Nutritional and toxic optic neuropathies are damage to the optic nerve caused by undernutrition (nutritional optic neuropathies) or by exposure to a substance that is harmful to the optic nerve (toxic optic neuropathies), such as lead, methanol (wood alcohol or methyl alcohol), ethylene glycol (antifreeze), or certain drugs.
A nutritional deficiency or toxic substance is sometimes the cause of optic neuropathy.
Vision usually deteriorates gradually.
People should avoid further exposure to toxic substances or take nutritional supplements.
(See also Overview of Optic Nerve Disorders.)
Visababishaji vya Neuropathi ya Macho Itokanayo na Lishe na Sumu
An optic neuropathy that is caused by a nutritional deficiency (especially of vitamins B1 and B12 or folate [folic acid; see also Overview of Vitamins]) is called nutritional optic neuropathy. People who have had bariatric (weight-loss) surgery and those with alcohol use disorder are particularly susceptible to nutritional optic neuropathy. The actual cause in people with alcohol use disorder is probably undernutrition rather than a toxic effect of alcohol.
Rarely, optic neuropathy is caused by medications (such as chloramphenicol, isoniazid, ethambutol, and digoxin) or toxins such as lead, ethylene glycol (antifreeze), or methanol (wood alcohol or methyl alcohol). When caused by a substance, drug, or toxin, the disorder is called toxic optic neuropathy.
Dalili za Neuropathi ya Macho Itokanayo na Lishe na Sumu
In people with nutritional or toxic optic neuropathies, vision usually deteriorates gradually over days to weeks. A blind spot may develop and gradually enlarge, usually involving the center of vision. It may not be noticed at first. Color vision may be affected more severely than the loss of visual acuity (sharpness of vision). Both eyes are usually affected.
Ethylene glycol and particularly methanol poisoning can cause sudden, complete loss of vision. Both substances can cause other serious symptoms such as coma, difficulty breathing, vomiting, and abdominal pain.
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Utambuzi wa Neuropathi ya Macho Itokanayo na Lishe na Sumu
A doctor's evaluation and sometimes testing
Doctors base the diagnosis of nutritional or toxic neuropathy on the person's history of undernutrition or exposure to toxic or chemical substances, their eye symptoms, and the results of a vision test. Sometimes testing for toxins or for a vitamin deficiency is done.
Matibabu ya Neuropathi ya Macho Itokanayo na Lishe na Sumu
For undernutrition or alcohol use, vitamin supplements and avoidance of alcohol
Treatment of drug or toxin causes (such as chelating drugs for lead or hemodialysis and fomepizole for ethylene glycol or methanol)
Low-vision aids
If alcohol use or undernutrition is the cause of optic neuropathy, the person should stop drinking alcohol, eat a well-balanced diet, and take vitamin supplements that include folate and B vitamins. However, if the cause is mainly vitamin B12 deficiency, treatment with dietary supplements alone is not enough. Vitamin B12 deficiency is typically treated with injections of vitamin B12.
People with toxic optic neuropathies should avoid alcohol and other chemicals, medications, or drugs that may be toxic. If lead is the cause of toxic optic neuropathy, chelating drugs (such as succimer or dimercaprol) help remove it from the body. If ethylene glycol or methanol poisoning is the cause, rapid treatment with hemodialysis to remove these toxins and the antidote drug fomepizole may help. Ethyl alcohol (sometimes called ethanol, grain alcohol, or just alcohol) may also help by decreasing the conversion of the toxin (ethylene glycol or methanol) to a harmful byproduct.
Magnifiers, large-print devices, and talking watches (low-vision aids) may help people with loss of vision.
Utabiri wa Neuropathi ya Macho Itokanayo na Lishe na Sumu
With prompt treatment, most people with nutritional or toxic optic neuropathy recover some of their lost vision.
