Optic nerve hypoplasia and septo‐optic‐pituitary dysplasia

Optic nerve hypoplasia (ONH) and septo-optic-pituitary dysplasia (SOD) are diseases in which one or both eye nerves are small. For unclear reasons, more cases are being diagnosed annually. ONH/SOD develop during pregnancy and are the leading cause of poor vision in children. A children's eye specialist can diagnose ONH. There is no cure for the impaired vision caused by the small eye nerves. However, ‘lazy eye’ (known as amblyopia) can also occur in ONH/SOD and impairs vision further. Vision usually improves when amblyopia is treated early. Other brain abnormalities may occur in SOD, such as a small and/or non-functioning gland, called the pituitary gland. A blood test to investigate pituitary gland function and a brain scan (called MRI) are needed to investigate the full extent of ONH/SOD. The risk of developing impaired pituitary gland function continues until completion of puberty, so its function should be checked regularly since missing a poorly functioning pituitary gland may lead to life-threatening crisis or death. Other brain disorders (e.g. epilepsy, cerebral palsy), and psychiatric conditions (e.g. mood or anxiety disorders) may also occur in ONH/SOD. Infrequently, some patients have no sense of smell. The cause for ONH/SOD is mostly unknown. The main risk factors for developing ONH/SOD are maternal smoking during pregnancy, young maternal age at conception, and first pregnancy.