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Optic Nerve Hypoplasia Pediatric Visual Diagnosis Fact Sheet™

Reprinted with permission from Blind Babies Foundation

Definition

Optic Nerve Hypoplasia (ONH) refers to the underdevelopment of the optic nerve during pregnancy. The dying back of optic nerve fibers as the child develops in utero is a natural process, and ONH may be an exaggeration of that process. ONH may occur infrequently in one eye (unilateral) but more commonly in both eyes (bilateral). ONH is not progressive, is not inherited, and cannot be cured. ONH is one of the three most common causes of visual impairment in children.

Causes

In most cases there is no known cause of ONH. Infrequently ONH has been associated with maternal diabetes, maternal alcohol abuse, maternal use of anti-epileptic drugs, and young maternal age (20 years of age or less), but these factors account for very few of the total number of cases. All races and socioeconomic groups seem to be affected by ONH.

Characteristics

Diagnosis

ONH is diagnosed by direct examination of the eye by an ophthalmologist. No current laboratory or radiographic tests will establish the diagnosis. Many infants who are diagnosed with Optic Nerve Atrophy are, in fact, children with ONH. Sometimes visual functioning can be predicted from the appearance of the optic discs. However, it is very difficult to predict visual acuity on this basis alone.

Visual and Behavioral Characteristics

Conditions Associated With ONH

Associated brain and hormonal abnormalities are common in children with nystagmus and bilateral severe vision loss, and are less common in cases where vision loss is mild or unilateral. Abnormalities include:

  1. Midline anomalies of the brain: septo optic dysplasia (absence of the septum pellucidum and the corpus callosum), encephaloceles, anomalies of the ventricles, anencephaly, cerebral atrophy, and rarely, tumors.
  2. Hormonal insufficiencies: thyroid, growth hormone, pituitary, adrenal, anti-diuretic hormone (ADH).

Associated midline brain anomalies can be identified by either an MRI or CT scan. Hormonal insufficiencies require an examination by a specialist in hormonal disorders (pediatric endocrinologist). Children particularly at risk for having associated hormonal insufficiencies are those who had neonatal low blood sugar (hypoglycemia), had prolonged jaundice (hyperbilirubinemia), failed to grow normally (failure to thrive), have difficulty regulating body temperature in connection with viral illnesses, and/or had a CT or MRI scan showing an absence of tissue connecting the brain to the pituitary gland (the pituitary stalk).

Myths

The following statement are NOT TRUE according to current research:

Teaching Strategies

Glossary

  1. Amblyopia: a reversible condition affecting visual acuity that can lead to loss of vision in an eye that is structurally capable of seeing.
  2. Anencephaly: a birth defect in which all but the most primitive part of the brain, spinal cord, and overlying bones of the skull are absent.
  3. Corpus Callosum: a mass of white matter that joins the cerebral hemispheres of the brain, allowing them to communicate with each other.
  4. Encephalocele: a birth defect in which the brain protrudes through an opening in the skull.
  5. Perinatal: describes the period between 28 weeks gestation through the first week following delivery.
  6. Radiographic: refers to a picture produced on a sensitive surface by a form of radiation other than light.
  7. Septo optic dysplasia: a syndrome which includes midline abnormalities of the brain and optic nerve hypoplasia.
  8. Visual Acuity: ability of the eye to see clearly (which can be measured specifically), to perceive objects and to see detail within central vision.

Resources

Borchert, M.S. An Inside Look At Optic Nerve Hypoplasia Research - A Leading Cause of Infant Blindness, USC School of Medicine.

Hoyt. C. (1986). Optic Nerve Hypoplasia: A Changing Perspective. Transactions of the New Orleans Academy of Ophthalmology. Raven Press, New York.

Lambert, S. & Hoyt, C. (1987). Optic Nerve Hypoplasia. Ophthalmology. 32, #1, July, August, 1-9.

Marsh-Tootle, W.L. (1994). Congenital Optic Nerve Hypoplasia: A Symposium Paper. Optometry & Vision Science. 71; #3, 174-180.

Tait, P. (1989). Optic Nerve Hypoplasia: A Review of the Literature, Journal of Visual Impairment and Blindness, April, 207-211.

Willnow, S. et al. (1996). Endocrine disorders in septo-optic dysplasia (De Morsier syndrome)-evaluation and follow up of 18 patients. European Journal of Pediatrics, 155; 179-184.

Acknowledgments

Project Coordinators: Julie Bernas-Pierce, M.Ed. and Namita Jacob, Dr. Creig Hoyt, Nancy Akeson, Gail Calvello, Laila Adle, Carole Osselaer, Patricia Silva, Laura Davis. Reviewers: Kay Ferrell, Ph.D., Deborah Hatton, Ph.D., Kathryn Nael Manalo

The Pediatric Visual Diagnosis Fact Sheets are sponsored by a grant from the Blind Childrens Center and with support from the Hilton/Perkins Program through a grant from the Conrad Hilton Foundation of Reno, Nevada. REPRODUCTION FOR RESALE IS STRICTLY PROHIBITED (1/98 BBF)

Blind Babies Foundation
1200 Gough Street
San Francisco, California 94109
(415) 771-5464

Editor's note: Blind Babies Foundation has developed 7 Pediatric Visual Diagnosis Fact SheetsTM on the following topics: Cortical Visual Impairment, Retinopathy of Prematurity, Optic Nerve Hypoplasia, Albinism, Optic Nerve Atrophy, Retinal Diseases, and Vision Assessment. One complete set costs $10. Families can get one Fact Sheet free of charge upon request. The Blind Childrens Center will have the Fact Sheets available soon on their website at www.blindcntr.org/bbc.


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Last Revision: October 31, 2005