Optic Nerve Hypoplasia

Congenital optic nerve hypoplasia (ONH) is a condition in which one or both optic nerves are not fully developed, giving the appearance of abnormally small, pale optic nerve heads upon fundus examination (AAPOS, n.d.). In comparison to the size of the disc, the retinal blood vessels appear larger than normal, when in actuality the vasculature is of normal caliber (Kaur et al, 2013). This non-progressive developmental abnormality is typically characterized by a combination of neurological, behavioral, endocrine, and visual impairments without predilection for a particular sex, race, or socio-economic status (Kaur et al; Johnson, 2005). The prevalence of ONH in infants with severe vision loss, including blindness, is approximately 15-25 percent …show more content…
Changes in the hormone balance are more common with bilateral cases of ONH and include thyroid, pituitary, adrenal, anti-diuretic hormone and growth hormone deficiencies (Kaur et al). Approximately 75 percent of patients have hypopituitarism due to hypothalamic dysfunction and nearly 33 percent have hyperprolactinemia. Endocrinopathies such as these lead to dysregulation of body temperature and sleep cycles (Garcia-Filion). Neurological disorders include septo-optic dysplasia, anencephaly, cerebral atrophy, basal encephaloceles, corpus collosum hypoplasia, gyrus dysplasia, cysts in the posterior fossa and tumors or lesions disrupting the anterior visual pathway – all of which may contribute to cerebral palsy, autism, or other delays in normal development (Kaur et al, …show more content…
Magnetic Resonance Imaging (MRI) is used to assess the neuroradiologic and endocrinologic status of the patient, which is considered a better indication of ONH than optic disc measurement. Electro-retinograms (ERG), electro-oculograms (EOG), and visual evoked response (VER) testing can also be used to differentiate bilateral ONH, in which ERG and EOG are normal and VER decreased, from other infantile conditions of severe visual impairment (Kaur et