Floor of the median orbit in human cyclopia: an anatomical study in three dimensions.

A three dimensional study has been undertaken of the floor of the median orbit in human cyclopia. The cyclopic material consists of a full term desiccated head, a dried fetal skull and four sectioned fetal heads. Most elements in the floor of the median orbit are normal. Such abnormalities as are present in the bony floor and the related lacrimal sac are considered to be secondary to the absence of the presphenoid and the postero-inferior part of the nasal cavity. The abnormalities seen in the medial and inferior rectus muscles are considered to be secondary to the absence of a medial orbital wall and normally defined and directed optic nerves and eyeballs.