Colour and photosensitive epilepsy.

In this study we relate our experience in 7 cases of photosensitive epilepsy and the effect of different types of filters upon the photoconvulsive response (PR). The study was performed with an 8 channels electroencephalograph and the patients were stimulated with a Joule lamp (1 c/sec-30 c/sec). Red, yellow, blue and green cellophane paper filters were used. The EEG response presented bilateral spikes or polyspikes and slow wave paroxysmal discharges. In the presence of a blue filter, the PR appeared later: an average of 6 seconds of closing the eyes and the response had a lower amplitude. In addition the PR did not appear or it was blocked when we used a double blue filter. These results support the role of the retina in the genesis of the PR. We suggest that the blue filter allows a small percentage of light transmission and under these conditions the electrical events that follow light stimulation do not occur.