The Kansas Supreme Court has held that the horizontal gaze nystagmus test (HGN) is not admissible. It was ruled not scientifically reliable. This is a test many law enforcement have driver’s perform that checks your eyes for tracking. It is junk science. The Kansas Supreme Court agrees.
https://www.kscourts.org/KSCourts/media/KsCourts/Opinions/104940.pdf?ext=.pdf