A new study conducted in rats shows that chemical known to protect nerve cells also slows glaucoma, the leading cause of irreversible blindness. Led by researchers at NYU Grossman School of Medicine, the study centers on the watery fluid inside the eye on which its function depends. Fluid pressure can build up in patients with glaucoma, wearing down cells in the eye and the nerves connecting them to the brain, researchers said. However, past studies have shown the condition to continue to worsen even after eye pressure has been controlled. The connection between pressure buildup and impaired vision remains poorly understood. Published in Neurotherapeutics, the new study showed that ingesting the compound citicoline restored optic nerve (neural) signals between the brain and eye to near-normal levels in the study rats. Naturally produced in the brain but also available commercially, citicoline is a major source of choline, a building block in the membranes that line nerve cells and enhance nerve cell communication. While the study results confirmed past findings that elevated eye pressure contributes to nerve damage in glaucoma, it also showed that citicoline reduced vision loss in rats without reducing fluid pressure in the eye. The findings are helping scientists better understand how glaucoma works and add to past evidence that citicoline may counter the disease, said Chan, also the director of the Neuroimaging and Visual Science Laboratory at NYU Langone. Previous studies had showed that humans and rodents with glaucoma have lower than normal levels of choline in the brain. Until now, Chan said, there has been little concrete evidence of the effectiveness of choline supplements as a therapy for glaucoma or why choline occurs in lower levels in glaucoma patients. The researchers caution that more research is needed before turning to citicoline supplements to treat glaucoma in humans, as commercial drugs have yet to be proven fully effective in clinical trials. Moving forward, the researchers plan to investigate the origin of choline decline in people with glaucoma as well as how citicoline works to repair the damage.