1 Research &Development, NIHR Biomedical Research Centre at Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London, UK.
2 Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, UK.
3 School of Human and Health Sciences, University of Huddersfield, Queensgate, Huddersfield GB-HD1 3DH, Great Britain.
4 Comprehensive Clinical Trials Unit, University College London, Great Britain.
5 Department of Primary Care and Population Health, University College London, Great Britain.