title: Rate of Strabismus Detection on Digital Photographs Increases by Using Off-center Near Target.
abstract: OBJECTIVE
  To increase the detection rate of strabismus on digital photographs, with the ultimate aim of developing a new automated strabismus detection algorithm.
  
  
  METHODS
  In this prospective case series, the authors acquired digital face photographs of 409 children with manifest or latent strabismus, using a 14-million-pixel camera with CCD image sensor. Of the last 52 enrolled, 34 image sets were selected for this study: 29 with manifest and 5 with latent strabismus. Images were taken at a distance of 40 to 70 cm in primary position, with the camera lens as the fixation target and in slight off-center fixation, and using a novel target of small light-emitting diodes mounted onto the camera case. The location of the corneal light reflection was manually calculated in relation to the center of the pupil in both eyes and ocular deviation as the difference in corneal light reflection location between the two eyes. In orthotropia, the expected deviation is zero.
  
  
  RESULTS
  In children with phorias, the mean corneal light reflection location difference between the eyes was -0.10 ± 0.14 mm in primary position and -2.02 ± 0.39 mm in off-center fixation. Using a threshold of ±0.5 mm on either side of zero for central and of 2 mm for off-center fixation, sensitivity to detect strabismus increased from 65.6% in central to 79.3% in off-center fixation, respectively. The calculation of specificity will require inclusion of a population of individuals without strabismus.
  
  
  CONCLUSIONS
  Off-center fixation onto a near target ensures that participants are actively looking at the target and may increase accommodative effort, thereby increasing the detection rate of strabismus. [J Pediatr Ophthalmol Strabismus. 2017;54(2):90-96.].
authors.forename: Ron
authors.initials: R
authors.lastname: Maor
authors.forename: Joanna
authors.initials: J
authors.lastname: Holland
authors.forename: Vijay
authors.initials: V
authors.lastname: Tailor
authors.forename: Marina
authors.initials: M
authors.lastname: Banteka
authors.forename: Payal
authors.initials: P
authors.lastname: Khandelwal
authors.forename: Selina
authors.initials: S
authors.lastname: Glaze
authors.forename: Simon
authors.initials: S
authors.lastname: Barnard
authors.forename: Yuval
authors.initials: Y
authors.lastname: Yashiv
authors.forename: Annegret H
authors.initials: AH
authors.lastname: Dahlmann-Noor
mesh_terms: D002648:Child; D005260:Female; D005403:Fixation, Ocular; D006801:Humans; D008297:Male; D010781:Photography / Q000295:instrumentation*; D011446:Prospective Studies; D011680:Pupil; D015203:Reproducibility of Results; D013285:Strabismus / Q000175:diagnosis*