Treating blindnessCredit: Brown Bird DesignOptogenetics offers a flexible approach to treating, and possibly curing, blindness. The retina’s photoreceptor cells use light-sensitive proteins, called opsins, to convert light entering the eye into electrical signals. In a 2011 study, the team engineered cells to respond to blue light by expressing a protein known to modulate blood glucose. In 2017 Fussenegger and his colleagues described implanting wirelessly powered LEDs along with the engineered cells to create a smartphone-controlled semiautomatic system. Controlling gut microbesCredit: Brown Bird DesignThe gut microbiome is immensely complex and includes trillions of individual microbes, most of whose functions are not understood.