By the time you notice something is wrong, the damage is already done
Each May, Brazil's Maio Verde campaign turns public attention toward a disease that steals sight without announcement — glaucoma, a progressive deterioration of the optic nerve that affects more than 1.7 million Brazilians, most of whom do not yet know they carry it. Because the condition advances in complete silence, the only meaningful defense is deliberate, early screening — a truth that medicine understands but that daily life too easily forgets. The campaign is, at its core, a reminder that some losses are preventable only if we look for them before they arrive.
- Glaucoma is already present in over 1.7 million Brazilians, and the majority remain undiagnosed precisely because the disease produces no pain, no warning, and no early symptoms to prompt concern.
- By the time a patient notices the edges of their vision dimming or narrowing, irreversible optic nerve damage has already occurred — the lost sight will not return, no matter the treatment that follows.
- Diagnosis requires a full ophthalmologic workup — intraocular pressure, optic nerve imaging, visual field testing, and OCT — because no single measurement is sufficient, and some forms of glaucoma develop even with normal pressure readings.
- Treatment exists and works — eye drops, laser therapy, and surgery can all halt progression — but only if patients are diagnosed early and commit to lifelong management of a disease they may never feel.
- Maio Verde is pressing Brazilians over 40, and especially those with known risk factors, to seek regular eye screening, framing the absence of symptoms not as safety, but as the very reason vigilance cannot wait.
Glaucoma advances without pain, without visible warning, and without mercy. By the time a patient perceives something wrong — a subtle narrowing at the edges of sight, a dimming that seems easy to dismiss — the optic nerve has already sustained damage that no treatment can reverse. This is the quiet catastrophe that Brazil's annual Maio Verde campaign confronts each May, directing public attention toward a disease that more than 1.7 million Brazilians carry, most of them unknowingly.
Dr. Mariana Barros, an ophthalmologist at Hospital de Olhos Santa Luzia, is direct about what this silence means: early-stage glaucoma presents no symptoms, which is precisely why waiting for something to feel wrong is not a strategy — it is a path toward irreversible blindness. Detection requires a comprehensive examination, including intraocular pressure measurement, optic nerve analysis, visual field testing, and OCT imaging. Crucially, not all glaucoma involves elevated pressure; normal-tension forms exist, making integrated assessment essential.
The disease takes more than one shape. Open-angle glaucoma erodes peripheral vision slowly over years, so gradually that daily life feels unchanged until the field has significantly contracted. Angle-closure glaucoma can strike suddenly and severely. In both cases, the damage accumulates without pause and cannot be undone.
Glaucoma has no cure, but early diagnosis opens the door to effective management. Medicated eye drops, laser therapy, and surgery can all reduce intraocular pressure and halt further nerve damage. The harder challenge is adherence — patients must maintain lifelong treatment for a condition they cannot feel, and stopping medication can accelerate the very progression they are trying to prevent.
Maio Verde exists to close the gap between what medicine knows and what the public acts on. By encouraging regular screening — particularly for anyone over 40 or carrying known risk factors — the campaign works to make preventable blindness genuinely preventable. The disease will not announce itself. The campaign is asking Brazilians to look anyway.
Glaucoma moves through the eye like a thief in daylight. You feel nothing. You see nothing wrong. And then one day, without warning, a piece of your vision is simply gone—and it does not come back.
This is the central tragedy that the Maio Verde campaign, Brazil's annual awareness push, confronts each May. Glaucoma ranks among the world's leading causes of irreversible blindness, and in Brazil alone, more than 1.7 million people live with the disease. Most of them do not know it yet. The condition is a progressive damage to the optic nerve, typically driven by elevated pressure inside the eye, and it unfolds almost entirely in silence. By the time a patient notices something amiss—a dimming at the edges of vision, a narrowing of the visual field—the harm is already done. The lost sight cannot be restored.
Dr. Mariana Barros, an ophthalmologist at Hospital de Olhos Santa Luzia, puts it plainly: glaucoma presents no symptoms in its early stages. When patients finally perceive a change, vision loss has already occurred. This is why early detection is not optional—it is the only real defense against blindness. The disease does not announce itself. It requires you to look for it.
Detecting glaucoma demands more than a single test. A complete eye examination includes measurement of intraocular pressure, direct analysis of the optic nerve, visual field testing, and optical coherence tomography (OCT) imaging to catch structural and functional changes before they become irreversible. One complication: not all glaucoma cases involve high eye pressure. Normal-tension glaucoma exists, which means a patient can have the disease even with seemingly safe pressure readings. This is why diagnosis requires an integrated assessment of multiple findings, not reliance on any one number.
The disease takes different forms. Open-angle glaucoma, the most common type, progresses slowly and silently over years. Angle-closure glaucoma can strike suddenly and severely. In both cases, the damage to the optic nerve is continuous and irreversible once it begins. In early stages, peripheral vision fades so subtly that daily life feels unchanged. As the disease advances, the visual field contracts further, eventually narrowing to what doctors call tunnel vision, and potentially to total blindness.
Dr. Barros emphasizes that many patients discover glaucoma only after substantial field loss has occurred—loss that cannot be recovered. This is why anyone over 40 should undergo regular eye screening, and why those with risk factors need rigorous, ongoing monitoring. The absence of symptoms is not reassurance. It is precisely the reason screening must be active and deliberate.
Glaucoma has no cure, but it does have effective management when caught early. Treatment aims to lower intraocular pressure to safe levels, halting further damage to the optic nerve. Options range from medicated eye drops to laser therapy to surgical intervention, depending on severity and how the patient responds. The challenge is adherence. Glaucoma is chronic and often asymptomatic, which means patients must commit to lifelong medication use without feeling immediate benefit. Stopping treatment can accelerate the disease's progression.
Campaigns like Maio Verde serve a critical function: they widen access to information and encourage sustained attention to eye health. By reinforcing the necessity of early diagnosis and regular follow-up, they directly reduce cases of preventable blindness and preserve quality of life across the population. The disease is silent, but the call to action need not be.
Citas Notables
Glaucoma is a disease that in most cases presents no symptoms at the start. When the patient notices a change, vision loss has often already happened. This is why early diagnosis is essential to preserve sight.— Dr. Mariana Barros, ophthalmologist at Hospital de Olhos Santa Luzia
Glaucoma can evolve silently for years. Many patients only realize they have it when field loss is already present, and that loss cannot be recovered.— Dr. Mariana Barros
La Conversación del Hearth Otra perspectiva de la historia
Why does glaucoma catch so many people off guard? What makes it different from other eye diseases?
It gives no warning. You could have it for years, losing vision in small increments at the edges, and feel nothing at all. By the time your brain registers something is wrong, the damage is already permanent. Most diseases announce themselves. Glaucoma just takes.
So screening is really the only defense?
It's the only defense we have right now. There's no cure. But if you catch it early—before the nerve damage becomes severe—you can slow it down, maybe stop it entirely. That's why a person over 40 needs to be checked regularly, not just when something feels off.
What happens to someone who gets diagnosed late?
They live with restricted vision. The world narrows. Some lose their independence, their ability to work, their sense of autonomy. And they know it could have been prevented if they'd had one eye exam years earlier.
Is treatment difficult?
Not technically. Eye drops, laser, surgery—these work. The hard part is that you have to take medication every day for the rest of your life for a disease you can't feel. Many people stop. Then the pressure builds again, and the nerve keeps dying.
What does the campaign actually change?
It gets people into the chair. It makes a 45-year-old think, "Maybe I should get my eyes checked." It tells families that this is real, that it's common, that it's preventable. Information is the only tool we have before diagnosis happens.