Glaucoma is a complicated disease, but over the last few decades, advances in technology mean that we have more efficient ways to detect and diagnose it. The best thing about them? They’re usually part of your eye test.

Diagnosing glaucoma

The information in this hub is here to help you understand exactly how glaucoma is detected and diagnosed.

From tackling issues such as eye test fears, to breaking down the multiple types of glaucoma, to detecting early signs using an OCT scan, we’ll talk you through exactly what happens during the glaucoma diagnosis process. 

Learn more about glaucoma causes, whether or not it’s preventable, and glaucoma treatment options here. Or you can visit our glaucoma hub for more information on glaucoma symptoms.

Glaucoma tests

There are a few ways we check for signs of glaucoma when you come in for an eye test.

We’ll carry out a few tests before you go in to see the optician, then your optician will do some more checks during your appointment. All these tests include: 

  • Tonometry – sometimes known as the ‘puff of air’ test, this measures the pressure within your eye (intraocular pressure). A consistently high pressure is one of the main risk factors for developing glaucoma. Other forms of tonometry might be used that measure eye pressure differently, using drops and a probe.
  • Digital retinal photography – this involves taking a picture of your eye with a specialist camera that gives the optician a good view of the retina and your optic nerve at the back of the eye. Your optician will pay special attention to the optic nerve as that’s typically where glaucoma presents itself. The images from your previous visits are used to compare the current appearance of the eye to check for changes that may indicate glaucoma. 
  • Optical coherence tomography (OCT) – an OCT scan creates a 3D image of the eye and all the layers inside, which gives your optician an even greater idea of what’s going on beneath the surface. OCT can even help opticians to spot glaucoma up to four years earlier than more traditional methods.
  • Visual field test – glaucoma generally affects your peripheral vision to start with, so this is a way to assess this vision in each eye. It normally involves counting flashing lights and pressing a button whenever you see one.

You can read more about these tests here.

High intraocular pressure

Everyone has fluid inside their eyes, which is regulated by tiny tubes and drainage channels in the eye. Sometimes these channels can become blocked or don’t work as well, which can cause the pressure in the eye (intraocular pressure) to rise.

A high intraocular pressure can be a significant risk factor of developing glaucoma. If the pressure is consistently high, it can start to affect the sensitive nerve fibres at the back of the eye. The issue is that these changes happen slowly and, in most cases, the increase it pressure doesn’t hurt – so for many people it’s impossible to know there might be problems until it has caused irreversible damage to their vision. That’s why having regular eye tests is so important, so we can keep an eye on your pressure levels every time you see us, alongside all the other eye health checks we carry out. 

Often people will have a high intraocular pressure naturally and it doesn’t always lead to any eye problems, but it’s important to keep monitoring your pressure over time with eye regular tests, just in case.

If your optometrist feels that the pressure in your eyes is unusually high, or it’s high and causing damage to the nerves, they’ll refer you to a specialist for further investigation. Being referred doesn’t always mean that you have glaucoma, just that your optometrist would like to run a couple more tests to make sure.

Read more articles about glaucoma diagnosis