title: Validity and reliability of the MTI photoscreener.
abstract: OBJECTIVE
  The prevalence and necessity for early detection of vision problems illustrate the need for improved methods of vision screening in preschool children. This study assessed the validity and reliability of a new device, the MTI photoscreener in a cross-sectional field study.
  
  
  METHODS
  An appropriate sample size (> 140) was calculated and recruited for the study. All children (N = 161) in a migrant workers summer education program were screened with the MTI Photoscreener. Simultaneously and in a masked design, disease status was determined by the Modified Clinic Technique, a well established method for diagnosing the conditions which the MTI screener was designed to detect.
  
  
  RESULTS
  Validity measures revealed a sensitivity of 54%, specificity of 87%, phi coefficient of 0.40, and positive predictive value of 52%. Repeatability was assessed by the kappa coefficient, by a test for effect modification by examiner, and by comparison of sensitivity and specificity across 12 masked examiners. The kappa coefficient was 0.38. A test for effect modification suggested that differences existed among the examiners. Variability of sensitivity was high, but variability of specificity was low.
  
  
  CONCLUSIONS
  Methods for vision screening in preschool children are limited. The MTI Photoscreener is an easy and efficient method, but the validity and reliability is a concern. Comparison of our results with other studies suggests future potential for this instrument provided protocols are refined and further field studies reveal efficacy.
authors.affiliation: New England College of Optometry, Boston, Massachusetts, USA.
authors.forename: S
authors.initials: S
authors.lastname: Hatch
authors.forename: C D
authors.initials: CD
authors.lastname: Tibbles
authors.forename: I R
authors.initials: IR
authors.lastname: Mestito
authors.forename: R
authors.initials: R
authors.lastname: Read
authors.forename: L
authors.initials: L
authors.lastname: Traveis
authors.forename: J
authors.initials: J
authors.lastname: Richman
mesh_terms: D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005189:False Positive Reactions; D006801:Humans; D011237:Predictive Value of Tests; D012030:Refractive Errors / Q000175:diagnosis*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014171:Transients and Migrants; D014786:Vision Disorders / Q000175:diagnosis*; D015351:Vision Screening / Q000295:instrumentation*