of a detailed geometrical model in original submillimetre resolution and specifically measured conductivities in the LF range. The threshold values found were 1.8 Am super(-2) at 60 Hz and 0.3 Am super(-2) at 25 Hz. These values are comparable with values of other excitable tissues. It has been shown that the current density threshold for phosphene generation depends on small-scale structures not taken into account by previous models.
ISSN:0140-0118
DOI:10.1007/BF02344219