title: Does "Touching Four" on the Worth 4-dot test indicate fusion in young children? A computer simulation.
abstract: OBJECTIVE
  "Touching four" dots on the Worth 4-dot test is used sometimes as an indication of fusion in young children. The authors examined the reliability of this test.
  
  
  METHODS
  A computer simulation of the Worth 4-dot test generated images representing fusion, suppression, and alternate fixation. Sixteen children, ranging in age from 32 to 48 months, were examined using this test.
  
  
  RESULTS
  None of the children could accurately describe the images verbally. Alternate fixation could not be distinguished from fusion by asking the subjects to touch the dots. Monocular suppression was identified accurately in all subjects.
  
  
  CONCLUSIONS
  Touching four dots on the Worth 4-dot test does not distinguish fusion from alternate fixation in children with normal ocular alignment. This has important implications regarding the diagnosis of monofixation syndrome and assessment of the response to a prism adaptation trial in young children.
authors.affiliation: Department of Ophthalmology and Visual Sciences, Washington University Medical Center, St. Louis, MO 63110, USA.
authors.forename: G T
authors.initials: GT
authors.lastname: Lueder
authors.forename: K
authors.initials: K
authors.lastname: Arnoldi
mesh_terms: D000221:Adaptation, Ocular; D002675:Child, Preschool; D003198:Computer Simulation; D005403:Fixation, Ocular / Q000502:physiology; D006801:Humans; D010364:Pattern Recognition, Visual / Q000502:physiology; D010468:Perceptual Disorders / Q000175:diagnosis; D015203:Reproducibility of Results; D013285:Strabismus / Q000175:diagnosis; D015357:Vision Disparity / Q000502:physiology; D014787:Vision Tests / Q000379:methods*; D015348:Vision, Binocular / Q000502:physiology*