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Glaucoma Explained: A Complete Guide to Symptoms, Diagnosis & Treatment

Glaucoma Explained: Early Signs, Risk Factors, Diagnosis & Treatment

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Last updated: July 2026

Reviewed by the First Choice Vision Optometry Team

This article has been reviewed by the experienced optometry team at First Choice Vision to ensure it reflects current evidence-based recommendations and current best practices in glaucoma detection, diagnosis and management.

Table of Contents

  • What Is Glaucoma?
  • Why Is Glaucoma Called the Silent Thief of Sight?
  • Types of Glaucoma
  • Early Signs and Symptoms
  • Who Is at Risk?
  • How Is Glaucoma Diagnosed?
  • What Tests Does an Optometrist Perform?
  • Treatment Options
  • Can Glaucoma Be Prevented?
  • Frequently Asked Questions
  • When Should You Have Your Eyes Checked?

Key Takeaways

  • Glaucoma is one of the leading causes of irreversible vision loss worldwide.
  • Most people with early glaucoma have no noticeable symptoms.
  • Regular comprehensive eye examinations are the best way to detect glaucoma before vision is permanently affected.
  • High eye pressure is an important risk factor, but glaucoma can also occur with normal eye pressure.
  • Early diagnosis and treatment can help slow or prevent further vision loss.

What Is Glaucoma?

Glaucoma is a group of eye diseases that damage the optic nerve, the vital structure responsible for carrying visual information from your eye to your brain.

The optic nerve contains more than one million nerve fibres that work together to transmit everything you see. When these delicate fibres become damaged, parts of your vision can gradually be lost.

Unlike many other eye conditions, the vision already lost from glaucoma cannot usually be restored. This is why early detection is so important.

Although glaucoma is often associated with increased eye pressure, not everyone with high eye pressure develops glaucoma, and some people develop glaucoma despite having eye pressure within the normal range.

For this reason, diagnosing glaucoma involves much more than simply measuring eye pressure. A comprehensive eye examination allows your optometrist to assess the health of your optic nerve and identify early signs of damage before you notice any changes in your vision.

A healthy tear film is essential for keeping your eyes comfortable, maintaining clear vision and protecting the front surface of the eye. When this delicate balance is disrupted, everyday activities such as reading, driving, working on a computer or wearing contact lenses can become uncomfortable.

Dry eye disease can range from occasional mild irritation to persistent symptoms that affect quality of life. Fortunately, with the right diagnosis and personalised treatment, most people can achieve significant relief and better long-term eye comfort.

Why Is Glaucoma Called the "Silent Thief of Sight"?

Glaucoma is often referred to as the silent thief of sight because it usually develops slowly and without obvious symptoms.

In the early stages, most people continue to see well and are completely unaware that damage is occurring.

Instead of affecting central vision first, glaucoma typically begins by reducing peripheral (side) vision. Because these changes happen gradually, the brain often adapts, making it difficult to notice the loss until significant damage has already occurred.

By the time symptoms become noticeable, permanent vision loss may already have occurred.

This is why many people are diagnosed during a routine comprehensive eye examination rather than because they noticed a problem themselves.

Why Early Detection Matters

One of the most encouraging aspects of glaucoma care is that early detection can make a significant difference.

Although glaucoma cannot currently be cured, modern treatments can often slow or stop further damage when the condition is detected early.

Regular eye examinations allow optometrists to identify subtle changes in the optic nerve long before vision is noticeably affected.

Early diagnosis means treatment can begin sooner, helping preserve the vision you have for many years to come.

Is Glaucoma Common?

Yes.

Glaucoma is one of the most common causes of irreversible blindness worldwide and affects millions of people.

The risk increases with age, particularly after the age of 40, although glaucoma can develop at almost any age.

Many people are surprised to learn they have glaucoma because they have no pain, no blurred vision and no obvious warning signs.

This is why regular comprehensive eye examinations remain one of the most important ways to protect your long-term eye health.

Can an Optometrist Detect Glaucoma?

Absolutely.

A comprehensive eye examination involves much more than checking whether you need glasses.

During your appointment, your optometrist may assess:

  • Eye pressure (intraocular pressure)
  • The health of your optic nerve
  • Your peripheral vision
  • The front and back of your eyes
  • Other risk factors for glaucoma

If your optometrist identifies findings that suggest glaucoma or an increased risk of developing glaucoma, they may recommend additional testing, ongoing monitoring or referral to an ophthalmologist for further assessment.

Did You Know?

Many people with early glaucoma have perfectly normal vision and experience no symptoms at all.

This is why glaucoma is often discovered during a routine eye examination rather than because someone notices a change in their eyesight.

