Augmented reality display with waveguide configured to capture images of eye and/or environment

A head mounted display system configured to project light to an eye of a user to display augmented reality image content in a vision field of the user, the head mounted display system comprising:

• a frame configured to be supported on a head of the user;
• an image projector coupled to the frame and configured to project images into the user's eye to display image content in the vision field of the user;
• a camera coupled to the frame;
• a waveguide coupled to the frame and optically coupled to the camera;
• an optical coupling optical element coupled to the frame and configured such that light is coupled into the waveguide;
• an out-coupling element coupled to the frame and configured to direct light emitted from the waveguide to the camera;
• a first light source coupled to the frame and configured to direct light to the user's eye;
• and
• electronics coupled to the first light source and to the camera, the electronics configured to control the camera to capture images periodically.