title: Hertel curve: orbital volume increment and proptosis in a cadaver model.
abstract: OBJECTIVE
  This study examined the relation between effective orbital volume increment and proptosis induced by an inflatable orbital implant in a human cadaver orbit.
  
  
  METHODS
  A 25-ml inflatable latex balloon was inserted between the periorbita and orbital floor in 15 human cadavers. Hertel measurements were taken for each milliliter over a total 7-ml volume increment. Five trials per orbit for 15 cadavers resulted in 525 data points.
  
  
  RESULTS
  Average exophthalmos per milliliter of volume increment was plotted over 7 ml, using 1-ml volume increments. The resultant curve, which was termed a Hertel curve, was linear over 7 ml (R > 99%) and had a slope of 0.62 mm per milliliter of volume increment.
  
  
  CONCLUSIONS
  An inflatable orbital implant is an effective tool for introducing a specified amount of volume in the cadaver orbit. The predictable relation between proptosis and volume increment (Hertel curve) may be a useful tool for surgeons in planning the size of an implant required to surgically correct enophthalmos.
authors.affiliation: Doheny Eye Institute, Keck School of Medicine, University of Southern California, Los Angeles, California, USA.
authors.forename: Timothy B
authors.initials: TB
authors.lastname: Neuschwander
authors.forename: Eli L
authors.initials: EL
authors.lastname: Chang
authors.forename: Alfredo A
authors.initials: AA
authors.lastname: Sadun
mesh_terms: D001763:Blepharoptosis / Q000209:etiology / Q000473:pathology*; D002102:Cadaver; D005260:Female; D006801:Humans; D008297:Male; D008953:Models, Anatomic; D009915:Orbit / Q000473:pathology*; D020273:Orbital Implants / Q000009:adverse effects*