Primary Glaucoma
Primary glaucomas are the most common type of glaucoma and can be split into two main types: Primary Open Angle Glaucoma (POAG) and Primary Angle Closure Glaucoma (PACG).
Primary open angle glaucoma (POAG)
Primary open angle glaucoma (POAG), also known as ‘chronic open angle glaucoma’ or just ‘open angle glaucoma’, is the most common form of glaucoma in the UK. It is estimated that about 2% of people aged 40+ have POAG, and this rises to almost 10% in people older than 75*. POAG is a slow-developing disease that causes damage to the optic nerve and is often symptomless, especially in the early stage.
To understand POAG, it’s useful to understand what glaucoma is and how drainage in the eye works.
Your eye pressure is controlled by watery fluid called aqueous humour, or just ‘aqueous’. Aqueous is made in a ring of tissue that sits behind the iris called the ciliary body. It then flows through the pupil and drains away through tiny channels called the trabecular meshwork.
The trabecular meshwork is found in the angle between the cornea and the iris (often called the drainage angle). In a normal eye, there is a balance between inflow and outflow of fluid, but in some eyes this balance is disturbed, and this causes the eye pressure to rise.
In most cases of POAG, the problem occurs due to the fluid outflow not working as well as it should. The eye can’t get rid of the fluid fast enough and the build-up results in increased eye pressure. The increase in pressure damages the optic nerve by reducing the amount of blood that can get through the tiny blood vessels and by pressing on the nerve itself.
There is also a type of glaucoma called normal tension glaucoma (NTG), which is a sub-group of POAG. This is when you have glaucoma even though your eye pressure isn’t very high. It may also be referred to as low tension glaucoma or low pressure glaucoma.
Glaucoma cannot be cured, but it can be managed effectively. Sight loss resulting from glaucoma cannot be reversed, but with effective medical treatment, the damage can be slowed or even stopped in its tracks.
More information can be found in our Primary open angle glaucoma leaflet, available for download or order.
Who is at risk of primary open angle glaucoma?
Anyone can develop primary open angle glaucoma, but some things mean it’s more likely.
Age – Primary open angle glaucoma gets more common with age. It’s uncommon below age 40 years, but rises from around 1 in 50 people over the age of 40 years to around 5 in 50 people over the age of 75 years.
Family history – Glaucoma often runs in families. As a rough guide, your brothers, sisters and children may be up to 10 times more likely to develop primary open angle glaucoma. Find out more in our booklet Glaucoma and your relatives.
Ethnicity – Compared to people of European origin, people of African-Caribbean origin are more likely to develop primary open angle glaucoma. They’re also likely to develop it at a younger age.
Short sight – People with short sight (myopia) are more likely to have primary open angle glaucoma.
Symptoms of primary open angle glaucoma (POAG)
POAG gives no warning symptoms in its early stages. There is no pain and in many cases, a person with this condition is completely unaware of the damage that is being done. This is because the typical damage occurs in the off-centre (peripheral) parts of the vision. Both eyes work together and one eye ‘fills in’ for the other so that blank patches are not noticed.
Treating primary open angle glaucoma
The aim of treating POAG is to reduce the pressure within the eye. By achieving this, it reduces pressure on the optic nerve and helps to stop further damage. Treatment is usually by eye drops. These help by reducing the fluid produced by the eye, increasing the drainage of fluid from the eye or both. You can find out more about eye drops here in our booklet ‘All about eye drops’ .
Laser is another common treatment and may be offered instead of, or in addition to eye drops.
If eye drops/ laser do not lower the eye pressure enough, surgical treatments are available.
Primary angle closure glaucoma (PACG)
Primary angle closure glaucoma (PACG) is less common in the UK but like POAG, is due to fluid being unable to drain away from the eye properly. The main difference between primary angle closure and primary open angle glaucoma is that PACG is more closely connected with the shape of the eye, and how it sits in the eye socket, whereas POAG is related to the drainage systems not working as effectively as they should.
Both PACG and POAG lead to an increase in eye pressure. The increase in pressure damages the optic nerve by reducing the amount of blood that can get through the tiny blood vessels and by pressing on the nerve itself.
To understand primary angle closure glaucoma, its useful to understand how fluid flows in and out the eye and how this is affected by reduced or narrow angles.
