title: Parallax-free exophthalmometry: a comprehensive review of the literature on clinical exophthalmometry and the introduction of the first parallax-free exophthalmometer.
abstract: OBJECTIVE
  To present the first parallax-free exophthalmometer design.
  
  
  BACKGROUND
  Exophthalmometry is an important clinical tool. We provide a historic overview of clinical exophthalmometer designs, and we review current problems encountered in exophthalmometry.
  
  
  METHODS
  We present a new and parallax-free exophthalmometer design that we have evaluated in 49 patients visiting our orbital clinic.
  
  
  RESULTS
  The mean age of the patients was 49.8 years and 72% were female. The Pearson interobserver variation was 0.97, and 94% of the Hertel values measured by the two observers were within the limits (1.6 mm) of agreement.
  
  
  CONCLUSIONS
  This meter appears to be a reliable instrument for exophthalmometry. It is the first instrument that allows for a complete parallax-free measurement.
authors.affiliation: Orbital Center, Department of Ophthalmology, Academic Medical Center, University of Amsterdam , Amsterdam , The Netherlands , and.
authors.forename: Stijn W
authors.initials: SW
authors.lastname: Genders
authors.forename: Daphne L
authors.initials: DL
authors.lastname: Mourits
authors.forename: Mohammad
authors.initials: M
authors.lastname: Jasem
authors.forename: Roel J H M
authors.initials: RJ
authors.lastname: Kloos
authors.forename: Peerooz
authors.initials: P
authors.lastname: Saeed
authors.forename: Maarten Ph
authors.initials: MP
authors.lastname: Mourits
mesh_terms: D003941:Diagnostic Techniques, Ophthalmological / Q000266:history / Q000295:instrumentation*; D004867:Equipment Design; D005094:Exophthalmos / Q000175:diagnosis* / Q000266:history; D049672:History, 19th Century; D049673:History, 20th Century; D049674:History, 21st Century; D006801:Humans
keywords: Exophthalmometer; exophthalmometry; exophthalmos; parallax error; proptosis