Binocular vision and eye alignment

Mark Deacon is a qualified Orthoptist working within the NHS, and is studying part-time for a PhD. Mark is looking in detail at the prevalence and types of squint (eye-turn) in children with Down's syndrome and the ways in which the two eyes work together. Through Mark's study, we have already shown that alternating squints (in which the child can use either eye) are much more common in children with Down's syndrome, whereas most ordinary children who squint have a strong preference for using one eye. We don't yet understand why this difference should arise.

Bifocals, when they are needed to aid focusing, can also help reduce the turn in children with squints, but overall, the type of squint (fully accommodative, partially accommodative or non-accommodative) are similar in children with and without Down's syndrome.