It is a congenital malformation; it presents a single facial orbit due to the failed division in the forebrain during the development of the embryo.
It is very common that there is also a dysfunctional nose, in some cases they may be underdeveloped or in other cases absent, being replaced by a proboscis, usually located in the middle of the face.
The vast majority of those born with cyclopia who manage to survive delivery have other serious defects that would make survival difficult.
