What causes glaucoma and how is it diagnosed?

Written by: Miss Anna Mead
Published: | Updated: 11/12/2023
Edited by: Bronwen Griffiths

Glaucoma is a condition that damages the optic nerve, which, if left untreated, can lead to a loss of vision. Miss Anna Mead, an expert ophthalmologist, explains what causes glaucoma and how it is diagnosed in this article below. 

What is glaucoma?

Glaucoma is a condition of the optic nerve, the nerve at the back of your eye that sends your vision to your brain. Traditionally, we always thought of glaucoma as high-pressure - the pressure in the eye being too high and then damaging the optic nerve and causing you to lose your sight.

We have recently learned that although pressure plays a role, it does not necessarily have to be high in the abnormal range to cause damage. If it is too high for your eyes, then we need to lower the pressure, and we know that lowering the pressure lowers the risk of you developing glaucoma, so it is very important that you get your eye pressure checked to make sure your eye nerves stay healthy.

What causes glaucoma?

Glaucoma is caused by many factors, some of which are unknown. The biggest factor for glaucoma is the pressure in the eye - the intraocular pressure. That is the one single factor that we can try to treat and control, and that is how we manage glaucoma: by keeping the pressure down.

There is a genetic component to glaucoma as well, so if you have a family history of glaucoma you are much more likely to develop the disease. Also, people with certain conditions, such as diabetes or short-sightedness, are more likely to get glaucoma. 


How is glaucoma diagnosed?

We diagnose glaucoma traditionally by checking three important items. The first being the intraocular pressure – we must check the eye pressure to ensure it is normal. If it is high, then that increases your risk of developing glaucoma.

The second thing we look at is the visual field, looking at the peripheral field of vision, and traditionally, that test is done on each individual eye separately. The test maps out your field of vision and tells us if there is anything going on that needs treatment.

Normally, glaucoma affects your peripheral vision before it affects your central vision, so we do need to test the peripheral vision. Then, most importantly, we need to look at the optic nerve at the back of your eye in detail. The optic nerve gets damaged from the pressure, which will make it thinner, and cause a loss of nerve axon fibres. It is important that we detect these changes in the optic nerve and treat them so that they do not worsen.

We now have scanners that can scan your nerve and look at the invisible layers and tell us exactly what is going on with the optic nerve. Before we can even see a thing, the scanner will pick it up and tell us your risks. It will actually look at your nerve and compare it to a healthy individual of the same age.

We also have measurements of the wall of the eye to make sure that your wall is not thin, which is an independent risk factor for glaucoma. In addition, we have little tools that we use nowadays to look within the eye, looking at the drainage system so we can accurately assess it and look and see whether there is any blockage going on, for example. 

Can you go blind from glaucoma?

Yes, it is possible to go blind from glaucoma. The facts are that over 90 per cent of people with glaucoma will not go blind. There is a small percentage of people who go blind: about five per cent in this country, and about 10 per cent of people get functional, visual problems, but they maintain some vision.

The vast majority of people live a normal, healthy life with no problems with their vision, providing they are caught, detected and treated appropriately. The people that go blind and the people that are not caught in time are the people who do not get their eyes checked regularly for glaucoma. They are the ones that are at a higher risk of going blind. Hence, it is really important that everybody gets their eyes checked, particularly as we get older. 


If you would like to find out more about glaucoma, make sure you book an appointment today with Miss Anna Mead today. 

By Miss Anna Mead

Miss Anna Mead is a consultant ophthalmologist with exceptional knowledge and skill. She provides patients with support for a wide range of eye symptoms and conditions, most notably cataracts and glaucoma.
Miss Mead is an expert in general ophthalmology as well as specialist surgeries. She regularly performs routine and complex procedures including cataract surgery and lens replacement using intraocular lenses (IOLs). She also performs glaucoma surgeries, including MIGS (minimally invasive glaucoma surgery) and laser treatment for glaucoma.
Her undergraduate training took place at Robinson College, Cambridge, and she qualified with honours from Cambridge University Clinical School. Following her studies, she trained at several prominent eye clinics, including Moorfields Eye Hospital, a specialist NHS eye hospital, which is where she combined her clinical training with academic research by completing a PhD in glaucoma surgery. This research has led her to publish and present her work at national and international meetings.

Miss Mead has significant teaching and training experience. Among her many positions, she is currently the Head of the School for Ophthalmology for Health Education England Thames Valley (HEETV), has been a college tutor for Buckinghamshire Healthcare NHS Trust and was the HEETV Lead for Simulation tutor at the Royal College of Ophthalmologists. Here, she still provides support for struggling trainees in her Communication in Education role. 

Private patients can access Miss Mead’s outstanding care at her clinics in Great Missenden, Aylesbury and High Wycombe. She also dedicates her practice to the public sector at the Buckinghamshire NHS Trust, from which she has received a Clinical Excellence Award for her commitment to first-rate patient care.

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