Patient Information

Understanding Glaucoma

Glaucoma is one of the leading causes of irreversible vision loss worldwide. However, with early detection and appropriate treatment, it is possible to control the disease and preserve vision in most cases. This guide explains what glaucoma is, how it is detected, and what you can do about it.

This information is for educational purposes. It does not replace a clinical assessment by your ophthalmologist.

What is glaucoma

Glaucoma is a group of eye diseases that damage the optic nerve, the structure responsible for transmitting visual information from the eye to the brain. When the optic nerve is damaged, the visual field gradually narrows, usually starting with peripheral (side) vision.

In most cases, this damage is related to elevated intraocular pressure, although glaucoma can also develop with normal pressure levels. This is why a complete evaluation is essential for an accurate diagnosis.

The role of the optic nerve

The optic nerve is formed by over a million nerve fibers that carry visual signals to the brain. In glaucoma, these fibers are progressively lost. Once they are damaged, they cannot be regenerated.

This is why early detection is so important: the goal of treatment is to prevent further loss, not to recover vision that has already been lost.

Understanding glaucoma

How glaucoma damages the optic nerve

Healthy fiberDestroyed fiber

A healthy optic nerve

The optic nerve is made up of around one million fibers. Each carries a small part of what you see from the eye to the brain.

When all of them work, the complete image reaches the brain.

Treatment does not repair what has been lost. Its aim is to protect the remaining fibers.

Why does it progress without symptoms?

The brain is remarkably good at compensating for early visual field loss. Because glaucoma typically affects peripheral vision first, most patients do not notice any change until the disease is advanced.

This is why glaucoma is often called the "silent thief of sight." Regular eye examinations are the only reliable way to detect it early.

How glaucoma affects the visual field

Normal visionFull visual field. No symptoms.
Early glaucomaPeripheral loss. The patient does not notice.
Advanced glaucomaTunnel vision. Affects daily life.

Intraocular pressure and glaucoma

Intraocular pressure (IOP) is one of the main risk factors for glaucoma and the only one that can currently be modified with treatment. However, having high IOP does not automatically mean you have glaucoma, and some patients develop glaucoma with statistically normal pressures.

This is why diagnosis cannot rely on pressure measurement alone. A comprehensive evaluation of the optic nerve and visual function is necessary.

How is glaucoma diagnosed?

Three pillars that support one another

No single test diagnoses glaucoma on its own. The diagnosis comes from combining three types of information: the pressure the nerve is under, its structure, and the vision it produces.

Glaucoma diagnosis

A comprehensive assessment, not an isolated number

  1. Pressure

    How much pressure is the nerve under?

    • TonometryMeasures intraocular pressure. It matters, but on its own it is not enough to make a diagnosis.
    • Adjusts the readingPachymetryMeasures corneal thickness, a factor that influences the accuracy of the pressure reading.

  2. Structure

    Is there damage to the optic nerve fibers?

    • Optic nerve examinationDirect assessment of the optic disc through the microscope or using fundus photographs.
    • Optical coherence tomography (OCT)A scan that measures the thickness of the nerve fiber layer. It detects damage before any symptoms appear.

  3. Function

    How much vision has already been lost?

    • Visual field test (perimetry)A map of visual field sensitivity. It identifies areas of loss, including those the patient is not yet aware of.

These tests are repeated periodically. In glaucoma what matters is not only the result on a given day, but how it changes over time: management is a long-term process.

Available treatments

One goal, different steps

Glaucoma has no cure, but it can be controlled. Every option pursues the same aim, and they are added to or replace one another depending on what each eye needs.

The goal is always the same: lowering intraocular pressure to protect the nerve. What changes from one step to the next is how that is achieved.

  1. 01

    Eye drops

    WhenThe starting point for most patients.

    The most common initial treatment. Its effectiveness depends entirely on consistency: using them every day, at the prescribed time, is what keeps the disease from progressing.

  2. 02

    Laser (SLT)

    WhenIf drops do not lower the pressure enough or are not well tolerated. In selected cases it may be considered from the outset.

    A procedure performed in the clinic that helps fluid drain out of the eye. It can reduce or delay the need for eye drops.

  3. 03

    Surgery

    WhenIf a greater or more stable pressure reduction is needed, or the disease keeps progressing.

    This includes minimally invasive techniques (MIGS) and filtering surgery, which create a new drainage pathway for the fluid inside the eye.

    See the surgery guide

This order is the usual one, not a fixed rule. After reviewing your case — pressure, the state of the nerve and how fast it is progressing — we will choose the approach that best protects your vision in the long term.

What can you do

  • ✓Attend all scheduled follow-up appointments, even if you feel fine
  • ✓Use your prescribed eye drops every day, at the recommended times
  • ✓Report any side effects from your medication so the treatment can be adjusted
  • ✓If you have a family history of glaucoma, inform your ophthalmologist
  • ✓Do not stop or modify your treatment without consulting your doctor

Glaucoma management is a long-term commitment. Consistency with treatment and follow-up is the most important factor in preserving your vision.

When to seek urgent care

Although most forms of glaucoma progress slowly, some situations require immediate attention:

  • Sudden, severe eye pain accompanied by nausea or vomiting
  • Abrupt loss of vision in one or both eyes
  • Seeing colored halos around lights, especially with eye pain
  • Intense redness of the eye with blurred vision

These symptoms may indicate an acute angle-closure crisis, which is a medical emergency. Seek immediate attention at the nearest emergency department.

Frequently asked questions

Currently, glaucoma cannot be cured. However, with appropriate treatment, its progression can be effectively controlled in most patients. The key is early diagnosis and consistent follow-up.

Yes. A significant percentage of patients develop glaucoma with statistically normal pressures. This is why a complete evaluation — including OCT, visual field testing, and optic nerve examination — is necessary for accurate diagnosis.

With timely diagnosis and proper treatment, most patients with glaucoma retain useful vision throughout their lives. The risk of severe vision loss is significantly higher in patients who are diagnosed late or do not follow their treatment.

The frequency depends on the stage of the disease and individual risk factors. Patients with diagnosed glaucoma typically need follow-up every 3 to 6 months. Those at risk should have at least an annual comprehensive exam.

Having a first-degree relative with glaucoma increases your risk. If you have a family history, inform your ophthalmologist so that appropriate screening can be scheduled.

Want to check your eye health?

If you have risk factors for glaucoma or have not had an eye exam recently, consider scheduling an evaluation.

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