Augmented and virtual reality display systems and methods for determining optical prescriptions by imaging retina

A wearable augmented reality device comprising:

• an augmented reality head-mounted ophthalmic system comprising:
• an augmented reality display platform configured to pass light from the world into an eye of a wearer wearing the head-mounted system, the eye having a retina, the display platform comprising:
• a fiber scanning display configured to direct light into the eye to form an image;
• and
• an imaging system configured to image the eye,
• wherein the augmented reality head-mounted ophthalmic system is configured to:
• capture first images of the retina with the imaging system;
• and
• determine when one or more second images formed by the fiber scanning display is on the retina to determine an optical prescription of the wearer.