Researchers have discovered a new test that can detect glaucoma progression 18 months earlier than the gold standard method used currently. Glaucoma, the leading global cause of irreversible blindness, affects over 60 million people, which is predicted to double by 2040 as the global population ages. Loss of sight in glaucoma is caused by the death of cells in the retina, at the back of the eye. The test, called DARC (Detection of Apoptosing Retinal Cells), involves injecting into the bloodstream (via the arm) a fluorescent dye that attaches to retinal cells and illuminates those that are in the process of apoptosis, a form of programmed cell death.