title: The takeaway Frenzel goggles: a Fresnel-based device.
abstract: OBJECTIVE
  To develop and evaluate new thin and light glasses for the examination of patients with nystagmus and to compare them with Frenzel goggles.
  
  
  METHODS
  First, we designed new examination glasses: a Fresnel-based device with a short focal length that is not as heavy or bulky as Frenzel goggles. Second, visual-fixation suppression of postrotatory nystagmus with Frenzel goggles and the Fresnel-based device, the latter with 2 different magnifications (2- and 4-fold), was compared in 13 healthy subjects. Third, the intensity of the peripheral vestibular spontaneous nystagmus-in 6 patients with acute vestibular neuritis-with the Frenzel goggles and the Fresnel-based device with the 4-fold magnification was compared. Fourth, the visibility and clinical applicability were evaluated.
  
  
  RESULTS
  The Fresnel-based device weighs 6 g (dimensions 12 × 8 × 0.3 cm). There was no significant difference in the intensity of postrotatory nystagmus between the Fresnel-based device with 4-fold magnification (37.3 ± 17.9°/s) and the Frenzel goggles (39.0 ± 18.3°/s). There was also no significant difference between the intensity of peripheral vestibular spontaneous nystagmus in the patients with acute vestibular neuritis. The Fresnel-based device can be easily applied.
  
  
  CONCLUSIONS
  For suppression of nystagmus, the new Fresnel-based device or so-called M glasses is not inferior to Frenzel goggles. Doctors can carry it in their pocket, it is inexpensive, and easy to handle and to fix to the patient's nose so that it can be used in daily practice for the bedside examination.
  
  
  METHODS
  This study provides Class III evidence that, in subjects with nystagmus, a Fresnel-based device identifies a similar intensity of nystagmus as that identified by Frenzel goggles.
authors.affiliation: From the German Center for Vertigo and Balance Disorders (M.S., C.F., L.H., O.B.), Department of Neurology (M.S.), and Institute of Biometrics and Epidemiology (O.B.), University Hospital, Munich, Germany. Michael.Strupp@med.uni-muenchen.de.
authors.forename: Michael
authors.initials: M
authors.lastname: Strupp
authors.affiliation: From the German Center for Vertigo and Balance Disorders (M.S., C.F., L.H., O.B.), Department of Neurology (M.S.), and Institute of Biometrics and Epidemiology (O.B.), University Hospital, Munich, Germany.
authors.forename: Carolin
authors.initials: C
authors.lastname: Fischer
authors.affiliation: From the German Center for Vertigo and Balance Disorders (M.S., C.F., L.H., O.B.), Department of Neurology (M.S.), and Institute of Biometrics and Epidemiology (O.B.), University Hospital, Munich, Germany.
authors.forename: Lena
authors.initials: L
authors.lastname: Hanß
authors.affiliation: From the German Center for Vertigo and Balance Disorders (M.S., C.F., L.H., O.B.), Department of Neurology (M.S.), and Institute of Biometrics and Epidemiology (O.B.), University Hospital, Munich, Germany.
authors.forename: Otmar
authors.initials: O
authors.lastname: Bayer
mesh_terms: D000328:Adult; D004867:Equipment Design; D005260:Female; D006801:Humans; D007909:Lenses / Q000191:economics; D008297:Male; D008875:Middle Aged; D009759:Nystagmus, Pathologic / Q000175:diagnosis* / Q000209:etiology; D009760:Nystagmus, Physiologic; D010808:Physical Examination / Q000295:instrumentation; D010812:Physical Stimulation; D012399:Rotation; D020338:Vestibular Neuronitis / Q000150:complications