I must point out South Downs Health NHS Trust's child health service follows national guidelines for monitoring children's health, including their vision, during their pre-school years ("If only my son was given an eye test", The Argus, November 5).

Pre-school children are offered assessments at age six weeks by their GP and at eight months, 18 months and three years by their health visitor. Testing vision in children under the age of three is not straightforward and screening tests for this age group are not always reliable.

If any concerns are raised by parents or noted by the health visitor, or there is a family history of squint, the child is referred to an orthoptist at the Sussex Eye Hospital for detailed testing.

All children in local authority schools are offered vision testing at school entry when they can co-operate easily and the results are reliable.

There is controversy about the effectiveness of early treatment for amblyopia.

Unfortunately, the evidence is not clear-cut and current national guidance indicates there is little difference in outcome if treatment is started at age three rather than age five.

It is important to understand that monitoring development in healthy young children is a partnership between parents, GPs and health visitors.

Information from parents is an important part of this process. Specific screening tests are not infallible.

If parents have any concerns about aspects of their child's development, including vision, they should discuss these with their GP or health visitor.

-Dr Sian Bennett, Clinical Director, Child Health, South Downs Health NHS Trust, Brighton General Hospital, Elm Grove, Brighton