Eye-tracking is used to measure how long you look directly at the light.
Through the small camera installed on the device, your face is photographed, and a small program assesses whether you are looking directly in the direction of the light. That information is saved, but the image is deleted immediately. This process is repeated throughout the whole light stimulation session.
This number is used by the researchers in the clinical studies, as it is assumed to be of great importance of how effectively the subjects look at the light. If you are not in a clinical trial, the data won’t be collected and the information will not be used for anything.
Eye-tracking does NOT collect personal information or images.