Glaucoma, the leading cause of irreversible blindness in the world: can it ever be cured?

3.5% of the population between the ages of 40 and 80 suffer from glaucoma. And this is a lot. To give us an idea, 111 million people will suffer in 2040 from this serious neurodegenerative disease that affects the optic nerve, the first cause of irreversible blindness in the world.

One of the main problems of glaucoma is that vision loss begins in the periphery of the visual field and it is not noticeable; hence its nickname of “silent disease”. When we detect this loss, approximately half of the neurons have already died and we cannot recover them, as it happens in alzheimer.

fatal pressure

Among the different types of existing glaucoma, the so-called open-angle glaucoma is the one that most affects the European population. It is characterized by an increase in intraocular pressure, generated when there is more fluid than due inside the eye. Said liquid, in charge of feeding the cells inside the visual organ, must be produced and eliminated at a rate that maintains normal pressure.

If the cells in charge of generating it (ciliary body) do so above their optimal level or the evacuation encounters some impediment in the filtering process, then the pressure increases. Loss of vision appears when this push is transmitted to the retina, the nervous part of the eye –located in the back area–, and the cells that carry the visual message to the brain die.

Female doctor doing cataract surgery in operating room - Reference image
Female doctor doing cataract surgery in operating room – Reference image – Photo: Getty Images

How is glaucoma treated?

Treatments are aimed at stopping the progress of the disease by lowering intraocular pressure. However, today it is not possible to reverse and recover the already lost vision. The order of therapies to prevent progression is:

  • Medications in the form of drops, generally aimed at reducing the production of aqueous humor or improving the drainage of said fluid.
  • Laser therapies on the channel through which the fluid drains. The goal is to increase said drainage and reduce intraocular pressure when the drops have no effect.
  • Surgery to increase the opening of a drainage area or the leakage of aqueous humor (trabeculectomy) or to implant a drainage device. It is used when the two previous phases no longer manage to lower intraocular pressure.
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ongoing investigations

Despite having passed more than 150 years since the discovery of glaucoma, we have not been able to unravel why it occurs and how it progresses. It is true that techniques to reduce pressure have improved, but we still do not know how to protect or regenerate lost neurons.

Ophthalmologist examining patient's eyes - Reference image
Ophthalmologist examining patient’s eyes – Reference image – Photo: Getty Images

To study any disease it is necessary to analyze what is happening and test the treatments in animals before they reach humans. Thus, in 2004, our working group developed a model of glaucoma in pigs Thanks to funding from the American Foundation The Glaucoma Foundation.

We chose this animal because its eye is very similar to a human’s. Currently, this model is being used to design devices that lower intraocular pressure.

We also develop other systems easier to apply in laboratory animals such as rats. denominated in English microbeads method (microsphere method), is the most widely used experimental glaucoma model in the world and allows progress in the knowledge of the mechanisms that cause the death of neurons.

He Investigation Group that I currently direct has also been a pioneer in the neuroprotection study. That is, to quantify whether, apart from reducing intraocular pressure, the treatments protect neurons from death in glaucoma. In addition, we have collaborated with pharmaceutical companies to develop longer-lasting and easier-to-apply treatments – especially for the elderly and children – using RNA interference technologies. This would replace the daily drops prescribed in classical therapies.

And finally, we have recently discovered the role played in glaucoma by the most abundant cells in the retina, called Mullerian gliawhich function as pressure sensors. In a normal state, they secrete factors that protect the neurons of the retina, but we have shown that when intraocular pressure increases, they are altered and are the triggers for the death of neurons that cause blindness in glaucoma. those cells appear as (G) in the schematic.

Doctor and patient in ophthalmology clinic - Reference image
Doctor and patient in ophthalmology clinic – Reference image – Photo: Getty Images
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This proposal is very novel and may have an impact on the future of glaucoma treatments. We have just presented the results in the European Vision and Eye Research Meeting. Accepted in the most prestigious international conference in the field of vision (ARVO), will be published very soon in a high-impact scientific journal.

Undoubtedly, with more investment in research we will be able to cure glaucoma and restore sight to those who have lost it due to it. A long and hopeful road awaits us.

By: Elena Neighbor Lamb

Professor of Cellular Biology (UPV/EHU), IdEX Prof. Univ. Bordeaux (France), Life Member Clare Hall Cambridge (UK). Director of the Experimental Ophthalmo-Biology Group (GOBE), University of the Basque Country / Euskal Herriko Unibertsitatea

Article originally published in The Conversation

The Conversation

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