Cyclopia is a rare and lethal condition that is characterized by fused orbits, arrhinia and proboscis ¹. It is most commonly seen in association with holoprosencephaly (alobar type) and Patau syndrome (trisomy 13) ³.

In holoprosencephaly due to abnormal development of embryonic forebrain which is responsible for inducing the development of the two orbits, only one orbit is developed. This eye is centrally placed in the area normally occupied by the root of the nose. The proboscis is a non-functioning appendage seen attached to the forehead above the central eye ².

It may sometimes also be associated with cardiac defects (atrial septal defect, hypoplastic left heart, anomalous communication between right ventricle and aorta) ³.

Approximately 1.05 in 100,000 births including stillbirths are identified as cyclopean ⁴.