Optic Nerve Atrophy (ONA)
Optic Nerve Atrophy is a permanent visual impairment caused by damage to the optic nerve. The optic nerve functions like a cable carrying information from the eye to be processed by the brain. The optic nerve is comprised of over a million small nerve fibers (axons). When some of these nerve fibers are damaged through disease, the brain doesn’t receive complete vision information and sight becomes blurred.
Atrophy (wasting away) may be partial in which some axons are damaged or profound in which most axons are damaged. A child’s ability to see clearly (visual acuity) is affected due to nerve damage that occurs in the central part of the retina responsible for detail and color vision (macula). These areas of the eye are more vulnerable to the effects of atrophy. ONA is the end result of damage to the optic nerve. It can affect one or both eyes. It may also be progressive, depending on the cause.
Many diseases and conditions may lead to optic atrophy. Tumors of the visual pathway, inadequate blood or oxygen supply (hypoxia ischmia) before or shortly after birth, trauma, hydrocephalus, heredity, and rare degenerative diseases have been identified as causes of ONA. When hereditary, the pattern is dominant. This means that one parent with the condition would pass the gene to 50% of his/her children. If caused by a tumor, the process of ONA may be halted by removal of the tumor.
Additional information is available in the Blind Children’s Center Pediatric Visual Diagnosis Fact Sheets.