Project Summary About 1.3 million Americans aged 40 and older are legally blind, a majority because of diseases with onset later in life, such as glaucoma and age-related macular degeneration. Second Sight has developed the world's first FDA approved retinal implant, Argus II, intended to restore some functional vision for people suffering from retinitis pigmentosa (RP). In this era of smart devices, generic navigation technology, such as GPS mapping apps for smartphones, can provide directions to help guide a blind user from point A to point B. However, these navigational aids do little to enable blind users to form an egocentric understanding of the surroundings, are not suited to navigation indoors, and do nothing to assist in avoiding obstacles to mobility. The Argus II, on the other hand, provides blind users with a limited visual representation of their surroundings that improves users' ability to orient themselves and traverse obstacles, yet lacks features for high-level navigation and semantic interpretation of the surroundings. The proposed research aims to address these limitations of the Argus II through a synergy of state-of-the-art stimultaneous localization and mapping (SLAM) and object recognition technologies. For the past three years, JHU/APL has collaborated with Second Sight to develop similar advanced vision-based capabilities for the Argus II, including capabilities for object recognition and obstacle detection by stereo vision. This proposal is driven by the hypothesis that navigation for users of retinal prosthetics can be greatly improved by incorporating SLAM and object recognition technology conveying environmental information via a retinal prosthesis and auditory feedback. SLAM enables the visual prosthesis system to construct a map of the user's environment and locate the user within that map. The system then provides object location and navigational cues via appropriate sensory modalities enabling the user to mentally form an egocentric map of the environment. We propose to develop and test a visual prosthesis system which 1) constructs a map of unfamiliar environments and localizes the user using SLAM technology 2) automatically identifies navigationally-relevant objects and landmarks using object recognition and 3) provides sensory feedback for navigation, obstacle avoidance, and object/landmark identification.