Regular comprehensive eye examinations play an important role in detecting glaucoma and many other eye conditions before symptoms develop. If you’d like to learn more about what happens during an eye examination, stay tuned for our upcoming guide on Comprehensive Eye Examinations, or explore our current article on Dry Eye Disease: Symptoms, Causes, Treatments & When to See an Optometrist to learn how eye examinations help diagnose a range of eye conditions.

Types of Glaucoma

Although glaucoma is often discussed as a single condition, it actually refers to a group of eye diseases that damage the optic nerve.

The different types of glaucoma have different causes, rates of progression and treatment approaches.

Understanding these differences helps explain why regular comprehensive eye examinations are so important.

Primary Open-Angle Glaucoma

The Most Common Type of Glaucoma

Primary Open-Angle Glaucoma (POAG) is the most common form of glaucoma.

It develops gradually over many years and usually causes no pain and no noticeable symptoms during its early stages.

Inside the eye, a clear fluid called aqueous humour is continuously produced and drained to maintain healthy eye pressure.

In open-angle glaucoma, the drainage system remains physically open but becomes less efficient over time. As fluid drains more slowly, pressure inside the eye may increase, placing stress on the optic nerve.

However, it is important to remember that not everyone with open-angle glaucoma has high eye pressure. Some people develop optic nerve damage even when their eye pressure remains within the normal range.

Because vision changes occur slowly, many people are unaware they have glaucoma until it is detected during a routine eye examination.

Angle-Closure Glaucoma

Angle-Closure Glaucoma is much less common than open-angle glaucoma, but it can develop much more rapidly and may require urgent medical attention.

This type of glaucoma occurs when the drainage angle inside the eye becomes partially or completely blocked, preventing fluid from leaving the eye normally.

As a result, eye pressure can rise quickly.

Unlike open-angle glaucoma, angle-closure glaucoma may cause sudden symptoms such as:

  • Severe eye pain
  • Blurred vision
  • Headache
  • Halos around lights
  • Nausea or vomiting
  • Red eyes

A sudden attack of angle-closure glaucoma is considered a medical emergency.

Anyone experiencing these symptoms should seek immediate medical attention.

Normal-Tension Glaucoma

Many people believe glaucoma only occurs when eye pressure is high.

This is a common misconception.

Some people develop Normal-Tension Glaucoma, where optic nerve damage occurs even though eye pressure remains within the normal range.

Researchers continue to study why this happens, but factors such as reduced blood flow to the optic nerve and individual susceptibility may play a role.

This is one reason why measuring eye pressure alone is not enough to diagnose glaucoma.

A comprehensive eye examination includes assessment of the optic nerve, visual function and other important clinical findings.

Feature Open-Angle Glaucoma Angle-Closure Glaucoma
How common is it? Most common type Less common
Symptoms Usually none in the early stages Often sudden and severe
Onset Gradual Can occur suddenly
Pain Usually painless Often painful
Medical urgency Requires ongoing monitoring and treatment May require urgent medical attention

Ocular Hypertension

Another condition that often causes confusion is ocular hypertension.

Ocular hypertension means the pressure inside the eye is higher than average, but there is no evidence of glaucoma damage.

Having ocular hypertension does not necessarily mean you have glaucoma, but it does increase your risk of developing glaucoma in the future.

Your optometrist may recommend regular monitoring to ensure that the optic nerve remains healthy over time.

Early Signs and Symptoms of Glaucoma

One of the greatest challenges with glaucoma is that there are often no symptoms during the early stages.

This is why many people are diagnosed during a routine eye examination rather than because they noticed changes in their vision.

As glaucoma progresses, symptoms may include:

  • Gradual loss of peripheral (side) vision
  • Difficulty seeing objects beside you
  • Trouble seeing in dim lighting
  • Tunnel vision in advanced stages

Acute angle-closure glaucoma may develop very differently and can cause:

  • Sudden severe eye pain
  • Blurred vision
  • Halos around lights
  • Headache
  • Nausea
  • Vomiting

Because these symptoms can indicate a medical emergency, immediate assessment is essential.

Who Is Most at Risk of Glaucoma?

Anyone can develop glaucoma, but certain factors increase the likelihood.

Risk factors include:

  • Being over 40 years of age
  • Having a family history of glaucoma
  • Elevated eye pressure
  • Diabetes
  • High levels of short-sightedness (myopia)
  • Previous eye injury
  • Long-term steroid medication use
  • Certain ethnic backgrounds
  • Thin corneas

Having one or more risk factors does not mean you will definitely develop glaucoma, but it does mean regular comprehensive eye examinations become even more important.

Glaucoma Myths vs Facts

Myth

“If I can see clearly, I don’t have glaucoma.”

Fact

Most people with early glaucoma have no noticeable vision changes.


Myth

“High eye pressure always means glaucoma.”

