Glaucoma is not one single eye condition. It is the name given to a group of diseases that progressively damage the optic nerve, which carries visual information from the eye to the brain.
The condition is often associated with increased pressure inside the eye, known as intraocular pressure. However, glaucoma can also develop when eye pressure appears to be within the normal range.
Glaucoma is particularly dangerous because the most common forms develop without pain or noticeable symptoms. Peripheral vision is usually affected first, meaning considerable and irreversible damage may occur before someone realises their sight has changed.
Recent research led by UCL and Moorfields Eye Hospital estimates that approximately 1.1 million people in the UK have glaucoma, equivalent to around 3% of people over 40. This rises to approximately 11% among people aged 85 and over. Researchers also believe that a substantial number of cases remain undiagnosed.
What Are the Main Types of Glaucoma?
Although every form of glaucoma damages the optic nerve, the cause, speed of progression and people most at risk can differ considerably.
Primary Open-Angle Glaucoma
Primary open-angle glaucoma is the most common form of glaucoma in the UK.
The drainage angle between the iris and cornea remains physically open, but fluid does not drain from the eye efficiently enough. Pressure may gradually increase, placing the optic nerve under stress.
This form normally develops slowly over several years and is usually painless. Most people do not experience early warning signs because the brain can compensate for small changes in peripheral vision.
Primary open-angle glaucoma is more common among:
- People over the age of 40
- People with a parent or sibling who has glaucoma
- People of African or Caribbean heritage
- People who are short-sighted
- People with diabetes
- People with raised pressure inside the eye
People of African or Caribbean heritage can develop open-angle glaucoma at a younger age and may experience more aggressive disease. This is particularly important in London, where the population is considerably more ethnically diverse than the UK overall.
Normal-Tension Glaucoma
Normal-tension glaucoma is a form of open-angle glaucoma in which optic nerve damage occurs despite eye pressure readings remaining within the statistically normal range.
It demonstrates why measuring eye pressure alone cannot rule out glaucoma. A complete glaucoma assessment should also examine the optic nerve, drainage angle, corneal thickness and visual field.
The precise cause is not always clear, although reduced blood supply or greater sensitivity of the optic nerve may contribute. Risk can be associated with increasing age, family history, low blood pressure, migraine and certain circulatory conditions.
Angle-Closure Glaucoma
Angle-closure glaucoma occurs when the iris obstructs the eye’s drainage angle. This prevents fluid from leaving the eye properly and can produce a sudden or gradual increase in pressure.
Some people develop chronic angle closure, which progresses quietly. Others experience an acute attack in which pressure rises very quickly.
Symptoms of acute angle-closure glaucoma can include:
- Severe eye pain
- A red eye
- Sudden blurred vision
- Halos around lights
- Headache
- Nausea or vomiting
Urgent warning: These symptoms require immediate medical attention. An acute angle-closure attack can permanently damage sight within a short period and should be treated as an eye emergency.
Angle closure is more common among people who are long-sighted, older adults, women and people of East or Southeast Asian heritage. London’s large Asian population means awareness of this less common but potentially sudden form of glaucoma is especially important.
Secondary Glaucoma
Secondary glaucoma develops as a result of another eye condition, injury, medical problem, medication or previous procedure.
Possible causes include:
- Eye inflammation, including uveitis
- Trauma to the eye
- Advanced diabetes
- Abnormal blood vessel growth
- Long-term use of corticosteroids
- Pigment dispersion syndrome
- Pseudoexfoliation syndrome
- Certain eye operations or lens-related complications
Secondary glaucoma may be open-angle or angle-closure, and it can develop slowly or appear more suddenly. Treatment therefore needs to control the pressure while also addressing the underlying cause wherever possible.
Anyone using steroid medication over an extended period should not stop prescribed treatment without medical advice. However, regular eye-pressure monitoring may be recommended, particularly when steroid eye drops are being used.
Childhood and Congenital Glaucoma
Childhood glaucoma is rare and may be present at birth or develop during infancy or childhood. It is usually caused by abnormal development of the eye’s drainage system.
Possible signs in babies and young children include unusually large eyes, cloudy corneas, excessive watering, light sensitivity or frequent blinking and squeezing of the eyelids.
Because a young child cannot always communicate changes in vision, early specialist assessment is essential. Childhood glaucoma often requires surgery to improve fluid drainage and protect the developing visual system.
Is Ocular Hypertension the Same as Glaucoma?
No. Ocular hypertension means that pressure inside the eye is higher than expected, but there is not currently detectable damage to the optic nerve or visual field.
Not everyone with ocular hypertension develops glaucoma. However, it is an important risk factor and usually requires continued monitoring. Treatment may be recommended when an individual’s overall risk of developing glaucoma is considered significant.
