Different eye colour between the eyes
A difference in eye color between the two eyes of a person is medically called iris heterochromia. This can be congenital due to genetic dispositions or genetic mutations. If someone is born with heterochromia, one should clarify whether a syndrome may also be associated with hearing loss.
Furthermore, a difference in eye colour between the right and left iris may be acquired due to trauma to the eye, inflammation of the eye or injuries to the optic nerve. In this case, too, clarification by an ophthalmologist is required. Overall, heterochromia is very rare.
Different eye colour within one eye
About 1% of the world population has different eye colours between the eyes. Subforms of this are sectoral or central heterochromia. Here a person has different colours within one eye.
In the sectoral form only a small part of the iris is spotted differently coloured. In the central form, the colour of the iris is different around the pupil like a ring. If a person has different eye colours within one eye, this does not always have to be a disease, but can simply be congenital. However, in the case of a new occurrence, an examination by an ophthalmologist should always be carried out.