Optic nerve hypoplasia (ONH) occurs from the underdevelopment of the optic nerve, which carries neuronal transmission from the retina in the eye to the brain. It is the leading cause of congenital blindness and occurs in approximately 10 in every 100,000 live births. The condition was first described in 1915. Septo-optic dysplasia (SOD) – also known as de Morsier syndrome – is a subtype of ONH and results from underdevelopment of the optic nerve, pituitary gland dysfunction, and absence of the septum pellucidum, which is a midline area of the brain. SOD arises from defects during the embryological development of infants.