Similarly, a normal eye-pressure measurement does not necessarily mean that glaucoma is absent. Eye pressure fluctuates, and some people develop normal-tension glaucoma.
Who Gets Glaucoma in the UK?
The strongest overall risk factor is age. UK prevalence rises from approximately 0.24% among people aged 40 to 44 to around 10.6% among those aged 85 and over.
The latest national estimates suggest:
| Population |
Estimated Glaucoma Prevalence |
| UK adults over 40 |
Approximately 3% |
| People of African descent over 40 |
Approximately 4% |
| Adults aged 85 and over |
Approximately 11% |
| Estimated number currently affected in the UK |
Approximately 1.1 million |
| Projected number by 2060 |
More than 1.6 million |
These figures include different forms of glaucoma rather than describing primary open-angle glaucoma alone. The increase projected over the coming decades is expected to be driven by an ageing population and growth within groups that have a higher underlying risk.
Is Glaucoma More Common in London?
There is not one reliable figure that can be applied equally across every London borough. London’s glaucoma risk is shaped by two contrasting demographic factors.
London has a younger population than England overall, which can reduce the expected prevalence of an age-related condition. The median age in London was 35 at the 2021 Census, compared with 40 across England.
However, London is also the most ethnically diverse region of England. In the 2021 Census, only 36.8% of London residents identified as White English, Welsh, Scottish, Northern Irish or British. Around 20.7% identified within the Asian ethnic group, while London also has substantial Black African and Black Caribbean communities.
This matters because different types of glaucoma do not affect every population equally:
| Population Characteristic |
Glaucoma Relevance |
| Older London residents |
Glaucoma risk rises considerably with age. |
| African and Caribbean heritage |
Greater risk of primary open-angle glaucoma, often at a younger age. |
| East or Southeast Asian heritage |
Increased susceptibility to angle-closure glaucoma. |
| Family history of glaucoma |
Higher risk, particularly when a parent or sibling is affected. |
| High myopia |
Associated with an increased risk of open-angle glaucoma. |
| Long-sightedness |
Can increase susceptibility to angle closure. |
| Diabetes or previous eye disease |
May increase the risk of primary or secondary glaucoma. |
| Long-term steroid use |
Can cause increased eye pressure and secondary glaucoma. |
London may therefore have a younger average population, but it also contains large communities in which glaucoma can appear earlier or take a different form. The result is a complicated local picture that cannot be understood through age alone.
Why Is Glaucoma Sometimes Diagnosed Late?
The most common types of glaucoma cause little or no discomfort in their early stages. Central reading vision may remain clear while peripheral vision is gradually being lost.
Research suggests that a significant proportion of UK glaucoma remains undiagnosed. Late diagnosis is especially concerning because vision already lost to glaucoma cannot currently be restored.
People may also delay eye examinations because their vision feels normal, they do not wear glasses or they assume that a pressure check is the only test required. In reality, glaucoma detection can involve several measurements, including:
- Eye-pressure measurement
- Optic nerve examination
- Optical coherence tomography scans
- Visual-field testing
- Corneal-thickness measurement
- Examination of the eye’s drainage angle
Together, these tests provide a much more complete picture of glaucoma risk and existing optic nerve health.
When Should You Have a Glaucoma Assessment?
Regular eye examinations become increasingly important after the age of 40, particularly if glaucoma runs in your family.
You should consider a detailed assessment if you:
- Have a parent or sibling with glaucoma
- Are of African, Caribbean, East Asian or Southeast Asian heritage
- Have been told your eye pressure is high
- Are very short-sighted or long-sighted
- Have diabetes or another eye condition
- Have experienced an eye injury
- Use steroid medication over a prolonged period
- Have noticed changes in your peripheral vision
Seek urgent help: A sudden painful red eye, rapidly blurred vision, coloured halos, headache, nausea or vomiting should be treated as an emergency rather than booked as a routine appointment.
Glaucoma Diagnosis and Care in North London
At My-iClinic, our North London eye specialists use detailed diagnostic technology to assess eye pressure, optic nerve health and visual function. The purpose is not simply to identify whether glaucoma is present, but to establish the type of glaucoma, the level of risk and the most appropriate way to protect your remaining vision.
Depending on the diagnosis, glaucoma may be managed with continued monitoring, prescription eye drops, laser treatment or surgery. Early detection provides the best opportunity to slow or prevent further optic nerve damage.
If you are concerned about glaucoma, have a family history of the condition or have been told that your eye pressure is elevated, arrange a comprehensive assessment with the My-iClinic team.
References and Further Information
