In some glaucoma patients, vision loss mysteriously progresses despite treatment, and new research from China points to immune cells that migrate from the digestive tract to the eyes. These "gut-retina axis" cells bind a specific protein and gain access to the eye's light-sensitive tissue, where they damage retinal ganglion cells (RGCs). Glaucoma, classified as a group of neurodegenerative diseases, is an umbrella term for eye diseases caused by loss of RGCs, whose axons form the optic nerve which transmits visual information to the brain. Your optic nerve is sending this to your brain's visual cortex to process right now, if...