Researchers have discovered that children who have to wear an eye patch to treat the condition known as lazy eye are more likely to be bullied by other children as they go through school.
But if the test is conducted at a younger age - and if the patching treatment is completed by the time they start school - the children are less likely to be victims of the bullies.
The results come from an examination of 4,400 children who part of the Children of the 90s study based at the University of Bristol.
Bristol eye surgeon Cathy Williams set out to investigate the implications of the age of screening and treatment, for children who had suffered the condition amblyopia (also known as lazy eye). Although it affects 3 per cent of children, it is simply treated with an eye patch, worn over the stronger eye.
Controversially, pre-school screening for amblyopia at the age of three has been abandoned in much of the UK on the grounds that all children can be checked more effectively at school age. It is said that the age at starting treatment is irrelevant.
Under current guidelines, children should be tested by the school nurse, at the age of 4 or 5.
Dr Williams says: "One argument for preschool screening is that patching treatment is more likely to have concluded before school starts, so avoiding adverse reactions from other children.
"We decided to test this by comparing two groups of children: those who had been offered preschool screening at the age of 3 and the others that hadn't."
At the age of 8, all the children were asked whether they had been bullied - physically or emotionally.
Dr Williams says: "In the group who had been offered preschool screening, there was an almost 50 per cent reduction in the proportion of children (who had been treated for amblyopia) who reported having been bullied.
"Whilst the causes of bullying are complex and linked to many factors, these data do suggest that the timing of intervention to detect amblyopia may lessen the likelihood of a child who is treated with patching being bullied.
"Both parents and children might consider that halving the risk of being bullied is a good reason for a child to attend a preschool vision screening appointment, rather than wait for detection and treatment at school age... especially since we know that repeated bullying is consistently associated with physical and emotional problems for the victims and may have long-term consequences.
"Reducing the need for patching treatment in school could be one way to avoid it.”
Academic paper reference:
Williams C, Horwood J, Northstone K, Herrick D, Waylen A, Wolke D, ALSPAC Study Group. The timing of patching treatment and a child's wellbeing. British Journal of Ophthalmology. doi:10.1136/bjo.2006.091082
Notes:
1. Amblyopia is a condition that affects 3 per cent of children and is normally treated with an eye patch. If it goes untreated until age 7 or 8, the sight in the weaker eye may never improve.
2. Since a report in 1997 from the NHS Centre for Reviews and Dissemination at the University of York found that there was no evidence that early treatment worked better than treatment at school age, in some areas tests for pre-school children have been discontinued. This has caused widespread debate and disagreement between professionals and highlighted the need for more research
3. An earlier study by the ALSPAC team (published in June 2002) found that children with amblyopia have a much better chance of becoming cured if treatment starts before three years old,
4. ALSPAC The Avon Longitudinal Study of Parents and Children (also known as Children of the 90s) is a unique ongoing research project based in the University of Bristol. It enrolled 14,000 mothers during pregnancy in 1991-2 and has followed most of the children and parents in minute detail ever since.
5. The ALSPAC study could not have been undertaken without the continuing financial support of the Medical Research Council, the Wellcome Trust, and the University of Bristol among many others.