title: Automated measurement of resolution acuity in infants using remote eye-tracking.
abstract: OBJECTIVE
  To validate a novel, automated test of infant resolution acuity based on remote eye-tracking.
  
  
  METHODS
  Infants aged 2 to 12 months were tested binocularly using a new adaptive computerized test of infant vision using eye tracking (ACTIVE), and Keeler infant acuity cards (KIAC). The ACTIVE test ran automatically, using remote eye-tracking to assess whether the infant fixated a black-and-white grating of variable spatial frequency. Test-retest reliability was assessed by performing each test twice. Accuracy was assessed by comparing acuity measures across tests and with established age-norms, and by comparing low-contrast acuity estimates in adults with data reported previously.
  
  
  RESULTS
  All infants completed the ACTIVE test at least once. Median test duration was 101 seconds. Measured visual acuity increased with age (P < 0.001), and 90% of mean acuity estimates were within previously published 90% tolerance limits (based on acuity-card age norms). Acuity estimates were also correlated, within-subjects, with results from the KIAC (P = 0.004). In terms of reliability, 86% of acuity estimates deviated by ≤1 octave, with no significant difference in test-retest reliability between the ACTIVE and KIAC procedures (P = 0.461). In adults, acuity estimates from the ACTIVE test did not differ significantly from values reported by previous authors (P > 0.183).
  
  
  CONCLUSIONS
  An adaptive computerized test of infant vision using eye-tracking provides a rapid, automated measure of resolution acuity in preverbal infants. The ACTIVE performed comparably to the current clinical gold standard (acuity cards) in terms of testability, reliability, and accuracy, and its principles can be extended to measure other visual functions.
authors.affiliation: Institute of Ophthalmology, University College London (UCL), United Kingdom.
authors.forename: Pete R
authors.initials: PR
authors.lastname: Jones
authors.affiliation: Institute of Ophthalmology, University College London (UCL), United Kingdom.
authors.forename: Sarah
authors.initials: S
authors.lastname: Kalwarowsky
authors.affiliation: Department of Developmental Science, University College London (UCL), United Kingdom Department of Experimental Psychology, University of Oxford, United Kingdom.
authors.forename: Janette
authors.initials: J
authors.lastname: Atkinson
authors.affiliation: Department of Experimental Psychology, University of Oxford, United Kingdom.
authors.forename: Oliver J
authors.initials: OJ
authors.lastname: Braddick
authors.affiliation: Institute of Ophthalmology, University College London (UCL), United Kingdom Department of Psychology, Durham University, United Kingdom.
authors.forename: Marko
authors.initials: M
authors.lastname: Nardini
mesh_terms: D016022:Case-Control Studies; D003936:Diagnosis, Computer-Assisted / Q000379:methods; D005133:Eye Movements; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D015203:Reproducibility of Results; D014786:Vision Disorders / Q000175:diagnosis*; D014787:Vision Tests / Q000295:instrumentation / Q000379:methods*; D015348:Vision, Binocular / Q000502:physiology; D014792:Visual Acuity
keywords: eye-tracking; infant vision; visual acuity