While replacing a non-functioning eye with a functioning bionic eye is not yet possible as of 2014, a device called Argus II has successfully restored partial sight to some completely blind individuals. The system uses a digital camera to send signals to electrodes planted onto the patient's retina.
The camera is mounted on a pair of glasses, and is similar to the cameras that are used in smart phones. Images from the camera are transmitted to a small device that converts the images into signals the brain can read. The device allows the patient to tell light from dark and discern vague shapes. Because it relies on the brain's ability to interpret such patterns of light and dark as images, it is only effective in diseases where the eye's retina and nervous system are intact, such as retinitis pigmentosa.