What is Glaucoma?

Glaucoma is an eye condition that damages the optic nerve, which carries visual information from your eye to your brain. Once this nerve is damaged, the vision loss is permanent and cannot be reversed.

It is often called the “silent thief of sight” because most people don’t notice symptoms in the early stages.

In Singapore, glaucoma is one of the leading causes of irreversible blindness. Around 3% of people over 50 are affected, and this rises to nearly 1 in 10 adults over 70. Despite this, many people are unaware they have the condition until vision is already affected.

Why Glaucoma Happens

Your eyes naturally produce fluid for eyes to see well . This fluid normally drains out through a delicate drainage system. When that system doesn’t work properly, pressure builds up.

Over time, this pressure can damage the optic nerve.

But here’s what many people don’t realise: glaucoma doesn’t always involve high pressure.

Some people develop optic nerve damage even when their eye pressure is within a normal range. This is when the optic nerve is more vulnerable to damage even at lower eye pressures. This is known as normal-tension glaucoma, and it’s one reason why regular eye exams are so important.

Signs & Symptoms 

Early Signs of Glaucoma

One of the biggest challenges with glaucoma is that early stages usually have no symptoms.

For the most common type (open-angle glaucoma), vision loss happens slowly and often starts with peripheral (side) vision. Because central vision remains clear at first, many people don’t realise anything is wrong.

By the time symptoms become noticeable, the condition is often already advanced, and irreversible.

Common Symptoms to Watch For

As glaucoma progresses, you may begin to notice:

• Gradual loss of side vision
• Blurred or dim vision
• Difficulty seeing at night
• Tunnel vision in later stages

In contrast, acute angle-closure glaucoma can cause sudden and severe symptoms:

• Intense eye pain
• Red eye
• Halos around lights
• Nausea or vomiting
• Sudden blurred vision

This is a medical emergency and requires immediate treatment.

Types of Glaucoma

Glaucoma isn’t just one condition, it’s a group of eye diseases that can affect vision in different ways. It includes several types, each affecting the eye differently.

1. Open Angle-Glaucoma

Where fluid pressure builds up in the eye, even when the fluid drainage pathways are open, as they are not functioning properly. Symptoms often appear gradually and may include:

• Loss of peripheral (side) vision
• Blurred vision
• Difficulty seeing in low light
• Tunnel vision later stages

2. Angle - Closure Glaucoma

Acute angle-closure glaucoma occurs when the drainage angle of the eye suddenly becomes blocked. This causes a rapid rise in eye pressure. Symptoms often appear gradually and may include:

• Severe eye pain
• Blurred or hazy vision
• Halos around light
• Red eye
• Nausea and vomiting

It is more common in older adults, females and Asian.

Chronic angle closure glaucoma may be more gradual, with the drainage angle progressively narrowing. Symptoms may be similar to open angle glaucoma.

3. Normal-Tension Glaucoma

Optic nerve damage occurs despite normal eye pressure. Blood flow issues to the optic nerve, or optic nerve vulnerability may play a role.

4. Secondary Glaucoma

This occurs when another condition such as cataracts, diabetes, eye inflammation (uveitis), or certain medications, increases pressure inside the eye.

5. Pigmentary Glaucoma

Caused by pigment particles blocking the eye’s drainage system, leading to increased pressure.

Who Is at Higher Risk?

You may be more likely to develop glaucoma if you:

• Are over 40 years old
• Have a family history of glaucoma
• Have diabetes or high blood pressure
• Are highly short-sighted (myopia) or long-sighted (hyperopia)
• Use steroid medications long-term
• Have obstructive sleep apnoea
• Have had previous eye injuries

Glaucoma often affects both eyes, but one eye may worsen faster than the other.

How is Glaucoma Diagnosed?

Glaucoma is usually detected through a comprehensive eye examination, often before symptoms appear. The doctor checks your eye pressure, examines the optic nerve, looks at the eye drainage system, and tests your field of vision

Common tests include:

• Eye pressure measurement (tonometry)
• Optic nerve assessment
• Visual field test (checks side vision)
• Corneal thickness measurement
• OCT imaging (detailed nerve scan)

These exams usually take about 20 to 45 minutes and can detect glaucoma early, often before symptoms appear. Regular eye examinations are recommended, especially from around age 40.

Treatment Options for Glaucoma

While glaucoma damage cannot be reversed, the good news is that it can be effectively controlled, especially when detected early, to prevent further worsening of vision.

1. Eye Drops (First-Line Treatment)

Medicated eye drops help reduce eye pressure and are the most common treatment.

2. Laser Treatment

Laser procedures can improve fluid drainage and help lower eye pressure.

3. Surgery and other therapies

Surgery may be recommended if other treatments are not effective. It works by creating new drainage pathways or reducing fluid production. Early glaucoma may now be treated by minimally invasive glaucoma surgeries.

Prevention

Glaucoma may not always be prevented, but regular eye examinations can help detect it early and prevent further serious vision loss. Maintaining a healthy lifestyle, managing conditions like diabetes or high blood pressure, and protecting your eyes from injury may also help reduce the risk.

When to see a Doctor

You should see a doctor if you notice symptoms such as:

• Blurred vision
• Loss of side vision
• Eye pain
• Headaches
• Halos around lights

It is also important to have regular eye examinations, especially if you are over 40, have a family history of glaucoma, or have conditions like diabetes or high blood pressure. Early checkups can help detect glaucoma before serious vision loss occurs.