What is Glaucoma? [1] [2] [3]

Glaucoma is a group of eye diseases that can cause vision loss and blindness by damaging a nerve in the back of your eye called the optic nerve. It’s usually caused by fluid building up in the front part of the eye, which increases pressure inside the eye, referred to as intraocular pressure (IOP), often because the fluid can’t drain away as it should. Glaucoma is a common eye disease affecting millions of people and is still the leading cause of irreversible blindness in the world.

Glaucoma symptoms can start so slowly that you may not notice them. Glaucoma is usually detected at a routine eye test by an optician and then your treatment is managed by an ophthalmologist (specialist eye doctor).

Over time, you may slowly lose vision, usually starting with your side (peripheral) vision — especially the part of your vision that’s closest to your nose. Because it happens so slowly, many people can’t tell that their vision is changing at first. There’s no cure for glaucoma, but early detection and treatment can often slow the progression and protect your vision. Without treatment, glaucoma can eventually cause blindness.

It can affect people of all ages, but is most common in adults in their 70s and 80s.

What is Glaucoma?

Signs & Symptoms [1] [2]

Glaucoma does not usually cause any symptoms initially. It tends to develop slowly over many years and affects the edges of your vision (peripheral vision) first. For this reason, many people do not realise they have glaucoma, and it’s often only picked up during a routine eye test.

However, if you do experience symptoms, they might include blurred vision, or seeing rainbow-coloured circles around bright lights.

Both eyes are usually affected, although it may be worse in 1 eye.
Very occasionally, glaucoma can develop suddenly and cause:

  • Intense eye pain
  • Nausea and vomiting
  • A red eye
  • A headache
  • Tenderness around the eyes
  • Seeing rings around lights
  • Blurred vision

Anyone can develop Glaucoma, but you’re at greater risk if:

  • You have a high eye pressure – Intraocular Pressure (IOP)
  • Age > 40 years
  • Thinner central cornea
  • Family history
  • Ethnicity – people of African, Caribbean or Asian origin are at a higher risk
  • Other medical conditions – such as cardiovascular disease, short sightedness, long sightedness and diabetes

There are several different types of glaucoma. The most common form of glaucoma is primary open angle glaucoma, which typically develops over many years and is often asymptomatic, meaning there are no symptoms, making it difficult to diagnose. It’s caused by the drainage channels in the eye becoming gradually clogged over time.

Other types of glaucoma include:

  • acute angle closure glaucoma – an uncommon type caused by the drainage in the eye becoming suddenly blocked, which can raise the pressure inside the eye very quickly
  • secondary glaucoma – caused by an underlying eye condition, such as inflammation of the eye (uveitis)
  • childhood glaucoma (congenital glaucoma) – a rare type that occurs in very young children, caused by an abnormality of the eye
  • Primary open angle glaucoma (POAG) affects about 2% of people in the UK older than 40 years.
  • The prevalence increases with increasing age. For example, POAG affects about 1% of people aged 40, about 3% of people aged 60, and about 8% of people aged 80 years.
  • POAG affects both sexes equally.
  • It is thought that around half of all people in the UK with POAG have not been diagnosed as people with early POAG are typically unaware that they have it.
  • Between 2015 and 2035, the number of people living with glaucoma in the UK is expected to increase by 44%.
How glaucoma affects vision

Glaucoma is an eye condition where your optic nerve is damaged by the pressure of the fluid inside your eye. This may be due to your eye pressure being higher than normal, or because of a weakness to your optic nerve. Your eye needs a certain amount of pressure to keep the eyeball healthy and in the right shape. But if the pressure is too high, it can cause your optic nerve to become damaged at the point where it leaves your eye. This damage is called glaucoma.

To determine whether you have glaucoma, several quick and painless tests can be carried out by your Optician (Optometrist) including vision tests and measurements of the pressure inside your eye. If tests suggest you have glaucoma, you should be referred to a specialist eye doctor (ophthalmologist) to discuss treatment.

It’s not possible to reverse any loss of vision that has already occurred, but treatment can  help stop your vision getting worse. The treatment in which you are recommended will depend on the type of glaucoma that you have. Options available include:

  • eye drops – to reduce the pressure in your eyes
  • laser treatment – to open up the blocked drainage tubes or reduce the production of fluid in your eyes
  • surgery – to improve the drainage of fluid


You will most likely have to go for regular check-ups where you will have your pressures (IOP) and visual fields checked to ensure your treatments are working. Depending on the severity of your condition, this can range from monthly to every 2 years. Having your IOP checked is usually painless and will feel like a quick jet of air on the surface of the eye. Visual field checks will involve you focussing on a central location and often having to respond to a flash of light that moves around the periphery of your vision.


The onset of glaucoma can be slowed down by adhering to the medication or treatment prescribed to you by your eye doctor. Your eye doctor may have to try a few different medications to see which your eyes respond to best.


Glaucoma must be diagnosed, treated & monitored under the supervision of an eye doctor.

If you have any concerns about your vision, visit your Optician or GP, or speak to your Ophthalmologist.

If you have glaucoma, early diagnosis and treatment can help stop your vision getting worse. Without treatment, glaucoma can eventually lead to blindness.

If you develop symptoms of glaucoma suddenly, go to your nearest eye casualty unit or A&E as soon as possible. This is a medical emergency that may require immediate treatment.

Glaucoma and Dry Eye

Dry eye disease and glaucoma commonly appear together. Studies suggest that 50-60% of people who are being treated for glaucoma also have dry eye disease.[5]

To find out more on how to manage your dry eye symptoms, visit the treatment and prevention section of Dry Eye and Me here:

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