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.

Inclusion Criteria:

• Subject must meet all the inclusion criteria below to participate in this study.

  1. Written Informed Consent form from parent / legal guardian and assent from child subject has been obtained

  2. Is between 7 to 10 years of age at start of study intervention which is 2 January 2025 or 1 January 2026

  3. Studying in either Primary 2 or 3 classes of the participating school(s) in academic year 2025 or 2026.

  4. Presenting visual acuity or best corrected visual acuity (BCVA) better or equal to LogMAR 0.2 (equivalent to Snellen 6/9 or better) in each eye

  5. Normal Intraocular pressure (not more than 21mmHg)

  6. No ocular conditions (e.g., optic nerve disease, glaucoma, retinal diseases) except for refractive error.

  7. No ocular conditions affecting the accuracy of the ophthalmic examinations

  8. In good general health with no significant systemic diseases that may affect eye health

     Exclusion Criteria:

• All subjects meeting any of the exclusion criteria at baseline will be excluded from participation.

  1. Previous or ongoing myopia control treatment (including but not limited to orthokeratology, atropine, pirenzepine, myopia control spectacle and contact lenses, light therapy)
  2. Ongoing participation in other myopia prevention and control research trials
  3. Any systemic or neurologic diseases (e.g. cancer, epilepsy, Kawasaki disease) known to affect eye health or make the participant vulnerable to the ophthalmic examinations (e.g., light flash)
  4. Any other conditions precluding adherence to the protocol including unwillingness to refrain from myopia control treatment for the duration of the study

This study is a double-blind, semi-randomised controlled trial in which neither the study participants, the investigators nor study personnel responsible for measuring and analysing the study outcomes will be aware of the treatment given.

Study team will document consent to participate and non-objection response to classroom lighting change. A 100% non-objection rate from the parents of students within one classroom will be required prior to changing the classroom lighting. Randomization: Classrooms randomly be assigned into technical or other arms (cluster). Students from classrooms not included in the technical arms will be randomized into control or digital intervention arm.

For the purpose of maintaining double-blind, all participants (parents) will be given LightUP application that will either be sham or interventional. Only a group of unmasked study personnel will know the treatment allocation and they will not be involved in data collection and analysis of results/data.