Patient M was a 25-year-old soldier fighting on the Republican side of the Spanish Civil War. In May 1938, he was shot in the head during a battle. The bullet entered through the right side of his skull and exited through the left.
Patient M was transported to a hospital, where he was admitted to the care of Dr. Justo Gonzalo Rodríguez-Leal. Dr. Rodríguez-Leal was a neurologist who was interested in studying the effects of brain injuries. He kept detailed notes on Patient M's case, which have been invaluable to researchers studying the brain.
When Patient M woke up from his coma, he had lost much of his vision. What little vision he did have was reversed. People and objects appeared on the opposite side of his field of vision. He could read numbers and letters both forward and backwards, and he perceived things in duplicate or triplicate. Sometimes, colours appeared outside of the objects to which they belonged.
In one case, Patient M described seeing men walking upside-down on scaffolding. In another case, he was able to read a newspaper with ease regardless of which way round it was.
Dr. Rodríguez-Leal did not prescribe any specific treatment for Patient M's condition. Instead, he observed Patient M over time and documented his symptoms. Patient M's vision eventually improved somewhat, but he never fully recovered. He continued to see the world backwards for the rest of his life.