I subscribe to the opinion of Nikolai. Also, ancient Greek scientists put forward a theory that he is just an alien from Mars and at the same time - the god of music on planet Earth. For the sake of his musical talent, he paid with a fork in the eye, or not at all for the sake of talent. This question torments us for many centuries, I transmit it to the RenTV TV channel, I am sure that they will find the answer to this extremely important question.
Bowie's left eye was damaged as a teenager when he got into a fight with school buddy George Underwood over a girl. Underwood touched Bowie's eye (or rather, then - David Jones) with a fingernail and tore the sphincters of the pupil. The pupil has lost the ability to constrict, which gives the visual effect of eyes of different colors (in fact, both eyes are the same in color). In medical parlance, this is called "anisocoria."
It is worth noting that Bowie and Underwood remained friends even after this episode and even played in the same group (before Bowie gained global popularity).