<prompt> Illuminated frenzel glasses are used in detecting-NystagmusHeterophoriaEsotropiaAstigmatism  <response>: Frenzel goggles are a diagnostic tool used in ophthalmology, otolaryngology and audiovestibular medicine for the medical evaluation of involuntary eye movement nystagmus. They are named after Frenzel, a German physician Ref AK khurana 6e p515 