Optimizing Light Exposure for Myopia Prevention and Control (LightSPAN)

The goal of this clinical trial is to evaluate whether the optimization of daily exposure to light in primary school children can lead to better myopia prevention and control. The trial also aims to better understand the impact of light exposure on sleep and cognitive performance in children. This trial has 3 arms namely, (1) a technical intervention arm, (2) a digital intervention arm, and (3) a control arm. 1. technical intervention - which involves changing of classroom lighting in primary schools to ceiling lights that mimic the spectral composition of sunlight and fluctuates in intensity. Parents of children within that arm will have a sham smart-phone application (s-LightUP) 2. digital intervention - which involves standard classroom lighting and giving parents an interventional smart-phone application (i-LightUP) that will be coupled with their child's light and activity sensor (wrist worn device ). The interventional app will provide individually tailored recommendation based on their children's behaviour (data feedback that is collected from the light and activity monitoring watch). The interventional app would then send reminder prompts/notifications to encourage parents help their children achieve required amounts of myopia-preventive light quantum target set per day. 3. Standard care or control group which involves standard classroom lighting and parents having a sham smart-phone application (s-LightUP) Participants will: * be randomised to receive either no intervention (control group), technical intervention (light intervention that mimics sunlight) or digital intervention (parents having an app that syncs with child's light and activity sensor which will provide feedback to parents to encourage and recommends increment of outdoor activities and hours). * have their myopia progression monitored every 6 monthly and cognitive assessment done once every 3 months over a year. * wear the light and activity sensor watches throughout the 1-year study period as much as possible (minimum 1 week per month) except for wet water activities such as swimming, diving and showering for research data collection purpose.

The primary objective of the study is to evaluate whether the optimization of daily exposure to light in primary school children can lead to better myopia prevention and control. To do so, we will evaluate the effectiveness, safety and feasibility of: 1. Arm 1: technical intervention which involves spectro-temporal refinement of classroom lighting in primary schools using full spectrum light emitting diodes (LEDs) (CCT: 4000K) in addition to intermittent fluctuations in light levels. Parents of children in that arm will have access to a sham version of the LightUP mobile application to facilitate communication with the study team and questionnaire collection during the study. 2. Arm 2: digital intervention which involves optimization of daily light exposure using an individualised behaviour-changing smart-phone application (Interventional LightUP application) coupled with child-worn light and activity sensors to provide parents with an individually tailored recommendation to adapt their children's behaviour and provide them with the required amounts of myopia-preventive light quantum/day. + standard classroom lighting As compared to: 3. Arm 3: Standard care or control group which involves standard classroom lighting and no access to the interventional version of the LightUP application. Parents of children in that arm will have access to a sham version of the LightUP mobile application to facilitate communication with the study team and questionnaire collection during the study. Our study will also lead to the following scalable and implementable outcomes: 1. evidence-based lighting designs and policy recommendations for classrooms; 2. a user-friendly, smart digital eyecare companion that aligns perfectly with Singapore's Smart Nation Initiative. A secondary objective of this study is to better understand the impact of light exposure on sleep and cognitive performance in children. This will be achieved through continuous wrist actigraphy monitoring and through cognitive assessments, performed in classrooms, using tablets (one tablet/child). The assessment consists of validated, child-adapted, higher cognitive tasks testing the following constructs: impulse control, spatial working memory, content working memory, cognitive flexibility, reaction time, and processing speed.