A phase I clinical trial of DARC

A fluorescent dye injected into the arm lets doctors see dying nerve cells in the back of the eye for the first time. This matters because glaucoma, a leading cause of irreversible blindness, is usually detected only after permanent vision loss has already occurred. Current tests measure damage that has already happened, rather than spotting the disease as it begins. The technique, called DARC (Detection of Apoptosing Retinal Cells), uses a modified version of a naturally occurring human protein—Annexin—that binds to cells in the process of dying. When tagged with a fluorescent marker and injected intravenously, it makes those cells visible through the eye’s transparent structures using a standard camera. If this phase I clinical trial succeeds, DARC could become a routine screening tool in optometry clinics and GP surgeries. Instead of waiting for patients to notice blind spots, doctors could catch glaucoma years earlier, when treatment can still preserve sight. The same approach might eventually be adapted to diagnose Alzheimer’s disease and diabetes, where nerve cell death also occurs in the retina. The immediate challenge is manufacturing the dye under strict quality standards and securing regulatory approval from the UK’s Medicines and Healthcare products Regulatory Agency.