[Prenatal ultrasound measurement of the interorbital distance. Method of recognizing lesser degrees of holoprosencephaly].

The antenatal diagnosis of holoprosencephaly seems to need study of the interhemispheric fissure which may or not be complete in lesser degrees of that disease, but also measuring of interorbital distance (I.O.D.) and I.O.D./B.P.D. (biparietal diameter) ratio. The two last parameters show the constant hypotelorism. These measures may be useful in all fetal congenital deformities which include facial dysmorphy with modification of the interorbital distance.