Glaucoma: at what age to get screened and which signs to watch for

Glaucoma screening starts at age 40 with a comprehensive eye exam, because this disease of the optic nerve usually causes no symptoms before it has destroyed part of the visual field. In France, about one million people live with chronic glaucoma and 400,000 of them are unaware of it, according to Santé.fr, the French public health portal. The risk rises with age, family history, nearsightedness (myopia) and diabetes. Treatment started early halves the risk of the disease getting worse: the eye exam at 40 remains the most useful preventive step for your vision.

Glaucoma: definition and main forms

Glaucoma is a group of diseases that slowly destroy the fibers of the optic nerve, the cable that connects the retina to the brain. This nerve contains about 1.5 million fibers, and each fiber lost is lost for good: the National Eye Institute notes that treatment cannot undo damage already done to vision. The loss begins at the edges of the visual field, while central vision, the kind you use for reading, stays intact for a long time.

The disease is the second leading cause of blindness in developed countries, after age-related macular degeneration. The World Health Organization attributes 7.7 million cases of visual impairment or blindness worldwide to this disease. A meta-analysis of 50 population studies puts its prevalence at 3.54% between ages 40 and 80, or 76 million people in 2020 and a projected 111.8 million in 2040 (Tham et al., 2014).

In practice, three forms stand out. They differ both in pace and in degree of urgency.

Mechanism: why the optic nerve wears down with age

Glaucoma arises from an imbalance between the pressure inside the eye and the resilience of the optic nerve. The eye continuously produces a fluid, the aqueous humor, which drains through a filter located in the angle between the iris and the cornea. If this drainage slows down, pressure rises. It should stay below 20 mmHg, the average being 15 mmHg, according to Inserm, France’s national health research institute. Pressure that is too high for a given nerve compresses its fibers at the point where they leave the eye, the optic disc.

Pressure does not explain everything, though. Several mechanisms add up:

• Drainage of the aqueous humor that slows over the years, which raises the pressure.
• An insufficient blood supply to the optic nerve, suspected in people with migraine or severe myopia.
• An energy weakness of the retinal ganglion cells, whose fibers make up the optic nerve.
• A genetic predisposition: about 30% of glaucoma cases are hereditary, according to Inserm.
• A particular anatomy, such as a narrow drainage angle in farsighted people or a thin cornea.

The energy hypothesis ties the disease directly to aging. Ganglion cells burn a great deal of energy and depend on their mitochondria. In mice prone to the disease, mitochondrial abnormalities appear before any cell loss, and retinal levels of NAD+, a key molecule in energy production, fall with age. Giving nicotinamide (a form of vitamin B3 and a precursor of NAD+) by mouth protected the eyes: at the highest dose, 93% of eyes remained unaffected (Williams et al., 2017). This animal result places the disease among those linked to mitochondrial dysfunction, one of the biological hallmarks of aging. The role of NAD+ in aging is covered in our article on NAD+ precursors.

What the science says: who is at risk and why treating early matters

Family history, age, African ancestry, myopia and diabetes are the best-quantified risk factors for glaucoma, and early treatment clearly slows the disease. Diagnosis remains the first hurdle: a meta-analysis of 55 population studies (189,359 participants) shows that more than half of cases were unknown before the study exam, in every region of the world (Soh et al., 2021).

Heredity weighs heavily. In the Rotterdam Study, 10.4% of the brothers and sisters of patients were affected, compared with 0.7% in control families. Their lifetime risk reached 22.0% versus 2.3%, a ratio of 9.2 (Wolfs et al., 1998). In Baltimore, among 5,308 adults examined, the disease was 4 to 5 times more common in African Americans: 11.26% after age 80, versus 2.16% in Americans of European descent (Tielsch et al., 1991).

Myopia and diabetes also count. A meta-analysis of 13 studies (48,161 people) links myopia to a risk multiplied by 1.88 (Marcus et al., 2011). Another, covering 47 studies and nearly 3 million people, puts the excess risk linked to diabetes at 48% (Zhao et al., 2015). These studies are observational: they describe associations, not causes.

Treatment trials, on the other hand, are randomized. In the EMGT trial, 255 patients aged 50 to 80 with early glaucoma were followed for 6 years. Lowering eye pressure by 25% (5.1 mmHg) brought progression down to 45% of patients, compared with 62% without treatment (Heijl et al., 2002). The risk of progression was halved, and each millimeter of mercury gained reduced it by about 10% (Leske et al., 2003).

In 1,636 people with high pressure but a still healthy nerve, eye drops lowered the 5-year risk of developing the disease from 9.5% to 4.4% (Kass et al., 2002). The British UKGTS trial (516 patients) compared latanoprost eye drops with a placebo: the visual field was preserved longer under treatment, with a 56% lower risk of deterioration at 24 months (Garway-Heath et al., 2015). Laser is an alternative: after selective laser treatment of the drainage filter, 74.2% of the 356 patients treated needed no eye drops 3 years later (Gazzard et al., 2019).

Nicotinamide is being tested in humans, but the data remain preliminary. In 57 patients already on treatment, 1.5 then 3 g per day for 12 weeks improved an electrical index of retinal function by 14.8%, versus 5.2% with placebo (Hui et al., 2020). Combined with pyruvate, it increased the number of improved visual field points (15 versus 7) over about 2 months, in 32 patients (De Moraes et al., 2022). None of these trials shows a lasting slowdown of the disease. These doses far exceed dietary intake and should be discussed only with an ophthalmologist, as a complement to the prescribed treatment.

