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Measurement, management, and the GLP-1 paradox

Reviewed by Dr. James Deom, OD, MPH, FAAO, FSLS, Chief of Eye Care Services, Hazleton Eye Specialists Last reviewed: November 12, 2026 Audience: Patients & public, with a clinician section

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Excess weight matters to the optic nerve mainly through the conditions it is linked with: sleep apnea, high blood pressure, type 2 diabetes, and high cholesterol. Each of these has been associated with NAION in research.¹ ² Losing weight can improve them.³ ⁴ ⁵ At the same time, GLP-1 medicines, which can produce large weight loss, now carry a labeled potential increased risk of NAION.⁶ This page explains both sides.

For patients and families

How weight is measured

  • Body mass index (BMI) is weight in kilograms divided by height in meters squared. For adults: below 18.5 underweight; 18.5 to under 25 healthy weight; 25 to under 30 overweight; 30 or higher obesity (class 1: 30 to under 35; class 2: 35 to under 40; class 3: 40 or higher). BMI is a screening measure and should be considered with other factors.⁷
  • Waist circumference estimates fat around the abdomen. Measure standing, with the tape just above the hip bones, after breathing out. A waist over 40 inches (102 cm) in men or over 35 inches (88 cm) in women is associated with higher risk of type 2 diabetes, high blood pressure, and heart disease, even when BMI is normal.⁸

How excess weight is linked to NAION

Flow diagram. A box labeled excess weight, higher BMI or waist size, has arrows to four boxes: obstructive sleep apnea, high blood pressure, type 2 diabetes, and high cholesterol or triglycerides. Each of those has an arrow to a box labeled higher reported chance of NAION. A note below describes the GLP-1 paradox.
Arrows show associations reported in studies, not proven causes. Original schematic.

Studies of NAION risk factors have mostly measured the conditions that come with excess weight rather than weight itself. In pooled studies, sleep apnea, diabetes, high blood pressure, and high cholesterol were each associated with NAION.¹ ² A group of these together (a large waist, high blood pressure, high blood sugar, high triglycerides, and low “good” HDL cholesterol) is called metabolic syndrome.⁹

Ways to manage weight

  • Diet and activity. A reduced-calorie eating plan, more physical activity, and behavioral support are the foundation, and they help blood pressure and sleep apnea as well.³ ⁵
  • Medicines. GLP-1–based medicines such as semaglutide and tirzepatide, used with diet and activity, produced average weight loss of about 15% to 21% in large trials, compared with about 2% to 3% with placebo.¹⁰ ¹¹ They are prescription medicines with side effects and are not right for everyone.
  • Surgery. Weight-loss (metabolic and bariatric) surgery may be an option for adults with a BMI of 40 or more, or 35 or more with a serious weight-related health problem.¹²

The GLP-1 paradox

Two things are true at the same time: 1. Weight loss improves several NAION risk factors. Blood pressure falls by roughly 1 mm Hg per kilogram lost in trials,³ and sleep apnea improves with weight loss.⁴ ⁵ 2. The GLP-1 medicine class carries a labeled potential risk. In November 2026 the FDA required all GLP-1 receptor agonist labels to add a potential increased risk of NAION.⁶ The European Medicines Agency concluded in 2025 that NAION is a very rare side effect of semaglutide.¹³ The absolute risk is low, and whether the medicine causes NAION is still debated.

This is why Dr. Deom recommends a baseline eye exam and follow-up for people on these medicines, and same-day care for any sudden vision loss.

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.

Practical steps

  • Keep working on diet and activity, whether or not you take a weight-loss medicine.
  • Keep regular visits with your usual doctor, who can recheck blood pressure, blood sugar, and cholesterol medicines as your weight changes.
  • Never stop or change a medicine without talking to the clinician who prescribes it.
  • Tell your eye doctor if you start, stop, or change a GLP-1 medicine.

For clinicians

Measurement

  • CDC adult BMI categories as above; BMI is a screening measure.⁷ NHLBI: waist >102 cm (40 in) in men or >88 cm (35 in) in women raises the risk category by one level for BMI 25–34.9 and is a marker of risk even at normal BMI.⁸
  • Metabolic syndrome (AHA/NHLBI): any three of elevated waist circumference, triglycerides ≥150 mg/dL, reduced HDL (<40 mg/dL men, <50 mg/dL women), BP ≥130/85 mm Hg, fasting glucose ≥100 mg/dL (or drug treatment for the relevant factor).⁹

NAION relevance

  • Pooled estimates: sleep apnea RR 3.28, diabetes RR 1.53, hyperlipidemia RR 1.43, hypertension RR 1.28;¹ in a separate meta-analysis, diabetes OR 1.71, dyslipidemia OR 2.00, hypertension OR 1.50, with higher triglycerides and Lp(a) also associated.²
  • These factors also confound observational studies of GLP-1 RAs and NAION (confounding by indication). See GLP-1 RAs and NAION for absolute-risk figures and the FDA trial meta-analysis.

