Effects of coloured light filtered spectacles on short sightedness

Intervention: Selective light filtering spectacles. Participants will be instructed to wear the selective light filtering spectacles which will be made with their prescription, for a minimum of ten hours a day, seven days a week for four weeks and not to use any other optical correction. The selective light filter is a specialised filter, classified as a Class I medical device. The filters selectively reduce light transmission for wavelengths in the middle of the visual spectrum, enhancing transmission of the short wavelength regions of the visual spectrum. Adherence will be monitored with a weekly text message sent from a lab phone asking how many days a week and for how many hours each day the spectacles were worn. This is a cross-over trial, participants will be randomly assigned to commence either the control or intervention arm first. In between both arms there will be a two week wash-out period where they will be asked to return to their habitual correction and baseline measurements will again be taken following the two week washout period prior to commencement of the other arm.