Fact

High eye pressure is a risk factor, but many people with elevated eye pressure never develop glaucoma, while others develop glaucoma despite having normal eye pressure.


Myth

“Glaucoma only affects older people.”

Fact

The risk increases with age, but glaucoma can occur in younger adults and, more rarely, even in children.


Myth

“If no one in my family has glaucoma, I won’t get it.”

Fact

A family history increases your risk, but many people diagnosed with glaucoma have no known family history.

Did You Know?

It is estimated that around half of people with glaucoma don’t know they have it because the disease often develops without noticeable symptoms in its early stages.

This is why regular comprehensive eye examinations are considered one of the most effective ways to detect glaucoma before permanent vision loss occurs.

High levels of short-sightedness are one of several recognised risk factors for glaucoma. If you’d like to learn more about myopia and why managing its progression is important, read our guide Myopia Control in Children: Which Treatment Really Works?

 

How Is Glaucoma Diagnosed?

One of the most important things to understand about glaucoma is that there is no single test that can diagnose it.

Instead, your optometrist considers the results of several examinations to build a complete picture of your eye health.

Because glaucoma often develops gradually and without symptoms, these tests can identify early changes long before you notice any problems with your vision.

A comprehensive eye examination allows your optometrist to assess your risk, monitor any changes over time and recommend further investigation or treatment if necessary.

What Tests Are Used to Detect Glaucoma?

Depending on your age, symptoms, risk factors and clinical findings, your optometrist may perform several assessments during a comprehensive eye examination.

Measuring Eye Pressure (Tonometry)

One of the most recognised glaucoma tests is tonometry, which measures the pressure inside your eye, known as intraocular pressure (IOP).

Although increased eye pressure is an important risk factor for glaucoma, it does not automatically mean you have glaucoma.

Likewise, some people with glaucoma have eye pressure within the normal range.

For this reason, tonometry is only one part of a complete glaucoma assessment.

Examining the Optic Nerve

Because glaucoma damages the optic nerve, carefully examining this structure is one of the most important parts of detecting the disease.

During your eye examination, your optometrist will assess the appearance of the optic nerve for any signs of damage or changes that may suggest glaucoma.

In many cases, photographs of the optic nerve may also be taken to help monitor changes over time.

Comparing these images at future appointments allows even small changes to be detected more accurately.

Visual Field Testing

One of the earliest effects of glaucoma is the gradual loss of peripheral (side) vision.

A visual field test measures how well you can detect objects throughout your field of vision.

The test is painless and helps identify areas of vision loss that you may not notice during everyday activities.

Visual field testing is commonly used both to diagnose glaucoma and to monitor whether the condition remains stable over time.

Optical Coherence Tomography (OCT)

Modern eye care has transformed the way glaucoma can be detected and monitored.

One of the most valuable technologies available today is Optical Coherence Tomography (OCT).

OCT uses light waves to create highly detailed cross-sectional images of the retina and optic nerve without touching the eye.

These images allow eye care professionals to measure the thickness of the retinal nerve fibre layer and detect structural changes that may occur before noticeable vision loss develops.

Not every practice has the same diagnostic equipment, and your optometrist will recommend the most appropriate investigations based on your individual needs.

Measuring Corneal Thickness

Some patients may also have their corneal thickness measured.

This is important because the thickness of the cornea can influence eye pressure measurements.

Understanding corneal thickness helps your optometrist interpret eye pressure results more accurately and contributes to a more complete glaucoma risk assessment.

Why Regular Monitoring Is So Important

Glaucoma usually develops slowly over many years.

Rather than relying on a single examination, your optometrist often compares the results of several visits to identify whether meaningful changes are occurring.

Monitoring may include comparing:

  • Eye pressure measurements
  • Optic nerve appearance
  • Visual field results
  • Retinal imaging
  • Overall eye health

This long-term approach helps detect progression early and guides treatment decisions.

How Is Glaucoma Treated?

Although glaucoma cannot currently be cured, effective treatment can often slow or prevent further damage to the optic nerve.

The main goal of treatment is to reduce the risk of additional vision loss by lowering eye pressure where appropriate and monitoring the condition carefully over time.

Treatment depends on:

  • The type of glaucoma
  • The severity of the disease
  • Your eye pressure
  • The health of your optic nerve
  • Your overall medical history

Eye Drops

Prescription eye drops are often the first treatment recommended for glaucoma.

These medications work by either:

  • Reducing the amount of fluid produced inside the eye, or
  • Improving the drainage of fluid from the eye.

Using glaucoma eye drops exactly as prescribed is extremely important because missing doses may reduce their effectiveness.

Laser Treatment

Some patients may benefit from laser procedures that improve fluid drainage within the eye.

Laser treatment is generally performed by an ophthalmologist and may be recommended depending on the type and stage of glaucoma.

