Septo-optic dysplasia (or de Morsier syndrome) is a congenital disorder 
characterised by anomalies in cerebral midline structures, optic nerve 
hypoplasia, and hormonal deficiencies. Diagnosis should be made early, due to 
the possibility of treating the hormonal disturbances. We describe here a case 
with decreased visual acuity, one-sided hemianopia, nystagmus und agenesis of 
the septum pellucidum and discuss the heterogeneous appearance of this syndrome. 
There are two theories regarding its pathogenesis. The first postulates 
simultaneous damage to both cerebral structures and optic nerve development 
around the 6th week of gestation, while the other favours secondary degeneration 
of optic nerve fibres due to a cerebral lesion.