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Glaucoma: What it is, Symptoms, Causes, Types & Treatment

Glaucoma is often called the “silent thief of sight” because it can damage your vision gradually, without noticeable symptoms in the early stages. It is a leading cause of irreversible blindness worldwide. However, with timely detection, proper treatment, and regular follow-up care, glaucoma can often be managed to protect your vision.

Knowledge is a key part of prevention. This detailed guide explains what glaucoma is, why it develops, its symptoms, types, and the treatments available.

What is glaucoma?

Glaucoma is not a single disease but a group of eye conditions that damage the optic nerve — the nerve responsible for transmitting visual information from your eye to your brain.
Most commonly, this damage occurs when fluid inside the eye (aqueous humour) does not drain properly, causing increased intraocular pressure (IOP). However, some people develop glaucoma even with normal eye pressure.

Over time, untreated glaucoma can lead to permanent loss of peripheral vision and, eventually, central vision.

Why does early detection matter?

Because glaucoma can progress without pain or noticeable vision changes at first, many people are unaware they have it until significant damage has occurred. Early detection through comprehensive eye exams is the most effective way to prevent vision loss.

We use advanced diagnostic technology to detect glaucoma at its earliest stages, when treatment is most effective.

Symptoms of glaucoma

The symptoms of glaucoma depend on the type and stage of the disease.

Early stages

Often no symptoms.
Subtle changes in side (peripheral) vision.

Progressive stages

Loss of peripheral vision. (tunnel vision)
Difficulty seeing in low light.
Needing more light for reading or close work.

Acute Angle-Closure Glaucoma (Medical Emergency)

Sudden, severe eye pain.
Headache
Nausea and vomiting.
Blurred vision or halos around lights.
Redness in the eye.

If you experience sudden eye pain, vision loss, or nausea with eye redness, seek emergency medical care immediately.

Causes and risk factors

Glaucoma develops when the optic nerve becomes damaged, usually due to high intraocular pressure. However, optic nerve weakness, poor blood flow, and genetic factors may also play a role.

Major causes and risk factors include:

High intraocular pressure. (primary cause)
Age – more common over 40, especially after 60.
Family history – increases risk significantly.
Ethnicity – people of African, Asian, or Hispanic descent have higher risk for certain types.
Eye injury – past trauma can lead to secondary glaucoma.
Prolonged steroid use – eye drops, tablets, or inhalers.
Other health conditions – such as diabetes, hypertension, or migraine.
Thin corneas – may increase susceptibility to optic nerve damage.

Types of Glaucoma

1. Primary Open-Angle Glaucoma (POAG)

This is the most common form of glaucoma, often called the “silent thief of sight” because it develops very slowly and without noticeable symptoms in the early stages. It occurs when the drainage canals of the eye gradually become less efficient, causing a slow build-up of intraocular pressure (IOP). Over time, this pressure damages the optic nerve, leading to a gradual loss of peripheral (side) vision. Because vision loss happens so subtly, many people are unaware of the disease until it has progressed significantly. POAG is usually detected during routine eye exams, highlighting the importance of regular check-ups.

2. Angle-Closure Glaucoma

Angle-closure glaucoma is less common than POAG but is considered more severe and vision-threatening. It occurs when the drainage angle between the iris (the colored part of the eye) and the cornea (the clear outer layer) becomes blocked. This blockage prevents fluid from draining properly, causing a rapid and dangerous rise in eye pressure.

Acute angle-closure glaucoma develops suddenly and is a medical emergency. Symptoms include severe eye pain, headache, blurred vision, nausea, and halos around lights. Without prompt treatment, it can cause permanent vision loss.
Chronic angle-closure glaucoma develops more gradually and may not cause obvious symptoms until significant damage has occurred.

3. Normal-Tension Glaucoma

In this form of glaucoma, optic nerve damage occurs even though the eye pressure is within the normal range. The exact reason is not fully understood, but reduced blood flow to the optic nerve may play a major role. NTG is often detected through routine eye exams when doctors notice optic nerve damage or visual field loss despite normal intraocular pressure. Risk factors include a family history of glaucoma, low blood pressure, migraines, or conditions that affect circulation. Since eye pressure is not elevated, diagnosis can sometimes be delayed, making regular comprehensive eye exams crucial.

4. Secondary Glaucoma

This type of glaucoma develops as a complication of another eye condition, injury, or external factor. Some common causes include:

Eye injury or trauma that disrupts fluid drainage.
Inflammation inside the eye (uveitis).
Advanced cataracts that block fluid flow.
Tumors that obstruct drainage structures.
Steroid medication use, especially long-term use of eye drops, tablets, or inhalers.

Secondary glaucoma can mimic either open-angle or angle-closure glaucoma, depending on the underlying cause. Treatment focuses on controlling eye pressure and addressing the root condition.

5. Congenital Glaucoma

Congenital (or childhood) glaucoma is a rare form present at birth or developing in early childhood due to abnormal development of the eye’s drainage system. Unlike adult glaucoma, it often shows noticeable symptoms, including:

Cloudy or enlarged corneas
Excessive tearing
Extreme sensitivity to light (photophobia)

Parents may notice that the baby’s eyes look unusually large or watery. Because the disease can cause rapid vision loss, early diagnosis and surgical treatment are critical to prevent permanent damage.

How is glaucoma diagnosed?

