title: Corneal thickness at different reference points from Orbscan II system.
abstract: BACKGROUND
  To locate the thinnest region of the cornea and ascertain whether there is a mismatch between the corneal apex and the thinnest part of the cornea, both as defined by the Orbscan II system.
  
  
  METHODS
  Ninety-two eyes of 46 normal subjects were investigated with three reference points identified: the fixation point, the corneal apex and the thinnest region of the cornea. These three points were predetermined by the topographic software system and categorised into different quadrants.
  
  
  RESULTS
  The thinnest region of the cornea was found to be located in the inferior temporal quadrant for the right eye and inferior for the left eye. There was no significant difference in corneal thickness between the thinnest region of the cornea and the corneal apex. There was a significant difference found in the location of the reference points (p < 0.01).
  
  
  CONCLUSIONS
  Differences in the location of the reference points may be of clinical significance, however, our study showed that the corneal thickness at these reference points is not significantly different. Users of the Orbscan II system are free to use any reference points at the central region without reaching any significant difference in corneal thickness.
authors.affiliation: Department of Optometry and Radiography, The Hong Kong Polytechnic University, Kowloon, Hong Kong SAR, China.
authors.forename: Andrew K C
authors.initials: AK
authors.lastname: Lam
authors.forename: Judy S
authors.initials: JS
authors.lastname: Chan
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D019781:Corneal Topography; D003936:Diagnosis, Computer-Assisted; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012016:Reference Values