An upper medial orbital cleft produces a cleft of the medial one-third of the upper eyelid that extends through the eyebrow into the frontal hairline. The skeletal element of the cleft in the region of the frontal process of the maxilla may either pass lateral to the ethmoid, through the supraorbital rim, or it may pass through the ethmoidal labyrinth to produce orbital hypertelorism. This cleft usually accompanies the Number 3 cleft. The soft tissue features include a cleft of the medial portion of the upper eyelid, an irregularity in hair orientation at the medial end of the eyebrow, and a long tongue-like projection of the frontal hairline onto the forehead. There is a mild flattening of the frontal process of the maxilla and extensive pneumatization of both the ethmoidal and frontal sinuses, both of which are more prominent on the cleft side. No bony clefting of the supraorbital rim or frontal bone is evident. The cranial base and sphenoid architecture, including the pterygoid processes, are symmetric and normal. [from
HPO]