Your eye pressure is controlled by watery fluid called aqueous humour, or just ‘aqueous’. Aqueous is made in a ring of tissue that sits behind the iris called the ciliary body. It then flows through the pupil and drains away through tiny channels called the trabecular meshwork. The trabecular meshwork is found in the angle between the cornea and the iris (often called the drainage angle). If this drainage angle is narrow, this can reduce the effectiveness of fluid escaping the eye.
Some eyes naturally have a narrower drainage angle for example, people with smaller eyes, people who are long-sighted or people of particular ethnic origins. This smaller angle can slow down, or even close completely causing fluid to build up and eye pressure to rise.
PACG can be chronic or acute. Chronic angle closure develops slowly, usually without symptoms, as the drainage angle gets smaller and the eye pressure slowly rises. This is usually identified during a routine eye test at an optometrist. The eye doctor may use laser treatment to help prevent the narrow angle closing completely.
Who is at risk of primary angle closure glaucoma?
Anyone can develop primary angle closure glaucoma, but some things mean it’s more likely.
Age – Primary angle closure glaucoma gets more common with age. In the UK, around 20 in 5,000 people over the age of 40 years have primary angle closure. This rises to around 47 in 5,000 people over the age of 70 years.
Family history – Glaucoma often runs in families. As a rough guide, your brothers, sisters and children are around four times more likely than other people to develop primary angle closure. Find out more in our booklet Glaucoma and your relatives.
Ethnicity – Compared to people of European origin, people of east Asian origin are more likely to develop primary angle closure glaucoma.
Gender – Women are around one and a half times more likely than men to develop primary angle closure.
Long sight – People with long sight are more likely to have primary angle closure.
Symptoms of primary angle closure glaucoma
Acute primary angle closure, also known as ‘acute glaucoma’ or ‘acute angle closure glaucoma’, happens when a blockage is sudden and causes the pressure to rise very high, very quickly. Symptoms include intense pain, redness of the eye, blurred or reduced vision, headache and nausea. This tends to be very painful and it is vital that you seek medical advice immediately, as this sudden rise in eye pressure can cause permanent damage to your sight.
Sometimes, people get a series of mild attacks of angle closure. These are called ‘sub-acute’ attacks. Symptoms may include blurred vision, halos around lights and headaches. These attacks may come and go, but if this happens, it’s very important to seek immediate medical advice as it might be a warning of a future serious attack.
If you have narrow angles (where the cornea and iris meet), and are therefore at greater risk of developing PACG, this will be identified at a routine eye test.
Treating primary angle closure glaucoma
Acute angle closure is initially treated with drops and an intravenous injection to lower the eye pressure. Once the pressure is lowered, a laser or surgical procedure is carried out in order to bypass the blockage in your eye’s drainage system and prevent it happening again.
Normally, the same procedure is also performed in the other eye in order to prevent an attack of acute angle closure in that eye. These treatments are not painful and are usually carried out as an out-patient, although a short stay in hospital may occasionally be required.
If primary angle closure is diagnosed and treated without delay there may be an almost complete and permanent restoration of vision. However, any delay in addressing the problem may result in permanent damage to the affected eye. Occasionally the pressure may remain raised and ongoing treatment will be required.
Chronic angle closure glaucoma is treated in a similar way with drops to lower the pressure. In addition, laser treatment is often given to prevent further angle closure.
Let’s talk about glaucoma
If you want more information, advice or support, our helpline is available, Monday-Friday 9.30am – 5.00pm.
Call 01233 648 170 or email helpline@glaucoma.uk and our advisers will be happy to help.
Order one of our free booklets on primary glaucomas
Our information booklets are a great way to increase your knowledge. If you prefer to read print materials, you can order booklets and leaflets without charge. Digital editions are also available and below you can access our Primary Angle Closure Glaucoma and our Primary Open Angle Glaucoma booklets.
Primary Angle Closure Glaucoma
Primary Open Angle Glaucoma
You can help shape glaucoma care
Glaucoma care is changing across the UK and patient experiences should inform that change. But we need your help to make it happen.
Take part in our national survey today and tell us what is working, what needs to improve, and what really matters to you. Your experiences will provide vital evidence to help us push for better, more consistent glaucoma care.