title: Developments in contact lens measurement: A comparative study of industry standard geometric inspection and optical coherence tomography.
abstract: OBJECTIVE
  The aim of this study was to compare a developmental optical coherence tomography (OCT) based contact lens inspection instrument to a widely used geometric inspection instrument (Optimec JCF), to establish the capability of a market focused OCT system.
  
  
  METHODS
  Measurements of 27 soft spherical contact lenses were made using the Optimec JCF and a new OCT based instrument, the Optimec is830. Twelve of the lenses analysed were specially commissioned from a traditional hydrogel (Contamac GM Advance 49%) and 12 from a silicone hydrogel (Contamac Definitive 65), each set with a range of back optic zone radius (BOZR) and centre thickness (CT) values. Three commercial lenses were also measured; CooperVision MyDay (Stenfilcon A) in -10D, -3D and +6D powers. Two measurements of BOZR, CT and total diameter were made for each lens in temperature controlled saline on both instruments.
  
  
  RESULTS
  The results showed that the is830 and JCF measurements were comparable, but that the is830 had a better repeatability coefficient for BOZR (0.065mm compared to 0.151mm) and CT (0.008mm compared to 0.027mm). Both instruments had similar results for total diameter (0.041mm compared to 0.044mm).
  
  
  CONCLUSIONS
  The OCT based instrument assessed in this study is able to match and improve on the JCF instrument for the measurement of total diameter, back optic zone radius and centre thickness for soft contact lenses in temperature controlled saline.
authors.affiliation: Aston University, Life and Health Sciences, Biomedical Engineering, Birmingham, United Kingdom; Optimec Limited, Malvern, United Kingdom. Electronic address: b.coldrick1@aston.ac.uk.
authors.forename: Benjamin J
authors.initials: BJ
authors.lastname: Coldrick
authors.affiliation: Optimec Limited, Malvern, United Kingdom.
authors.forename: Colin
authors.initials: C
authors.lastname: Richards
authors.affiliation: Aston University, Engineering and Applied Sciences, AIPT, Birmingham, United Kingdom.
authors.forename: Kate
authors.initials: K
authors.lastname: Sugden
authors.affiliation: Aston University, Life and Health Sciences, Biomedical Engineering, Birmingham, United Kingdom.
authors.forename: James S
authors.initials: JS
authors.lastname: Wolffsohn
authors.affiliation: Aston University, Life and Health Sciences, Biomedical Engineering, Birmingham, United Kingdom.
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Drew
mesh_terms: D003261:Contact Lenses / Q000592:standards*; D004867:Equipment Design; D019544:Equipment Failure Analysis / Q000295:instrumentation* / Q000592:standards*; D019981:Health Care Sector / Q000592:standards; D038622:Internationality; D009885:Ophthalmology / Q000295:instrumentation / Q000592:standards; D017410:Practice Guidelines as Topic; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D041623:Tomography, Optical Coherence / Q000295:instrumentation* / Q000592:standards*