Overview
Dr Horwood’s team has found that 4 in 10 children with normal eyesight focus on at the wrong distance for seeing close work clearly at age 5-9. It seems like they may be putting-up with blurred near vision. Children with developmental problems or who are long-sighted also under-focus.
Clear vision seems likely to be important for children to read, concentrate and pay attention. But screening services concentrate on distance vision and spotting problems such as ‘lazy eye’ (amblyopia) or astigmatism. No previous studies have looked at how well children can focus during long periods of close work so we don’t know for sure how much it matters or if, when and how it should be treated if so.
In this project the team is testing 5-10-year-olds with computer games, large- and small print. The aim is to link the results to other aspects of the children’s vision, their reading, attention and IQ. They’re also developing a shorter set of tests for use with large groups of children of all abilities.
If poor focus for close work is linked to poor reading, attention, or IQ, the team will then do a larger, longer study to find out whether poor focus is actually the cause of these problems. If so, then this test might be able to predictwhich children are at risk and in need of exercises or glasses that may prevent later problems with their progress at school or chances later in life.
-
Results
The researchers found that accommodation (the ability to bring objects into focus) appears to be variable between children and may be influenced by the type of target. Children appear to accommodate only as much as necessary to resolve the target. More demanding tasks such as reading print or performing visual search cause higher accommodative responses than reading letters or simply looking at a picture or cartoon. -
Scientific summary
Ocular accommodation and convergence during close work in primary school children
There is strong circumstantial evidence that poor focus (under-accommodation) for near work, is associated with failure at school. While school-entry screening for poor distance vision is currently recommended, surprisingly little attention has been paid to whether near vision is also clear. Research in Dr Horwood’s laboratory suggests that many hyperopic (long sighted) children suffer more blur for near than distance, and that even children with normal distance vision often under-focus for close work. What is not clear is how common this is, or the degree to which it affects vision and learning.
This PhD enables the study of children’s accommodation, at first in a university setting and then in schools to establish how many children operate with blurred near vision. The student is relating objective measures of accommodation to a range of nearwork tasks and also to other visual measures and cognitive measures including reading ability, IQ and attention. The detailed university studies will be used to develop a shorter battery of portable tests to be used in schools on larger numbers of children with different backgrounds and abilities.
If poor accommodation is associated with poor progress at school in a proportion of children, or testing detects children with poor near vision for close work who have passed current vision screening, (particularly due to hyperopia which is often missed), but would benefit from treatment, these data will form the basis of further research to develop a large scale multi-centre intervention trial and / or improved screening protocols.