In practice: at what age should you get screened for glaucoma?

The first glaucoma screening takes place at age 40, even without any vision problem. Inserm, France’s national health research institute, recommends systematic, regular screening from that age, stepped up in affected families. For the frequency of checkups, the American Academy of Ophthalmology sets intervals by age for adults with no symptoms and no risk factors (Wallace et al., 2026).

These intervals get shorter when a risk factor is present: an affected close relative, severe myopia, diabetes, African ancestry, long-term corticosteroid treatment or eye pressure already measured as high. The ophthalmologist then sets the schedule. The same examination of the back of the eye helps detect age-related macular degeneration, the other major cause of vision loss after 50.

Screening is about more than measuring eye pressure. About one in three cases of chronic glaucoma occurs with normal pressure, and the US National Library of Medicine’s MedlinePlus service points out that the pressure an optic nerve can tolerate differs from one person to another. A comprehensive exam combines several measurements:

One nuance is worth knowing. In the United States, the Preventive Services Task Force judges the evidence insufficient to recommend glaucoma screening by primary care physicians for all adults over 40 (Mangione et al., 2022). This opinion concerns mass screening in primary care. It does not call into question the comprehensive exam by an ophthalmologist, nor the close follow-up of people at risk.

Glaucoma warning signs and tips to protect your vision

Chronic glaucoma can go without any symptoms for 10 to 20 years, according to the French public health portal: noticing nothing therefore proves nothing. Each eye often makes up for the missing areas of the other, which delays awareness even further. The signs below appear late, or point to an emergency:

• You bump into doors or furniture, or miss a step, especially on one side.
• When driving, pedestrians or vehicles seem to appear out of nowhere at the sides.
• You struggle in dim light and contrasts look less sharp.
• Dull aches, a feeling of pressure in the eye, watery eyes or headaches keep coming back (rare signs).
• Colored halos appear around lights, with temporarily blurred vision.
• Emergency: a red, hard and very painful eye, a sudden drop in vision, sometimes nausea. Call emergency services (911 in the US, 999 in the UK, 112 in Europe) or go to an eye emergency department, because vision can be lost within a few hours.

The steps that protect the optic nerve rest first on screening, then on following the treatment when one is prescribed:

• Book a comprehensive eye exam at 40, without waiting for a problem.
• If you are diagnosed with glaucoma, tell your brothers, sisters and children: their risk is markedly higher.
• Tell the ophthalmologist about any long-term corticosteroid treatment, especially in eye drop form.
• Use your prescribed eye drops every day, at the times indicated, waiting 5 minutes between two different drops. Never stop them without medical advice.
• Move every day. In 141 patients fitted with an accelerometer, 5,000 more steps per day were associated with visual field loss about 10% slower (Lee et al., 2019). The link has not been shown to be causal, but regular walking also benefits the heart and the brain.
• Stop smoking and have your blood pressure and blood sugar monitored, as the French public health portal recommends to limit this risk.
• Wear protective glasses for ball sports and DIY projects: an eye injury increases the risk.
• If you have been told you have a narrow angle, mention it before any eye drops that dilate the pupil.

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Frequently asked questions about glaucoma

At what age should you get screened for glaucoma?

The first glaucoma screening is recommended at age 40, even without any vision problem, according to Inserm, France’s national health research institute. It should be stepped up in case of family history, severe myopia, diabetes, African ancestry or long-term corticosteroid use. Without risk factors, the American Academy of Ophthalmology advises an exam every 2 to 4 years between 40 and 54, then every 1 to 2 years after 65.

What are the first signs of glaucoma?

Most often, there are none: chronic glaucoma can remain symptom-free for 10 to 20 years. The first signs people notice come late: obstacles missed off to the side, missed steps, cars that seem to appear out of nowhere when driving, trouble seeing in dim light. The center of vision stays sharp for a long time, which delays the visit to a doctor. Only an eye exam detects the disease before these losses.

Can you have glaucoma with normal eye pressure?

Yes. In about a third of people with chronic glaucoma, intraocular pressure stays within the usual range, below 20 mmHg. This is called normal-tension glaucoma. Insufficient blood supply to the optic nerve may be involved, especially in people with migraine or severe myopia. That is why screening is never limited to measuring pressure: examining the optic nerve remains essential.

Is glaucoma hereditary?

Partly. Inserm, France’s national health research institute, estimates that about 30% of glaucoma cases are hereditary. In the Rotterdam Study, the siblings of patients had a lifetime risk of 22%, compared with 2.3% in control families, a risk multiplied by 9. If a close relative is affected, tell your family and ask the ophthalmologist at what age to start checkups.

What is the difference between acute and chronic glaucoma?

Chronic open-angle glaucoma accounts for 80 to 90% of cases: it progresses slowly and painlessly, over years. Acute glaucoma occurs when the eye’s drainage angle closes suddenly: very severe pain, a red and hard eye, colored halos, loss of vision, sometimes nausea. It is an emergency, because vision in the affected eye can be lost within a few hours. Call emergency services (911 in the US, 999 in the UK, 112 in Europe) or go to an eye emergency department.

Can vision lost to glaucoma come back?

No. Destroyed optic nerve fibers do not regenerate, and current treatments do not restore lost vision. They slow the worsening: in a trial of 255 patients, lowering eye pressure by 25% halved the risk of progression. An early diagnosis, while the visual field is still intact, therefore changes the outlook. Nicotinamide (vitamin B3) is under study, without long-term evidence.