For the intervention study, at the initial visit all participants will undergo a number of visual assessments including measurement of the shape and length of the eye, focusing ability over a range of distances, eye muscle balance, vision at a range of different contrasts, pupil size and quality of stereovision. Measures of the participant's spectacle prescription by objective and subjective means will also be undertaken following the instillation of eye drops to relax the muscles of the eye and to dilate the pupils. Subjects in the intervention groups will be reassessed after a period of six months to establish a measure of natural eye growth prior to being fitted with contact lenses. Parents and children will also be asked to complete a background questionnaire at this visit. The first visit is expected to last around 90 minutes.