Retinal disorders, including age-related macular degeneration, are leading causes of vision loss worldwide. New treatments, such as gene therapies and stem cell regeneration, require therapeutics to be introduced to the subretinal space due to poor diffusion to the active component of the retina. Subretinal injections are a difficult and risky surgical procedure and have been suggested as a candidate for robot-assisted surgery. We propose a different actuation paradigm to existing robotic approaches using remote magnetic navigation to control a flexible microcannula. A flexible cannula allows for high dexterity and considerable safety advantages over rigid tools, while maintaining the benefits of micrometer precision, hand tremor removal, and telemanipulation. The position of the cannula is tracked in real-time using near-infrared tip illumination, allowing for semi-automatic placement of the cannula and an intuitive user interface. Using this tool, we successfully performed several subretinal injections in ex-vivo porcine eyes under both microscope and optical coherence tomography visualization.