BACKGROUND: Optic nerve hypoplasia (ONH) has been described as an increasingly 
prevalent cause of congenital blindness. Its association with hypopituitarism 
and absent septum pellucidum has been recognized for more than 40 years as 
"septo-optic dysplasia" or "de Morsier syndrome." More recent studies have 
suggested that these associations are independent of one another. This review 
was designed to assess the historical and recent evidence for associations of 
neuroradiologic, endocrinologic, and developmental problems in patients with 
ONH.
EVIDENCE ACQUISITION: Historical and contemporary literature review.
RESULTS: The medical literature does not support the notion that Georges de 
Morsier ever described a case of ONH or recognized its association with 
hypopituitarism or missing septum pellucidum. Recognition of the critical 
association of ONH with hypopituitarism should be attributed to William Hoyt. 
Hypopituitarism and other more recently identified associations with ONH, such 
as developmental delay, hypothalamic dysfunction, and autism, are independent of 
septum pellucidum development. Other common neuroradiographic associations, such 
as corpus callosum hypoplasia, gyrus dysplasia, and cortical heterotopia, may 
have prognostic significance.
CONCLUSIONS: Children with ONH need to be monitored for many systemic, 
developmental, and even life-threatening problems independent of the status of 
the septum pellucidum. "Septo-optic dysplasia" and "de Morsier syndrome" are 
historically inaccurate and clinically misleading terms that should be 
abandoned.