December 16, 1997An episode of Pokémon, "Dennō Senshi Porygon", aired in Japan induces seizures in 685 Japanese children.
Twenty minutes into the episode, there is a scene in which Pikachu stops vaccine missiles with its Thunderbolt attack, resulting in a huge explosion that flashes red and blue lights. Although there were similar parts in the episode with red and blue flashes, an anime technique called "paka paka" made this scene extremely intense,for these flashes were extremely bright strobe lights, with blinks at a rate of about 12 Hz for approximately four seconds in almost fullscreen, and then for two seconds outright fullscreen. At this point, viewers started to complain of blurred vision, headaches, dizziness and nausea. Some experienced seizures, blindness, convulsions and loss of consciousness. Japan's Fire Defense Agency reported that a total of 685 viewers - 310 boys and 375 girls - were taken to hospitals by ambulances. Although many victims recovered during the ambulance trip, more than 150 of them were admitted to hospitals. Two people remained hospitalized for more than two weeks. Some other people had seizures when parts of the scene were rebroadcast during news reports on the seizures. Only a small fraction of the 685 children treated were diagnosed with photosensitive epilepsy.