Optic nerve hypoplasia in children

Optic nerve hypoplasia (ONH) is a nonprogressive, developmental abnormality of the optic nerve in the eye; ONH is present at birth. The visual result of this condition ranges from minimal visual impairment to total blindness, and it more commonly affects both eyes than just one eye. In many individuals, ONH is not the only eye anomaly. Also, it has been associated with abnormalities of other body systems, including the endocrine and nervous systems. Characteristic of the condition is the presence of a smaller than normal optic nerve. ONH appears to be caused by an insult to the developing optic nerve during pregnancy. It has been associated with maternal diabetes mellitus, young age of the mother, and postmaturity (birth after the fetus is full-term). ONH has been reported in 48 percent of fetal alcohol syndrome babies, and alcohol may be the major teratogenic agent, or substance that causes deformity of the fetus. Impairments in vision vary; patients may have good visual acuity, but have defects in their field of vision. Reactions of the pupil to light frequently are abnormal, indicating an afferent nerve pathway defect. Small size of the optic disc can be seen on careful ophthalmoscopic examination. ONH must be distinguished from farsightedness and optic atrophy. ONH has been associated with septo-optic dysplasia, a condition of abnormal development of the midline of the brain with incomplete development of the optic nerve. Septo-optic dysplasia as well as ONH have been associated with pituitary gland insufficiency. A child with bilateral ONH should be evaluated for possible endocrine and neurologic disorders. (Consumer Summary produced by Reliance Medical Information, Inc.)