Nutritional and Toxic Optic Neuropathies

(Toxic Optic Amblyopia; Nutritional Optic Amblyopia)

ByJohn J. Chen, MD, PhD, Mayo Clinic
Reviewed/Revised Oct 2022

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.)


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 is probably undernutrition rather than a toxic effect of alcohol.


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.

Did You Know...

  • Drinking antifreeze (ethylene glycol) or methanol (wood alcohol or methyl alcohol) can cause sudden and complete vision loss.


  • 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.


With prompt treatment, most people with nutritional or toxic optic neuropathy recover some of their lost vision.


  • For undernutrition or alcohol use, vitamin supplements and avoidance of alcohol

  • 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 or drugs that may be toxic. If lead is the cause of toxic optic neuropathy, chelating drugshemodialysis

Magnifiers, large-print devices, and talking watches (low-vision aids) may help people with loss of vision.

Drugs Mentioned In This Article
Test your KnowledgeTake a Quiz!
Download the free Merck Manual App iOS ANDROID
Download the free Merck Manual App iOS ANDROID
Download the free Merck Manual App iOS ANDROID