title: Calibration and validation of the 2WIN photoscreener compared to the PlusoptiX S12 and the SPOT.
abstract: OBJECTIVE
  Pediatricians are interested in the amblyopia detection ability of photoscreeners, whereas ophthalmologists ponder their value as autorefractors. The 2WIN (Adaptica, Padova, Italy) is a new device capable of estimating refractive error and ocular alignment by infrared photoscreening.
  
  
  METHODS
  Sequential pediatric eye patients with a high (56% to 60%) prescreening prevalence of amblyopia risk factors were screened with the PlusoptiX S12 (PlusoptiX, Inc., Atlanta, GA), SPOT (PediaVision, Lake Mary, FL), and 2WIN photoscreeners before confirmatory examination adhering to American Association for Pediatric Ophthalmology and Strabismus guidelines and Alaska Blind Child Discovery institutional review board protocol. Instrument referral guidelines determined through phase 1 comparison was then applied on additional patients for validation in phase 2.
  
  
  RESULTS
  Sixty-two children (age: 1 to 10 years, mean: 5.2 years) were screened with all three devices before cycloplegic examination. Refractive results were inconclusive due to pupil size, cooperation, and out-of-range values. Values for sensitivity (91% and 78%), specificity (71% and 59%), and inconclusive rate (10% and 13%) were found for PlusoptiX and SPOT. The 2WIN was calibrated for this age range (phase 1), yielding 71% sensitivity, 67% specificity, and a 5% inconclusive rate. Regression compared to examination for the PlusoptiX, SPOT, and 2WIN, respectively, were sphere (r(2): 0.76, 0.87, and 0.58), cylinder power (r(2): 0.67, 0.56, and 0.50), and cylinder axis (r(2): 0.71, 0.41, and 0.40). A preferred 2WIN instrument criteria set was determined from the receiver operating characteristic curve. In phase 2, with 117 patients comparing 2WIN to PlusoptiX A-09, sensitivity was 73% and 85%, specificity was 76% and 73%, and inconclusive rate was 8% and 12%, respectively. The three instant-interpreting photorefractors performed well on amblyopic children, with the 2WIN having low inconclusive results. The PlusoptiX outperformed the SPOT and 2WIN as an autorefractor, particularly with respect to astigmatism power and axis.
  
  
  CONCLUSIONS
  The new 2WIN is a promising addition to portable photoscreeners for amblyopia detection and estimating refractive error.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Kirk
authors.forename: M Diane
authors.initials: MD
authors.lastname: Armitage
authors.forename: Shelley
authors.initials: S
authors.lastname: Dunn
authors.forename: Robert W
authors.initials: RW
authors.lastname: Arnold
mesh_terms: D000550:Amblyopia / Q000175:diagnosis*; D002138:Calibration; D002648:Child; D002675:Child, Preschool; D004867:Equipment Design; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D012372:ROC Curve; D012029:Refraction, Ocular / Q000502:physiology; D012030:Refractive Errors / Q000175:diagnosis*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D015351:Vision Screening / Q000295:instrumentation*; D015348:Vision, Binocular / Q000502:physiology