Management

  • Lifestyle: ATS strongly recommends comprehensive lifestyle intervention (reduced-calorie diet, increased activity, behavioral guidance) for overweight or obese adults with OSA; pharmacotherapy and bariatric surgery for selected patients.⁵
  • Pharmacotherapy: STEP 1, semaglutide 2.4 mg, −14.9% vs −2.4% at 68 weeks;¹⁰ SURMOUNT-1, tirzepatide −15.0% to −20.9% vs −3.1% at 72 weeks.¹¹
  • Surgery: BMI ≥40, or ≥35 with a serious obesity-related condition (NIDDK).¹²
  • As weight falls, reassess antihypertensive, lipid, and glucose-lowering regimens. Rapid A1c lowering has separate retinal implications; see Diabetic retinopathy early worsening.

The GLP-1 paradox, for counseling

Weight loss improves BP, OSA severity, and glycemia, all associated with NAION, while the drug class now carries a labeled potential NAION risk (FDA class labeling, Nov 2026;⁶ EMA PRAC “very rare” for semaglutide¹³). Counsel on the low absolute risk, the warning symptoms, and same-day evaluation, and document a baseline (see Dr. Deom’s recommendation above).

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

  1. Liu B, et al. Risk factors for non-arteritic anterior ischemic optic neuropathy: a large scale meta-analysis. Front Med (Lausanne). 2021;8:618353. https://pubmed.ncbi.nlm.nih.gov/34671609/
  2. Chatziralli I, et al. Cardiometabolic factors and risk of non-arteritic anterior ischemic optic neuropathy: a systematic review and meta-analysis. Graefes Arch Clin Exp Ophthalmol. 2022;260:1445-1456. https://pubmed.ncbi.nlm.nih.gov/35067769/
  3. Neter JE, et al. Influence of weight reduction on blood pressure: a meta-analysis of randomized controlled trials. Hypertension. 2003;42(5):878-884. https://pubmed.ncbi.nlm.nih.gov/12975389/
  4. Peppard PE, et al. Longitudinal study of moderate weight change and sleep-disordered breathing. JAMA. 2000;284(23):3015-3021. https://pubmed.ncbi.nlm.nih.gov/11122588/
  5. Hudgel DW, et al. The role of weight management in the treatment of adult obstructive sleep apnea. An Official American Thoracic Society Clinical Practice Guideline. Am J Respir Crit Care Med. 2018;198(6):e70-e87. https://pubmed.ncbi.nlm.nih.gov/30215551/
  6. U.S. Food and Drug Administration. FDA requires safety labeling changes for GLP-1 RAs due to potential increased risk of a rare but serious eye condition. Drug Safety Communication, Nov 9, 2026. https://www.fda.gov/drugs/drug-safety-communications/fda-requires-safety-labeling-changes-glucagon-peptide-1-receptor-agonists-glp-1-ras-due-potential
  7. Centers for Disease Control and Prevention. Adult BMI categories. https://www.cdc.gov/bmi/adult-calculator/bmi-categories.html
  8. National Heart, Lung, and Blood Institute. Classification of overweight and obesity by BMI, waist circumference, and associated disease risks. https://www.nhlbi.nih.gov/health/educational/lose_wt/BMI/bmi_dis
  9. Grundy SM, et al. Diagnosis and management of the metabolic syndrome: an American Heart Association/National Heart, Lung, and Blood Institute Scientific Statement. Circulation. 2005;112(17):2735-2752. https://pubmed.ncbi.nlm.nih.gov/16157765/
  10. Wilding JPH, et al. Once-weekly semaglutide in adults with overweight or obesity. N Engl J Med. 2021;384(11):989-1002. https://pubmed.ncbi.nlm.nih.gov/33567185/
  11. Jastreboff AM, et al. Tirzepatide once weekly for the treatment of obesity. N Engl J Med. 2022;387(3):205-216. https://pubmed.ncbi.nlm.nih.gov/35658024/
  12. National Institute of Diabetes and Digestive and Kidney Diseases. Weight-loss (metabolic and bariatric) surgery. https://www.niddk.nih.gov/health-information/weight-management/bariatric-surgery
  13. European Medicines Agency, PRAC. PRAC concludes eye condition NAION is a very rare side effect of semaglutide medicines Ozempic, Rybelsus and Wegovy. Jun 6, 2025. https://www.ema.europa.eu/en/news/prac-concludes-eye-condition-naion-very-rare-side-effect-semaglutide-medicines-ozempic-rybelsus-wegovy

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.