DO FRENZEL GLASSES HAVE A PLACE IN THE MODERN ELECTRONYSTAGMOGRAPHY LABORATORY

Electronystagmography (ENG) is generally performed with the patient's eyes closed to prevent visual fixation. In this way, direct observatio n of eye movements is impossible. By means of Frenzel glasses (FG), th e direct observation of eye movements is possible, but the effectivene ss of visual fixation suppression and the diagnostic contribution of F G must still be studied. One hundred seven patients with vertigo parti cipated in this study. Each patient underwent a complete ENG test unde r two fixation modalities: (a) closed eyes and (b) open eyes with FG. The spontaneous nystagmus and the Hallpike test did not show any signi ficant difference between the two fixation modalities. The slow-phase velocity of nystagmus with the caloric test was significantly greater with closed eyes, but the pattern of nystagmus with FC fixation was mo re tooth-shaped and regular than that with closed eyes. It is conclude d that using FG when performing an ENG may improve its diagnostic valu e.