Effectiveness of routine population-wide orthoptic preschool vision screening tests at age 6-24 months in the Netherlands.

Purpose: The effectiveness of preverbal orthoptic tests at age 6, 9, 14 and 24 months in population-wide screening was assessed.

Methods: Two consecutive birth cohorts at 134 centres were compared. At general health screening visits, children born July-December 2011 were vision screened four times between 6 and 24 months with inspection, pupillary reflexes, eye motility, Hirschberg, cover test and monocular pursuit.