Glaucoma is a neurodegenerative disease: what does this mean?

Learning how to manage glaucoma can be a complex process: it’s now considered a neurodegenerative disease. This means the condition can be multi-layered, with multiple causes.

But what does this mean? Neurodegeneration sounds quite worrying — especially as it’s difficult to understand. As such, we want to break this information down into something that can be of value to those who want to understand glaucoma diagnosis more acutely.

What is a neurodegenerative disease?

Neurodegenerative disease is a term which covers a range of conditions that mainly affect the neurons in the human brain. Neurons are the building blocks of our nervous system — the brain and spinal cord — and are used to carry messages all around the body.

Neurons normally don’t replace themselves, so if they become damaged or die the body cannot replace them. This can lead to the development of various neurodegenerative diseases, such as Parkinson’s, Alzheimer’s, and Huntington’s disease.1

Some doctors now think of glaucoma as a progressive neurodegenerative disorder in which there are a number of factors. Current science shows that there is a complex connection between the eye and the brain, an important element to understanding glaucoma within the context of neurodegeneration.

Why is glaucoma considered a neurodegenerative disease?

Like Alzheimer’s and Parkinson’s disease, age and family history are significant risk factors for glaucoma. In these conditions, specific areas of the brain are damaged over time. The eye and the optic nerve are also part of the brain — they actually develop from brain cells as soon as a foetus starts to grow.

One type of cell which can be damaged by glaucoma is known as a ganglion cell. Its job is to collect ‘vision information’ from the other retinal cells. It then passes this information down an extension called an axon, through the optic nerve, and back to the rest of the brain.

Looking at glaucoma as a condition where neurons are damaged allows doctors and researchers to devise different treatments and learn from research into other conditions.

What does this mean for glaucoma patients?

Although glaucoma treatment is successful for many, there is still a small number of people who still experience vision loss.

This new way of thinking about treating glaucoma could offer these people new hope in protecting their vision.

What can we learn?

Looking at glaucoma as a progressive neurodegenerative disease can help us understand the condition more.

Right now, researchers are developing new imaging techniques — using magnetic resonance imaging (MRI) — to investigate early changes in the visual system of the brain in glaucoma patients. Their aim is to find non-invasive ways to assess the effect of ongoing high pressure in the eye on the parts of the brain involved in vision.

The research is continuing, however, not all researchers agree that glaucoma is actually a neurodegenerative disease. In fact, one study suggests that glaucoma is less likely a primary neurodegeneration affecting the central nervous system (CNS) and more likely a primary optic neuropathy with secondary effects in the CNS.2 Optic neuropathy relates to damage to the optic nerve from any cause.

What this means is that there is a still an argument between whether or not glaucoma is potentially caused from the body’s nervous system backfiring (neurons dying) and causing conditions like glaucoma, or simply as a result of damage to the optic nerve.

Regardless, the very fact that glaucoma is being discussed within the context of neurodegeneration is aiding researchers in assessing potential future treatments. Examples of these include:

● Immune modulation (harnessing the immune system to help stabilise a disease)
● Stem cell therapy (the use of stem cells to treat a disease)
● Neural regeneration (the regrowth or repair of nervous tissues and cells)

These treatments may provide further protection against the neurodegenerative processes involved in the neuron damage that some studies believe is a part of glaucoma development.3

Glaucoma is an extremely complex condition that still isn’t fully understood. Our glaucoma hub is designed to break down what we know so far for anyone who wants to know more – whether you have the condition, or you’re just interested in eye health.

References

1. Gupta N, Yücel YH.Glaucoma as a neurodegenerative disease. Curr Opin Ophthalmol. 2007 Mar;18(2):110-4.
2. Danesh-Meyer, HV. Levin, Leonard A. Glaucoma as a Neurodegenerative Disease Journal of Neuro-Ophthalmology: September 2015 - Volume 35 - Issue - p S22–S28 doi: 10.1097/WNO.0000000000000293
3. Jutley G, Luk SM, Dehabadi MH, Cordeiro MF. Management of glaucoma as a neurodegenerative disease. Neurodegener Dis Manag. 2017 Apr;7(2):157-172. doi: 10.2217/nmt-2017-0004. Epub 2017 May 22.

Satvinder Singh Soomal
BSc (HONS) MCOptom FBCLA FBDO

Satvinder has worked in the optical sector from a young age, studying the dispensing and contact lens course distance learning with ABDO… Read more