title: "Pillar and collar" technique for measuring the axial edge lift of multicurve rigid lenses.
abstract: BACKGROUND
  The method of using an optical spherometer and a lens thickness gauge, in combination with a pillar and collar, has previously been shown to be repeatable and accurate (to 0.01 mm) in measuring the edge lift of rigid monocurve lenses.
  
  
  OBJECTIVE
  This paper goes on to validate the technique for measurements taken on edge-finished multicurve rigid lenses.
  
  
  METHODS
  The axial edge lift (AEL) of a series of multicurve rigid lenses having known values of AEL was measured using an optical spherometer, a thickness gauge, and contact lens V gauge in a similar way as was described in the companion paper.
  
  
  RESULTS
  The results show that as long as a correction factor of 0.01 mm is applied, as found in the previous paper, the technique will allow satisfactory verification of the edge lift.
  
  
  CONCLUSIONS
  The technique is accurate and reproducible, even in multicurve lens designs, provided that a calibrating correction factor of 0.01 mm is applied to account for methodological error. It will also indirectly allow the accuracy of manufacture of the peripheral curves and diameters of any rigid contact lens to be verified.
authors.affiliation: Department of Optometry, University of Bradford, West Yorkshire, United Kingdom.
authors.forename: W A
authors.initials: WA
authors.lastname: Douthwaite
authors.forename: M A
authors.initials: MA
authors.lastname: Hurst
mesh_terms: D003261:Contact Lenses / Q000592:standards; D003315:Cornea / Q000033:anatomy & histology; D006801:Humans; D019904:Polymethyl Methacrylate; D011474:Prosthesis Design; D017755:Prosthesis Fitting; D015203:Reproducibility of Results
chemical_list: D019904:Polymethyl Methacrylate