Surgery

For some people, surgery may be necessary if eye drops or laser treatment do not adequately control the condition.

Several different surgical procedures are available, and your ophthalmologist will recommend the most appropriate option based on your individual circumstances.

Living Well With Glaucoma

Being diagnosed with glaucoma can feel overwhelming, but many people continue to enjoy excellent vision throughout their lives with appropriate treatment and regular follow-up.

The most important factors are:

  • Attending regular eye examinations
  • Using prescribed treatment consistently
  • Reporting any changes in vision promptly
  • Maintaining ongoing communication with your eye care team

Early diagnosis and long-term monitoring remain the most effective ways to protect your sight.

Did You Know?

Glaucoma treatment is designed to protect the vision you still have.

Because damage to the optic nerve is usually permanent, early detection and timely treatment are far more effective than waiting until symptoms develop.

Regular comprehensive eye examinations are one of the best ways to detect glaucoma before symptoms develop. They also play an important role in diagnosing conditions such as Dry Eye Disease, retinal disorders and other common eye conditions.

Why Choose First Choice Vision?

At First Choice Vision, we believe that protecting your sight begins with early detection.

Our experienced optometrists provide comprehensive eye examinations using evidence-based clinical assessment to identify early signs of glaucoma and many other eye conditions before symptoms develop.

Every patient receives personalised care based on their individual risk factors, eye health and visual needs. When additional investigation or specialist care is required, we work closely with your GP and ophthalmologist to support ongoing management and continuity of care.

We proudly care for patients across:

  • St Albans
  • Sunshine
  • Sunshine North
  • Sunshine West
  • Keilor
  • Keilor Downs
  • Caroline Springs
  • Taylors Lakes
  • Deer Park
  • Delahey
  • Sydenham
  • Albanvale
  • Derrimut
  • Ardeer
  • Melbourne's western suburbs

Protect Your Vision with Regular Eye Examinations

Glaucoma often develops silently, without pain or noticeable symptoms. By the time vision changes become obvious, permanent damage may already have occurred.
Regular comprehensive eye examinations remain the most effective way to detect glaucoma early, assess your individual risk and monitor your long-term eye health.
If it's been some time since your last eye examination, or if you have a family history of glaucoma, booking an appointment with your optometrist is one of the most important steps you can take to protect your vision.

FAQs

Your Most Common Questions Answered.

What is glaucoma?

Glaucoma is a group of eye diseases that damage the optic nerve, usually over many years. The optic nerve carries visual information from your eye to your brain, and damage to this nerve can lead to permanent vision loss if left untreated.

Currently, there is no cure for glaucoma.

However, early diagnosis and appropriate treatment can often slow or prevent further damage, helping many people maintain useful vision throughout their lives.

Most people with early glaucoma have no noticeable symptoms.

As the disease progresses, gradual loss of peripheral (side) vision may occur. Because these changes develop slowly, many people are unaware they have glaucoma until it is detected during a comprehensive eye examination.

No.

High eye pressure is an important risk factor, but not everyone with elevated eye pressure develops glaucoma.

Likewise, some people develop glaucoma despite having eye pressure within the normal range.

This is why a comprehensive eye examination includes much more than measuring eye pressure alone.

Yes.

Having a close family member with glaucoma increases your risk of developing the condition.

If a parent, brother, sister or child has glaucoma, regular comprehensive eye examinations become even more important.

Yes.

Optometrists play an important role in the early detection and ongoing monitoring of glaucoma.

During a comprehensive eye examination, your optometrist may assess your eye pressure, optic nerve, peripheral vision and overall eye health. If glaucoma is suspected, additional investigations or referral to an ophthalmologist may be recommended.

The appropriate schedule depends on your age, family history, general health and individual risk factors.

Your optometrist can recommend a personalised review schedule based on your eye health and clinical findings.

Yes.

If glaucoma is left untreated, it can cause irreversible vision loss and, in advanced cases, blindness.

The good news is that early detection and ongoing management significantly reduce this risk for many people.

Trusted Resources

The information in this guide is based on current evidence-based recommendations from leading eye care organisations.

For further information, visit:

Disclaimer

The information in this article is intended for general educational purposes only and should not replace personalised advice from a qualified optometrist, ophthalmologist or other healthcare professional.

If you have concerns about your vision or believe you may be at increased risk of glaucoma, arrange a comprehensive eye examination with your optometrist.

About First Choice Vision

First Choice Vision is an independent optometry practice in St Albans, Melbourne, providing comprehensive eye examinations, children’s eye care, dry eye assessments, myopia management, contact lens services and personalised eye care for patients of all ages.

Our commitment is to deliver evidence-based eye care, honest advice and personalised solutions that help protect your vision throughout every stage of life.

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