Vision loss develops in childhood or adolescence and affects both eyes.
People may also have abnormal heart or nervous system function.
Diagnosis is by a doctor's evaluation and sometimes confirmed by genetic testing.
The disorders cannot be reversed, but measures are taken to aid vision.
(See also Overview of Optic Nerve Disorders Overview of Optic Nerve Disorders The small photoreceptor cells of the retina (the inner surface at the back of the eye) sense light and transmit impulses to the optic nerve. The optic nerve from each eye carries impulses to... read more .)
Causes of Hereditary Optic Nerve Disorders
Dominant optic atrophy and Leber hereditary optic neuropathy are inherited disorders caused by abnormal genes. Both disorders are uncommon, particularly Leber hereditary optic neuropathy.
Dominant optic atrophy is inherited from the mother or father as a dominant gene Dominant disorders Genes are segments of deoxyribonucleic acid (DNA) that contain the code for a specific protein that functions in one or more types of cells in the body. Chromosomes are made of a very long strand... read more , meaning that only one copy of the gene is required for the disorder to develop. In other words, if either the father or the mother has the disease, then each child has a 50% chance of developing it.
Leber hereditary optic neuropathy is inherited through the mother only, because the abnormal genes are located in the mitochondria Mitochondrial chromosomes Genes are segments of deoxyribonucleic acid (DNA) that contain the code for a specific protein that functions in one or more types of cells in the body. Chromosomes are structures within cells... read more . Mitochondria are structures in cells that provide energy for the cell and have their own internal genes that are inherited from only the mother. Affected men cannot pass the disease on to their children. Leber hereditary optic neuropathy is more common among males.
Symptoms of Hereditary Optic Nerve Disorders
In dominant optic atrophy, vision loss begins before the age of 10 years. Some people can also have nystagmus (a rapid jerking movement of the eyes in one direction alternating with a slower drift back to the original position), hearing loss, or both. People also have trouble distinguishing shades of blue and yellow.
In Leber hereditary optic neuropathy, vision loss usually begins between the ages of 15 and 35. Some people have abnormal heart conduction or nervous system function.
Diagnosis of Hereditary Optic Nerve Disorders
A doctor's evaluation
Sometimes genetic testing
Diagnosis is by a doctor's evaluation. Testing can identify some of the abnormal genes responsible for the disorders but not all. People who may have Leber hereditary optic neuropathy undergo electrocardiography to assess their heart.
Treatment of Hereditary Optic Nerve Disorders
There is no effective treatment, but new treatments are being studied. Limiting consumption of alcohol, which may affect the mitochondria, and not using tobacco products may help slow the rate of vision loss.
Magnifiers, large-print devices, and talking watches (low-vision aids) may help people with loss of vision.
Genetic counseling should be considered.
People who have heart or nervous system problems are sent to specialists.