Dr Colin Chu and his team at the University of Bristol have successfully used a new method to switch off a particular gene in order to lower pressure in the eye to treat glaucoma.

Glaucoma is the commonest cause of irreversible blindness. It is generally caused by high pressure within the eye which silently and permanently damages the nerve connecting the eye to the brain. It is growing in prevalence and an estimated 112 million people will be affected by 2040 across the world - most likely even more. Reducing the pressure in the eye has been shown across multiple clinical trials to prevent sight loss, but no current treatment provides an optimal solution. Treatments including drops, laser, and surgery are currently used to lower eye pressure, but all of these have limitations. Eye drops have to be used every day for life, yet they are often not effective enough. Pressure lowering laser is limited in its efficacy and can itself lead to visual loss. Surgery is associated with complications which can be sight threatening and also lead to blindness. Even if it works initially, surgery often fails over time due to scarring.

Dr Colin Chu and his team at the University of Bristol have successfully used a new method (called CRISPR-Cas9) to switch off a particular gene (Aquaporin 1) in order to lower pressure in the eye. This is done using a specially designed virus that reprograms a part of the eye anatomy called the ciliary body. The ciliary body serves a number of functions including the production of aqueous humour, which, in turn, is responsible for providing oxygen, nutrients, and metabolic waste removal to the lens and the cornea, which do not have their own blood supply.

The reprogramming triggered by the virus causes the ciliary body to reduce the amount of fluid pumped into the eye, thus reducing the eye pressure. Uniquely, the treatment would be administered in a single injection and its effect should last for the rest of the person’s life. Whilst an intravitreal injection sounds invasive, it is much safer than surgery and this type of injection is now so commonly used that it is routinely administered by nursing staff in outpatient clinics.

This study builds on findings from testing done on healthy eyes and it will now use the same techniques on an experimental model of glaucoma. The study will include specific assessments to ensure the treatment protects sufficiently against nerve damage. The research team will also finish testing tissue from eyes donated for human transplantation, to be confident that the approach will work in patients. In addition, it will target two other genes (Aquaporin 4 and Carbonic anhydrase 2), to see if the reduction in pressure can be further improved.

If successful, patients could be finally free from the disadvantages of daily drop administration, but also from risk-prone surgery and even lifelong hospital monitoring. The impact for the developing world might be even greater, by providing enduring treatment of glaucoma that could be safely administered by low skilled medical staff, making this a treatment option that could be made available on a vast scale.

Read more about the causes, symptoms and current treatment of glaucoma here.

Thanks to your generous donations NERC have been able to fund this vital research. Please help us continue to fund research into glaucoma by donating to our glaucoma appeal.

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