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Optic Nerve Health

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Home Risk Factors Blood pressure

Blood pressure

Monitoring, management, and the proposed link to NAION

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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High blood pressure is associated with NAION: large reviews found roughly 1.3 to 1.5 times the odds.¹ ² Researchers have also proposed that blood pressure that falls too low at night may reduce blood flow to the optic nerve in people who are already at risk.³ Both high and very low pressure can matter, which is why steady, well-matched treatment is the goal.

For patients and families

How blood pressure is measured

  • In the office. A single reading can be affected by stress, talking, or rushing. Blood pressure categories for adults are: normal, below 120/80; elevated, 120–129 systolic with diastolic below 80; stage 1 high blood pressure, 130–139 systolic or 80–89 diastolic; stage 2, 140/90 or higher.⁴
  • At home. A validated upper-arm cuff gives readings in your normal life. Current U.S. guidelines recommend home (or 24-hour) monitoring to confirm high blood pressure, and home monitoring to guide treatment changes for people already taking medicine.⁴ Sit with your back supported, feet flat, and arm resting at heart level; take two readings, morning and evening, and bring the log or device to your visits.
  • 24-hour ambulatory monitoring (ABPM). You wear a cuff connected to a small recorder for a day and a night. It takes readings automatically, about every 15–30 minutes during the day and every 30–60 minutes at night,⁴ so it is the standard way to see what your blood pressure does while you sleep.⁵

What “dipping” means

Blood pressure normally falls during sleep. On a 24-hour monitor, doctors describe the nighttime fall as a percentage of the daytime average:⁵

  • Dipper (typical): falls about 10–20% at night.
  • Non-dipper: falls less than 10%. This is more common in people with sleep apnea, kidney disease, diabetes, and some nerve conditions.⁵
  • Extreme (over-) dipper: falls more than 20%.
Illustrative line chart of systolic blood pressure from 8 am to 8 am with the sleep period shaded. Three curves: a non-dipper that falls less than 10 percent at night, a typical dipper that falls about 10 to 20 percent, and an extreme dipper that falls more than 20 percent. Labeled illustrative, not patient data.
Illustrative, not patient data. Dipping categories are conventional percentage definitions used with 24-hour monitoring.

How high blood pressure is managed

  • Lifestyle: losing excess weight (in trials, about 1 mm Hg lower blood pressure for each kilogram lost),⁶ less salt, regular activity, limiting alcohol, and treating sleep apnea.⁴ ⁵
  • Medicines: chosen and adjusted by your clinician. Take them as prescribed.
  • Regular follow-up: your needs can change, for example when you lose weight, start a new medicine, or become dehydrated.

The proposed link to NAION

NAION is often noticed on waking. In a 1994 study that used 24-hour monitors in people with optic nerve conditions, researchers found that low blood pressure at night was associated with worsening vision in some people with NAION, especially those taking blood pressure medicines. They proposed that nighttime low pressure may be “the final insult” when other risk factors, such as a crowded optic disc, are present.³ This is a proposed mechanism. It has not been proven to cause NAION, and it has not been tested in randomized trials.

Should I change when I take my medicine?

Not on your own. A large trial of more than 21,000 people found that taking blood pressure medicine at night instead of in the morning made no difference to heart attacks, strokes, or vascular deaths.⁷ Whether timing matters for the optic nerve has not been studied in trials. If you have a crowded optic disc or have had NAION, ask the clinician who prescribes your blood pressure medicine whether a 24-hour monitor and a review of your doses and timing make sense. Tell your doctor if you feel dizzy or lightheaded, especially at night or when standing up.

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.

Keep your usual doctor in the loop

If an eye doctor or a GLP-1 prescriber is not the clinician who manages your blood pressure, keep your regular visits with the one who does, and let them know about weight loss or new medicines. Never stop or change a blood pressure medicine without talking to the doctor who prescribes it.

For clinicians

Measurement

  • The 2025 AHA/ACC guideline recommends out-of-office BP (HBPM or ABPM) to confirm a diagnosis of hypertension, and HBPM with co-interventions for monitoring and titration in treated adults.⁴
  • ABPM is the reference method for nocturnal BP; nocturnal phenotypes include nocturnal hypertension, non-dipping, and extreme dipping. Validated home devices with nocturnal function are an alternative; cuffless wearables still need validation.⁵
  • Dipping ratio = (daytime mean − nighttime mean) / daytime mean. Conventional categories: <10% non-dipper, 10–20% dipper, >20% extreme dipper; a nighttime rise is “reverse dipping.”⁵

NAION relevance

  • Association: hypertension pooled OR 1.50 (95% CI 1.16–1.94) in a 2022 cardiometabolic meta-analysis;² RR 1.28 (1.20–1.37) in a 49-study meta-analysis.¹
  • Proposed mechanism: Hayreh and colleagues (166 patients with ABPM) reported an association between nocturnal hypotension and progressive field loss, particularly in AION patients taking oral antihypertensive (hypotensive) therapy, and proposed nocturnal hypotension as a final insult in a multifactorial setting.³ Evidence is observational; no randomized data test whether avoiding nocturnal hypotension reduces NAION.
  • Bedtime dosing: TIME (n = 21,104; median 5.2 years) found no difference in major cardiovascular outcomes between evening and morning dosing (HR 0.95, 95% CI 0.83–1.10).⁷ The ESH notes chronotherapy has shown inconsistent results.⁵ The concern about bedtime dosing in patients at risk of NAION therefore rests on the proposed nocturnal-hypotension mechanism, not on outcome data.

Practical approach (individualized)

  • In patients with a crowded disc (“disc at risk”), prior NAION in one eye, or new symptoms of orthostasis, consider ABPM to look for extreme dipping or nocturnal hypotension, and review agent, dose, and timing with the treating clinician.
  • During GLP-1–associated weight loss, BP often falls; review antihypertensive needs as weight drops.
  • Treat comorbid OSA, which is associated with non-dipping and nocturnal hypertension.⁵ See Sleep apnea.

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.

Coordination

Eye care clinicians should communicate findings (disc at risk, prior NAION) to the PCP or cardiologist rather than adjusting antihypertensives themselves. Patients should never stop or change BP medicines without their prescribing clinician. Letter templates are on Patient and PCP letter templates.

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. Hayreh SS, et al. Nocturnal arterial hypotension and its role in optic nerve head and ocular ischemic disorders. Am J Ophthalmol. 1994;117(5):603-624. https://pubmed.ncbi.nlm.nih.gov/8172267/
  4. Jones DW, et al. 2025 AHA/ACC/AANP/AAPA/ABC/ACCP/ACPM/AGS/AMA/ASPC/NMA/PCNA/SGIM Guideline for the Prevention, Detection, Evaluation, and Management of High Blood Pressure in Adults. J Am Coll Cardiol. 2025;86(18):1567-1678. https://pubmed.ncbi.nlm.nih.gov/40815242/
  5. Parati G, et al. Nocturnal blood pressure: pathophysiology, measurement and clinical implications. Position paper of the European Society of Hypertension. J Hypertens. 2025;43(8):1296-1318. https://pubmed.ncbi.nlm.nih.gov/40509714/
  6. 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/
  7. Mackenzie IS, et al. Cardiovascular outcomes in adults with hypertension with evening versus morning dosing of usual antihypertensives in the UK (TIME study). Lancet. 2022;400(10361):1417-1425. https://pubmed.ncbi.nlm.nih.gov/36240838/

The chart on this page is an original illustration, not patient data.

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.