Background: Optic Nerve Hypoplasia (ONH) is a leading cause of blindness in children. For unclear reasons, the incidence of ONH is increasing, with ONH affecting about 1 in 10,000 live-born infants. In addition to visual deficits, ONH is associated with varying degrees of hypopituitarism, developmental delay, brain malformations and obesity. Although genetic mutations have been rarely observed to result in ONH, the causes of ONH are largely not known. In limited anatomical observations, the suprachiasmatic nuclei (SCN) located in the anterior hypothalamus, which generate circadian rhythms, have been observed to be abnormal in children with ONH. Thus, children with ONH may have biological clock dysfunction.