Home Conditions A–Z Toxic and nutritional optic neuropathy
Toxic and nutritional optic neuropathy
When medicines, toxins, or low vitamin levels affect the optic nerves
Same-day care
Sudden vision loss in one eye needs same-day care.
Call an eye doctor or go to the emergency department.
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For patients and families
What it is
Certain medicines, toxins, and shortages of key nutrients can damage the optic nerves. It usually affects both eyes at about the same time, without pain.¹ ²
Symptoms
- Gradual blurring of central vision in both eyes
- Colors looking faded, especially red
- Trouble reading or recognizing faces
Common causes
- Medicines, such as ethambutol (for tuberculosis) and linezolid (an antibiotic), among others¹
- Methanol poisoning, for example from contaminated alcohol, which is a medical emergency¹
- Low levels of vitamin B12, folate, thiamine (B1), or copper, which can happen with poor diet, heavy alcohol use, some digestive conditions, or after weight-loss (bariatric) surgery²
Why it matters
When the cause is found early and removed or corrected, vision may improve. Long-standing damage may be permanent.¹ ² Do not stop a prescribed medicine on your own. Call the doctor who prescribes it and your eye doctor.
Weight loss, GLP-1 medicines, and nutrition
GLP-1 medicines can reduce appetite. It is not known whether weight loss with these medicines raises the risk of nutritional optic neuropathy, and we are not aware of studies showing that it does. As a general health step, eat a balanced diet while losing weight and ask your doctor whether you need vitamin checks or supplements.
Dr. Deom’s recommendation (clinical opinion / practice recommendation)
Dr. James Deom recommends that everyone starting or taking a GLP-1 medication have a comprehensive dilated eye exam with OCT, OCT angiography (OCTA), and retinal photography (fundus photos with autofluorescence) as a baseline and for follow-up, and seek same-day care for sudden vision loss.
This is his clinical opinion, not a formal rule from every professional group. AAO and NANOS do not recommend an eye exam only to predict NAION, and no test can reliably predict or prevent it. Dr. Deom recommends the baseline so there is a record to compare against if anything changes, and so other eye problems can be found early.
Dr. James Deom’s personal clinical thought
This is his opinion, not established evidence. It is not a finding from the studies or a position of the FDA, EMA, AAO, NANOS, or AOA.
As people lose weight and get healthier on GLP-1 medicines, their blood pressure and cholesterol medicines are often not reviewed or adjusted. Blood pressure treatment that is no longer matched to a person’s needs may lead to low blood pressure (hypotension). Low blood pressure can be more pronounced at night and could reduce blood flow to the optic nerve during sleep. That possibility would fit the typical way NAION presents: vision loss noticed on waking.
Dr. Deom recommends that people taking a GLP-1 medicine also work on exercise and diet, and keep regular visits with their usual doctors — even if that doctor did not prescribe the GLP-1 — so the rest of their care, including blood pressure, is maintained. Do not start, stop, or change a blood pressure or cholesterol medicine on your own; talk with the clinician who prescribes it.
For clinicians
- Presentation: bilateral, symmetric, painless, progressive loss of central vision with dyschromatopsia and central or cecocentral scotomas; discs normal or hyperemic early and temporally pale later.¹ ²
- Drugs: ethambutol (dose- and duration-related), linezolid, and others; amiodarone-associated optic neuropathy is described but distinguishing it from NAION is debated.¹ ATS/CDC/IDSA tuberculosis guidance calls for baseline visual acuity and color testing and monthly questioning about visual symptoms during ethambutol therapy.³
- Toxins: methanol (emergency; metabolic acidosis), ethylene glycol, and others.¹
- Nutritional: B12, folate, thiamine, and copper deficiency; risk settings include bariatric surgery, malabsorption, alcohol use disorder, and restrictive diets.² Check B12 (with methylmalonic acid), folate, copper, and zinc as indicated.
- GLP-1 RA context: no established link between GLP-1 RA-associated weight loss and nutritional optic neuropathy is known to us. Consider nutritional causes in any bilateral, symmetric central loss, as in any patient with reduced intake.
- Differentials: LHON, compressive lesions, and bilateral optic neuritis.
Dr. Deom’s recommendation (clinical opinion / practice recommendation)
Dr. James Deom recommends that everyone starting or taking a GLP-1 medication have a comprehensive dilated eye exam with OCT, OCT angiography (OCTA), and retinal photography (fundus photos with autofluorescence) as a baseline and for follow-up, and seek same-day care for sudden vision loss.
This is his clinical opinion and practice recommendation, not a society mandate. AAO and NANOS do not recommend routine examination solely to predict NAION, and no exam or imaging test reliably predicts or prevents an acute event. The baseline is intended to document disc anatomy and retinal status for later comparison and to detect other eye disease. See the study comparison for where professional positions agree and differ.
Dr. James Deom’s personal clinical thought
This is his opinion, not established evidence. It is not a finding from the studies or a position of the FDA, EMA, AAO, NANOS, or AOA.
As patients lose weight and their overall health improves on GLP-1 medicines, blood pressure and cholesterol medicines are often not re-addressed. Over-treatment of blood pressure may lead to hypotension, which can worsen at night and could cause nighttime hypoperfusion of the optic nerve. That sequence would fit the typical presentation of NAION (vision loss noticed on waking).
He recommends that people on GLP-1 medicines also improve exercise and diet, and keep regular visits with their usual doctors, even if that clinician did not prescribe the GLP-1, so the rest of their care, including blood pressure, is maintained.
For prescribers: consider reviewing antihypertensive dosing and timing (including bedtime dosing) as weight drops. Coordinate changes with the patient’s usual clinician when someone else wrote the GLP-1 prescription.
How to reach us
Same-day evaluation: providers can call the office at 570-453-2020 (fax 570-453-1020), or refer a patient or ask a question by email. Patients can schedule an exam online.
For privacy, please don’t include patient names or other identifying details in email. Our team will call to schedule and gather details securely.
General contact and referrals: Hazleton Eye Specialists, phone 570-453-2020, fax 570-453-1020. See Referral information for what to send.
References
- Grzybowski A, et al. Toxic optic neuropathies: an updated review. Acta Ophthalmol. 2015;93(5):402-410. https://pubmed.ncbi.nlm.nih.gov/25159832/
- EyeWiki (American Academy of Ophthalmology). Nutritional Optic Neuropathy. https://eyewiki.org/Nutritional_Optic_Neuropathy
- Nahid P, et al. Official American Thoracic Society/Centers for Disease Control and Prevention/Infectious Diseases Society of America clinical practice guidelines: treatment of drug-susceptible tuberculosis. Clin Infect Dis. 2016;63(7):e147-e195. Executive summary: https://pubmed.ncbi.nlm.nih.gov/27621353/
How to reach us
Hazleton Eye Specialists: phone 570-453-2020, fax 570-453-1020. Addresses for all five offices (Hazleton, Stroudsburg, Nanticoke, Pottsville, and Bangor) are on Find an Eye Doctor.
Sudden vision loss needs same-day care. Call an eye doctor right away. If you also have a new headache, jaw pain when chewing, scalp tenderness, fever, or you are over 50 and feel unwell, go to the emergency department.
Medical disclaimer. This page is for general education. The patient section is not medical advice, and the clinician section is not a clinical practice guideline; neither replaces an examination, clinical judgment, or specialty consultation. If you have sudden vision loss, seek same-day care from an eye doctor or an emergency department. Information is current as of the “last reviewed” date.