Illuminated frenzel glasses are used in detecting-
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 6/e p515
Nystagmus
Heterophoria
Esotropia
Astigmatism
Neuro-ophthalmology