title: Assessment of multifocal contact lens over-refraction using an infrared, open-field autorefractor: A preliminary study.
abstract: OBJECTIVE
  To evaluate the usefulness of an infrared open-field autorefractor as a predictor of the refractive error when fitting multifocal contact lenses (MCL).
  
  
  METHODS
  Objective and subjective measurements of the non-cycloplegic distance refractive error were compared in patients wearing MCL. We used the Grand Seiko WAM-5500 autorefractor for the objective measurements. Three commercially available MCL were tested. Twenty-one eyes of sixteen healthy adults were included in the study. Over-refraction was evaluated in terms of spherical equivalent (SE) and astigmatic vectors (J0 and J45). The mean difference±SD of each parameter was calculated. The Kolmogorov-Smirnov test was used to verify the normal distribution. Pearson's correlation, Bland and Altman plot and paired sample t test were used to compare the results obtained with both methods.
  
  
  RESULTS
  The mean difference between objective and subjective results of the SE over-refraction was 0.13±0.42D; for astigmatic vectors J0 and J45 were 0.03±0.32D and -0.00±0.17D, respectively. The Kolmogorov-Smirnov test showed a normal distribution for all parameters. The highest Pearson's correlation coefficients were obtained for the SE with values of 0.98 without MCL and 0.97 with MCL. The lowest were obtained for J45 with values of 0.65 without MCL and 0.75 with MCL. Significant correlations were obtained for each parameter. The paired sample t test failed to show significant differences in analyzed parameters except for J0 without MCL.
  
  
  CONCLUSIONS
  The Grand Seiko WAM-5500 can be used as a screening method of over-refraction in the clinical fitting of MCL.
authors.affiliation: Centre for Sensors, Instruments and Systems Development (CD6), Universitat Politècnica de Catalunya (UPC), Spain. Electronic address: anna.giner-tort@cd6.upc.edu.
authors.forename: Anna
authors.initials: A
authors.lastname: Giner
authors.affiliation: Centre for Sensors, Instruments and Systems Development (CD6), Universitat Politècnica de Catalunya (UPC), Spain.
authors.forename: Mikel
authors.initials: M
authors.lastname: Aldaba
authors.affiliation: Centre for Sensors, Instruments and Systems Development (CD6), Universitat Politècnica de Catalunya (UPC), Spain.
authors.forename: Montserrat
authors.initials: M
authors.lastname: Arjona
authors.affiliation: Centre for Sensors, Instruments and Systems Development (CD6), Universitat Politècnica de Catalunya (UPC), Spain.
authors.forename: Meritxell
authors.initials: M
authors.lastname: Vilaseca
authors.affiliation: Centre for Sensors, Instruments and Systems Development (CD6), Universitat Politècnica de Catalunya (UPC), Spain.
authors.forename: Jaume
authors.initials: J
authors.lastname: Pujol
mesh_terms: D000328:Adult; D003261:Contact Lenses; D004867:Equipment Design; D019544:Equipment Failure Analysis / Q000295:instrumentation; D005260:Female; D006801:Humans; D007259:Infrared Rays; D008027:Light; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D011305:Presbyopia / Q000175:diagnosis* / Q000534:rehabilitation*; D017755:Prosthesis Fitting / Q000379:methods*; D012029:Refraction, Ocular; D012031:Refractometry / Q000295:instrumentation*; D015203:Reproducibility of Results; D012542:Scattering, Radiation; D012680:Sensitivity and Specificity; D016896:Treatment Outcome
keywords: Autorefractor; Multifocal contact lens; Over-refraction; Refractive error; Simultaneous vision