1. A head mounted display system configured to provide 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 the images from the camera to determine whether a change in a pupil parameter between the second image and the first 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 and instruct the camera to capture a third imam of the eye; determine that a change in the pupil parameter between the third image and the first image or the second image passes a biometric application threshold; and perform a biometric application in response to the determination that the change in the pupil parameter between the third image and the first image or the second image passes a biometric application threshold.