Glaucoma cannot be detected by a simple vision check alone. It requires a set of advanced tests to accurately identify the disease in its early stages, since vision loss from glaucoma is often gradual and painless. The main diagnostic methods include:

Tonometry – This test measures the intraocular pressure (IOP) inside the eye. Elevated eye pressure is one of the biggest risk factors for glaucoma, though glaucoma can also occur with normal pressure.
Optical Coherence Tomography (OCT) – A non-invasive imaging technique that provides high-resolution, cross-sectional pictures of the optic nerve and retinal nerve fiber layer. It helps in detecting early structural damage before vision loss occurs.
Visual Field Testing – This test checks for blind spots and peripheral vision loss, which are often the first functional signs of glaucoma. Regular testing helps track disease progression over time.
Gonioscopy – A special lens is used to examine the drainage angle of the eye (where fluid exits). This helps determine whether the glaucoma is open-angle or angle-closure, which guides treatment.
Pachymetry – This measures the thickness of the cornea. Since corneal thickness can affect the accuracy of pressure readings, pachymetry ensures that intraocular pressure is interpreted correctly.

These tests are painless, quick, and crucial for detecting glaucoma early.

Treatment options for glaucoma

Although there is no cure for glaucoma, early and ongoing treatment can help prevent or slow vision loss.

1. Medications

Eye Drops – These are usually the first-line treatment. They work either by reducing the amount of fluid (aqueous humor) the eye produces or by helping the fluid drain out more efficiently. Different classes of eye drops (such as prostaglandin analogs, beta-blockers, alpha agonists, and carbonic anhydrase inhibitors) may be used individually or in combination.
Oral Medications – If eye drops alone do not control pressure adequately, doctors may prescribe oral medicines such as carbonic anhydrase inhibitors. These reduce fluid production in the eye but are usually reserved for short-term or additional control, as they can have more systemic side effects.

2. Laser Treatments

Selective Laser Trabeculoplasty (SLT) – Commonly used for open-angle glaucoma. A laser is applied to the trabecular meshwork (the eye’s drainage system) to improve fluid outflow, lowering pressure. It is a quick outpatient procedure with minimal discomfort and can sometimes reduce or replace the need for daily drops.

Laser Peripheral Iridotomy (LPI) – Used mainly for angle-closure glaucoma. The laser creates a tiny hole in the iris (the colored part of the eye) to allow fluid to flow more freely, relieving pressure and preventing sudden attacks of high eye pressure (acute angle closure).

3. Surgery

Minimally Invasive Glaucoma Surgery (MIGS) – A group of newer procedures that use tiny stents, shunts, or devices inserted into the eye’s drainage pathways. These surgeries are less invasive, have quicker recovery times, and are often combined with cataract surgery. They are usually recommended for mild to moderate glaucoma.
Trabeculectomy – A traditional surgery where the surgeon creates a new drainage channel under the eyelid, allowing fluid to bypass the clogged drainage tissue and lower pressure. It is often recommended for advanced glaucoma or when other treatments fail.
Drainage Implants (Tube Shunts) – A small tube connected to a reservoir is implanted in the eye to divert fluid and maintain safe pressure levels. These are typically used in cases where trabeculectomy or other methods have not worked or are unsuitable.

Your treatment plan at Clarity Eye Surgeons will be customised based on your type of glaucoma, severity, and lifestyle needs.

Living with glaucoma

Managing glaucoma is a lifelong process. Key steps to protect your vision include:

Attending all scheduled follow-up visits.
Using prescribed medications exactly as directed.
Reporting any changes in vision immediately.
Maintaining a healthy lifestyle to support eye health.

When to see an eye specialist?

You should have regular comprehensive eye exams every 1–2 years after age 40, or earlier if you have risk factors for glaucoma. Early diagnosis offers the best chance to preserve vision.

Conclusion

Glaucoma does not have to mean losing your sight — but it does require ongoing care. At Clarity Eye Surgeons, we combine advanced technology, precise diagnosis, and personalised treatment plans to help you manage glaucoma effectively.

Book your glaucoma evaluation today and take the first step towards safeguarding your vision for life.

Author Bio

Dr Parth Shah is a director and principal ophthalmologist at Clarity Eye Surgeons in Canberra. With extensive training and experience, he is renowned for his expertise in the field. Dr Shah is dedicated not only to performing successful surgeries but also to patient education. His compassionate approach, combined with technical proficiency, has earned him the trust and gratitude of countless patients. He is a true advocate for eye health and a trusted name in the Canberra ophthalmology community.

FAQs

Can glaucoma be prevented?

While glaucoma cannot always be prevented, regular eye exams, maintaining a healthy lifestyle, and controlling risk factors like high blood pressure and diabetes can help reduce the risk of vision loss.

Does glaucoma always affect both eyes?

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Is vision lost from glaucoma reversible?

Unfortunately, any vision loss from glaucoma is permanent. However, treatment can slow or stop further damage.

Can lifestyle changes help manage glaucoma?

Yes. Regular exercise, a balanced diet rich in antioxidants, avoiding smoking, and protecting your eyes from injury can support overall eye health.

Do glasses or contact lenses help treat glaucoma?

No. While glasses and contact lenses can correct refractive errors, they cannot treat or slow glaucoma progression.

Is glaucoma more common in men or women?

Some studies suggest certain types of glaucoma are more common in women, while others affect both genders equally. The risk depends more on age, ethnicity, and medical history than gender alone.