Insulin may help repair damage to retinal neurons and restore sight in patients who have vision loss due to glaucoma, researchers have found, and could have applications for other neurodegenerative diseases, including Alzheimer’s.

Much of glaucoma research focuses on neuroprotection, said the Glaucoma Research Foundation which funded the study, but a team of neuroscience researchers, led by Dr Adriana Di Polo at the University of Montreal, wanted to study whether retinal neurons could regenerate with treatment after optic nerve damage.

Loss of vision in glaucoma results from the death of retinal ganglion cells (RGCs), which are composed of axons and dendrites. A crucial step towards vision repair in glaucoma is to promote damaged RGCs to regenerate not only axons, but also dendrites to successfully reconnect with their synaptic partners in the retina. The research team waited for dendritic retraction and loss of vision in a mouse model of glaucoma, then administered insulin before testing for regeneration of retinal neurons. They administered insulin via two methods, eye drops and systemic injections, and observed how the dendrites and synapses regenerated. Remarkably, researchers said, the treatment was able to not only preserve, but also to restore retinal function.

“An exciting aspect of our findings is that insulin is already in clinical use. It’s a commonly-used drug with a long history of safety and efficacy in humans,” said Dr Di Polo who is currently discussing a clinical trial with collaborators.

“We are optimistic that it has brought us one step closer to a cure for glaucoma,” said Thomas Brunner, president of the Glaucoma Research Foundation.