Screening school aged children and adolescents for reduced vision caused by the need for glasses

Worldwide, the leading cause of reduced vision in children is an unidentified need for them to wear glasses. The reduced vision that results from abnormal focusing (refractive error) can cause the children to screw up their eyes and complain of headaches. Reduced vision may affect academic performance, choice of occupation and socio-economic status in adult life. Genetic and environmental factors are known to affect the development of refractive error; it is also more common in certain racial groups. Short sightedness has become the commonest eye condition. The need to correct refractive error is determined by its effect on vision. Normal vision can usually be restored by wearing corrective glasses or contact lenses. However, there is some evidence that correction may cause an error to persist where it might otherwise have resolved or reduced naturally. Vision screening is used widely but is concentrated in developed countries; in developing countries it may serve the purpose of providing access to health care. The value of screening after school entry has been queried. Programmes vary with regard to testing personnel, set threshold for failure, frequency and setting. The disability caused by a vision deficit has not been quantified and the optimum age and number of occasions for screening have not been established. The aim of this review was to find studies that evaluated the effectiveness of school vision screening programmes in first identifying children with reduced vision. No eligible randomised studies were found. There is a clear need for reliable evidence to measure the effectiveness of vision screening. A narrative synthesis of other retrieved studies was undertaken in order to explain current practice.