Photic- and pattern-induced seizures: expert consensus of the Epilepsy Foundation of America Working Group.
OBJECTIVE
In August, 2004, the Epilepsy Foundation of America convened a workshop to begin to develop an expert consensus on photosensitive seizures.


METHODS
Literature and data were reviewed, and consensus was derived from discussion.


RESULTS
A flash is a potential hazard if it has luminance >or=20 cd/m2, occurs at a frequency of >or=3 Hz, and occupies a solid visual angle of >or=0.006 steradians (approximately 10% of the central visual field or 25% of screen area at typical viewing distances). A transition to or from saturated red also is considered a risk. A pattern with the potential for provoking seizures contains clearly discernible stripes, numbering more than five light-dark pairs of stripes in any orientation. When the light-dark stripes of any pattern collectively subtend at the eye from the minimal-expected viewing distance a solid angle of >0.006 steradians, the luminance of the lightest stripe is >50 cd/m2, and the pattern is presented for >or=0.5 s, then the pattern should display no more than five light-dark pairs of stripes, if the stripes change direction, oscillate, flash, or reverse in contrast; if the pattern is unchanging or smoothly drifting in one direction, no more than eight stripes. These principles are easier to apply in the case of fixed media, for example, a prerecorded TV show, which can be analyzed frame-by-frame, as compared with interactive media.


CONCLUSIONS
A consensus view of stimuli likely to provoke visually evoked seizures can be developed.
Harding
Graham
G
Clinical Neurophysiology Unit, Aston University, Birmingham, UK.
Wilkins
Arnold J
AJ
Erba
Giuseppe
G
Barkley
Gregory L
GL
Fisher
Robert S
RS
D016288:Computer Terminals / Q000592:standards; D020195:Epilepsy, Reflex / Q000175:diagnosis* / Q000209:etiology; D006801:Humans; D008027:Light / Q000009:adverse effects; D010364:Pattern Recognition, Visual / Q000502:physiology; D010775:Photic Stimulation / Q000009:adverse effects / Q000379:methods*; D013690:Television / Q000592:standards; D006113:United Kingdom