A teenager from Trujillo, Peru, impacted by glaucoma

Glaucoma: Causes, Symptoms, Treatment

According to the International Agency for the Prevention Blindness glaucoma is the third leading cause of blindness and the fourth leading cause of vision loss in the world, affecting over seven million people. But what is glaucoma, how is it caused and what can be done to treat or prevent it?

Read below to find out more and discover what our eye care teams are doing to help fight glaucoma in communities around the world.

What Is Glaucoma?

The International Agency for the Prevention of Blindness tells us the term ‘glaucoma’ relates to a group of conditions that can be classified in a variety of ways, but all of which are characterized by optic nerve damage and visual field loss.

The human eye is filled with a clear liquid which is made continuously and then drained away, always keeping the same amount of liquid in the eye.

Glaucoma: Diagram of a normal eye with no pressure build up

Diagram of a normal eye with no pressure build up

When the opening that allows the liquid to drain is closed, more and more liquid will build up in the eye increasing the pressure. Over time, this increased pressure can damage the eye and cause reduced vision and then blindness which cannot be reversed.

Glaucoma Diagram: How pressure is building up in the eye

Diagram of glaucoma: How pressure builds up in the eye which can cause damage and sight loss

Imagine your eye is like a water tank – water flows in and water flows out. If the outlet is blocked, water cannot flow out, and the water tank will burst. To correct this, you must fix the outlet or put in a new outlet.

- The Eye Book, An Illustrated Guide For Patient Education (Orbis)

Orbis Eye Book: Glaucoma Water Tower Analogy and Diagram

Orbis Eye Book water tank analogy

Types of Glaucoma

There are several types of glaucoma, these are:

  • Primary Open Angle Glaucoma (POAG) which develops from an unknown cause
  • Primary Angle Closure Glaucoma (PACG) which develops from an unknown cause and can cause a lot of pain
  • Secondary glaucoma which develops from a known cause, usually due to a serious eye injury, cataract, tumor, or diabetes
  • Developmental (Congenital) glaucoma is a rare condition which occurs in babies and children

Causes of Glaucoma

There are a number of risk factors which can cause the development of glaucoma. These include:

  • Elevated eye pressure
  • Increasing age
  • Family history of glaucoma
  • Ethnic background
  • Eye injury
  • Diabetes
  • Hyperopia (farsightedness)
  • High myopia (shortsightedness)

Glaucoma affects both adults and children. However the condition is more common in older age.

Symptoms of Glaucoma

Different types of glaucoma present different symptoms.

Open Angle Glaucoma doesn't usually cause any symptoms to begin with. That's why eye screenings are so important for early detection. The condition tends to develop slowly over many years and affects the edges of peripheral vision first. Signs and symptoms include:

  • Gradual loss of peripheral vision, usually in both eyes
  • Tunnel vision in the advanced stages

With Angle-Closure Glaucoma which can develop very suddenly. Signs and symptoms include:

  • Sensitivity to light
  • Nausea and vomiting
  • Cloudy eyes
  • Halos around lights
  • Severe eye ache
  • Watery and reddening eyes
  • Poor vision and jerky eyes known as nystagmus

(Source: International Glaucoma Association)

Our friends at the College of Optometrists have created a video to show what the world would look like if you were affected by Glaucoma. Experience it below.

College of Optometrists : Discover what it’s like to have glaucoma through a patient’s eyes

The image gallery below shows vision loss caused by glaucoma over time.

Treatment of Glaucoma

There are no traditional treatments that can cure glaucoma but there are treatments that can control sight loss. Frequent eye screenings are critical for early detection and intervention.


There are eye drops available to reduce the pressure in the eye. These drops must be used on a regular basis. The pressure inside the eye and side vision must be checked regularly too.


Laser treatment opens up the blocked drainage tubes or reduce the production of fluid in your eyes. During treatment, a high-energy beam of light is carefully aimed at part of the eye to stop fluid building up inside it.


If eye drops and laser surgery are ineffective, surgery is advised. The most common type of surgery for glaucoma is called trabeculectomy which involves removing part of the eye-drainage tubes to allow fluid to drain more easily.

In infants, an operation is frequently performed to make small openings in the eye, allowing the extra fluid to drain.

What We’re Doing to Combat Glaucoma Around the World?

According to the International Agency for the Prevention of Blindness it has been estimated that by 2020 there were approximately 76 million people with glaucoma. However, most forms of glaucoma do not show symptoms in the early stages and therefore patients often present for treatment only after vision loss has occurred. This means the number of people with glaucoma is much larger than the figures presented here.

It is estimated that by 2040 the number of people living with glaucoma-induced blindness or vision loss will rise to 112 million (Tham et al., 2014). These figures are set to rise, unless improved screening and effective treatment strategies are successful.

In many communities around the world, people lose their vision and remain irreversibly blind from glaucoma due to a lack of access to quality eye care services as well as awareness of the importance of early intervention.

This is where we step in. By using our amazing network of partners, supporters, staff, and world leading volunteers to empower local communities with the skills and resources necessary to fight blindness caused by glaucoma on their own.

Doctors performing glaucoma surgery in China, led by Orbis volunteer Dr James Brandt

Doctors performing glaucoma surgery on Chinese pediatric patient Shunwen

At Orbis, we're implementing a comprehensive approach to fighting blindness caused by glaucoma:

Training: We train local partners on our Flying Eye Hospital, in local hospitals and via Cybersight. This way we can strengthen skills and knowledge for local eye teams over all over the world for many generations.

Technology: We're running e-learning courses on Cybersight which improve knowledge and education as well as offering training and support to eye teams around the world using the latest advancements in internet and mobile technologies.

Strengthening: By working with partners across the health service to establish and strengthen existing care we help provide long-term, sustainable eye care to communities around the world. From rural areas to bustling cities, we aim to provide the tools and knowledge to help restore vision for generations to come.

Community: We want to make sure everyone has access to quality eye care, no matter where they live. This is why we work at a community level, training and educating people about early intervention especially parents to help them recognize the signs of glaucoma in newborns before it's too late.

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