1. A head mounted display system configured to project variable levels of blue light to an eye of a user, the display system comprising: a frame configured to be wearable on the head of the user; a display configured to project at least blue light into the eye of the user and to modify an intensity of the blue light relative to an intensity of non-blue light; a camera configured to capture a first image of the eye while the display projects light at a first ratio of intensity of blue light to non-blue light into the eye and configured to capture a second image of the eye while the display projects a second ratio of intensity of blue light to non-blue light different from the first ratio into the eye; and a hardware processor programmed to: analyze an image from the camera to determine a change in a pupil parameter between the reference image and the survey image passes a biometric application threshold; based at least in part on the determined change, instruct the display to modify a ratio of the intensity of blue light to non-blue light; determine that the change in the pupil parameter between the second image and the first image matches a biometric characteristic of a human individual; and determine an identity of the human individual.