RADAR: A novel fast-screening method for reading difficulties with special focus on dyslexia

PLoS One. 2017 Aug 11;12(8):e0182597. doi: 10.1371/journal.pone.0182597. eCollection 2017.

Abstract

Dyslexia is a developmental learning disorder of single word reading accuracy and/or fluency, with compelling research directed towards understanding the contributions of the visual system. While dyslexia is not an oculomotor disease, readers with dyslexia have shown different eye movements than typically developing students during text reading. Readers with dyslexia exhibit longer and more frequent fixations, shorter saccade lengths, more backward refixations than typical readers. Furthermore, readers with dyslexia are known to have difficulty in reading long words, lower skipping rate of short words, and high gaze duration on many words. It is an open question whether it is possible to harness these distinctive oculomotor scanning patterns observed during reading in order to develop a screening tool that can reliably identify struggling readers, who may be candidates for dyslexia. Here, we introduce a novel, fast, objective, non-invasive method, named Rapid Assessment of Difficulties and Abnormalities in Reading (RADAR) that screens for features associated with the aberrant visual scanning of reading text seen in dyslexia. Eye tracking parameter measurements that are stable under retest and have high discriminative power, as indicated by their ROC (receiver operating characteristic) curves, were obtained during silent text reading. These parameters were combined to derive a total reading score (TRS) that can reliably separate readers with dyslexia from typical readers. We tested TRS in a group of school-age children ranging from 8.5 to 12.5 years of age. TRS achieved 94.2% correct classification of children tested. Specifically, 35 out of 37 control (specificity 94.6%) and 30 out of 32 readers with dyslexia (sensitivity 93.8%) were classified correctly using RADAR, under a circular validation condition (see section Results/Total Reading Score) where the individual evaluated was not included in the test construction group. In conclusion, RADAR is a novel, automated, fast and reliable way to identify children at high risk of dyslexia that is amenable to large-scale screening. Moreover, analysis of eye movement parameters obtained with RADAR during reading will likely be useful for implementing individualized treatment strategies and for monitoring objectively the success of chosen interventions. We envision that it will be possible to use RADAR as a sensitive, objective, and quantitative first pass screen to identify individuals with reading disorders that manifest with abnormal oculomotor reading strategies, like dyslexia.

MeSH terms

  • Adolescent
  • Case-Control Studies
  • Child
  • Comprehension / physiology
  • Dyslexia / diagnosis*
  • Dyslexia / physiopathology
  • Eye Movements*
  • Female
  • Humans
  • Learning / physiology
  • Male
  • Pattern Recognition, Automated / methods*
  • ROC Curve
  • Reading*
  • Research Design

Grant support

The authors received funding from Emmetropia Eye Institute S.A. and from Medotics Ltd. Vassilios Selimis, Theodora Bachourou and Ioannis M. Aslanides are affiliated to Emmetropia Eye Institute S.A. Emmetropia Eye Institute S.A. provided support in the form of salaries for authors VS, TB and IMA, but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors are articulated in the ‘author contributions’ section. Michail Kalaitzakis and Georgios Kaloutsakis are affiliated to Medotics Ltd. Medotics Ltd. provided support in the form of salaries for authors MK and GK, but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors are articulated in the ‘author contributions’ section. Vassilios Andreadakis is affiliated to Optotech Ltd. Optotech Ltd provided support in the form of salary for author VA, but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific role of this author is articulated in the ‘author contributions’ section.