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Open angle glaucoma occurs when eye pressure is higher than normal. Here we explore what open angle glaucoma is, the two types, risk factors, symptoms and treatment for this condition.

If you have questions about open angle glaucoma and the treatment options that are available, please call us on 0203 369 2020, or request a call back.

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What is open angle glaucoma?

Open angle glaucoma is the more common of the two types of glaucoma, making up over 90% of cases. This condition is usually associated with a rise in eye pressure. Unlike with closed angle glaucoma, patients with open angle glaucoma generally display no symptoms due to the gradual nature of the increase in eye pressure.

Types of open angle glaucoma

Open angle glaucoma is divided into two types: primary and secondary. “Primary” refers to cases where the condition occurs without another identifiable cause, and “secondary” refers to cases where the condition is caused by another, separate condition.

Primary open angle glaucoma

Primary open angle glaucoma occurs when eye pressure is higher than normal. With this type of glaucoma, raised eye pressure is not caused by a narrow drainage angle. It is believed that the cause is an imbalance in the rate of aqueous fluid production in comparison to drainage rate. This causes the excess fluid to build up in the eye, therefore leading to a rise in eye pressure.

It is not fully understood why some people are more prone to primary open angle glaucoma than others, although a number of risk factors have been identified. You can read more about these in the “risk factors” section below.

Secondary open angle glaucoma

Secondary open angle glaucoma is when glaucoma is brought on by certain other conditions, with the drainage angle of the eye remaining open. Some possible secondary causes include:

  • Pigment dispersion syndrome, when the iris releases pigment. This can move to block the drainage angle
  • Pseudoexfoliation, a hereditary condition whereby white flaky material from the lens is released over time. This material can block the drainage angle
  • Neovascularisation, when blood vessels grow in parts of the eye where they would not normally be found, including areas where they can block the drainage angle
  • Uveitis and inflammation, when white blood cells collect in the eye and obstruct the drainage angle
  • Iatrogenic, when medical intervention, such as the use of tamponade gas or oil during retinal surgery, causes the eye pressure to rise
  • Trauma to the eye can damage and block the drainage angle
  • Steroid response. About 10% of people have a reaction to steroids, causing eye pressure to rise

Risk factors for open angle glaucoma

There are various factors which may increase a patient’s likelihood of developing open angle glaucoma, including:

  • Family history of glaucoma: some genetic markers have been identified, meaning that you are more likely to develop glaucoma if a close family member has the condition
  • Age: older patients are more likely to develop glaucoma
  • Race: Afro-Caribbeans are more likely to have open angle glaucoma
  • Gender: Open angle glaucoma is more prevalent in men

What are the symptoms of open angle glaucoma?

Patients with open angle glaucoma are generally asymptomatic in the early stages of the disease. This is because the reduction in visual field is so gradual. Over time if left untreated, this reduction will become more apparent and can eventually result in blindness. In fact, untreated glaucoma is the most common cause of irreversible blindness in the world.

Due to the lack of initial symptoms, open angle glaucoma is often detected incidentally during a routine eye check up. You may have experienced the “air puff” test, which is one method of quickly testing eye pressure, although it is not always accurate and further tests are required to confirm a diagnosis of glaucoma.

Open angle glaucoma treatment

There are a number of options to treat open angle glaucoma, all of which aim to either decrease aqueous fluid production, or speed up its drainage to reduce eye pressure. Treatment options include eye drops, which are normally the first line of treatment, oral medication, laser treatment or surgical treatment.

Selective laser trabeculoplasty (SLT) is an option to reduce intraocular pressure for up to 5 years, without the need for ongoing drop use. It works in this way in 75-80% of cases. It can be repeated if needed as its effects fade over time. The treatment takes 10-15 minutes per eye and side effects are very minimal.

Other treatment options include cycloiodide laser, micropulse diode laser trabeculoplasty (MDLT) trabeculectomy/tube surgery, and istent insertion.


If you suffer from glaucoma, or suspect you might have the condition, and would like to discuss potential treatment options, make an enquiry or call on 0203 369 2020

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