1. NIHR Biomedical Research Centre, Moorfields Eye Hospital Nhs Foundation Trust and UCL Institute of Ophthalmology, London, UK
2. Department of Surgery, Royal Victoria Infirmary, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK
3. Department of Paediatrics and Child Health, Faculty of Medicine and Health Sciences, Stellenbosch University and Tygerberg Hospital, Cape Town, South Africa
4. National Cancer Registry, National Health Laboratory Service, Johannesburg, South Africa
5. School of Public Health, University of the Witwatersrand, Johannesburg, South Africa