Glaucoma: causes, symptoms and treatment

What is glaucoma?

Glaucoma is a common eye condition that can lead to irreversible sight loss. It occurs when normal fluid in the eye doesn’t drain properly, which builds up and increases the pressure within the eyeball. This pressure damages the optic nerve that connects the eye to the brain. If left untreated, blood vessels in the eye can also narrow and even burst.

Worldwide, 3.6 million people are estimated to be blind because of glaucoma, making it the second highest cause of blindness. While it can take years for symptoms to appear, early diagnosis and treatment are key to managing the condition.

Types of glaucoma

The main types of glaucoma are:

• Primary open-angle glaucoma is the most common form. The channels that drain fluid from the eyes become clogged, causing an increase in pressure. A person may have few warning signs, but if caught early, this form of glaucoma generally responds well to medication.
• Acute angle-closure glaucoma often occurs in people with smaller eyes, where blockages are more likely. It causes sudden, intense symptoms that require urgent treatment: medication to lower the pressure is usually needed before surgery can be carried out to correct the issue.
• Secondary glaucoma is usually caused by an injury to the eye, illness or taking certain types of medication, such as steroids.

What are the symptoms?

Typically, people with the most common form of glaucoma don’t experience any symptoms until the later stages of the disease, when severe damage to the optic nerve has already occurred.

Early signs of the condition can be missed without regular eye tests every two years. If left untreated, glaucoma can progress and cause permanent visual impairment and blindness. This can happen within 10 to 20 years.

Signs of glaucoma include:

• Blurred vision
• Coloured halos around bright lights
• Blind spots
• Tunnel vision (also known as peripheral vision loss), where you lose sight at the edges of your field of vision

People with acute angle-closure glaucoma, which is less common, may experience sudden pain and redness in the eyes and severe headaches. Those with secondary glaucoma may also experience symptoms.

Can glaucoma be cured?

Glaucoma can’t be cured, and vision that’s already been lost cannot be restored. But medication and surgery can help prevent further sight loss. Every patient with glaucoma requires lifelong treatment to manage the condition.

What we’re doing to tackle glaucoma

Sightsavers treats and prevents eye conditions including glaucoma in the countries where we work.

Yet the challenge is that patients often don’t seek treatment for glaucoma until it is too late to save their sight. This is why we are working with partners in Africa and India to introduce pilot programmes to prevent and treat glaucoma.

Our aim is to make sure glaucoma is diagnosed and treated as part of local eye health services where people can be screened regularly, to ensure patients’ sight can be saved.

With your support, we can reach more people by working with governments to improve eye care services and ensure everyone can access vital treatment.

Page last reviewed: January 2025
Next review due: January 2028
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