magnetophosphene magnetophosphene magnetophosphenes are flashes of light (phosphenes) that are seen when one is subjected to a changing magnetic field such as when in an mri. this changing field causes current within the retina or visual cortex resulting in the illusion of light. in one series, 8 out of 1023 people having an mri experienced flashing lights. magnetophosphenes have been proposed as an explanation for ball lightning.