1 International Centre for Eye Health, Clinical Research Department, London School of Hygiene & Tropical Medicine, Keppel Street, London, United Kingdom.
2 International Centre for Eye Health, Clinical Research Department, London School of Hygiene & Tropical Medicine, Keppel Street, London, United Kingdom; Indian Institute of Public Health, Public Health Foundation of India, ANV Arcade, 1 Amar Cooperative Society, Kavuri Hills, Madhapur, Hyderabad, Telangana, India.
3 The Queen Elizabeth Diamond Jubilee Trust, 128 Buckingham Palace Road, London, United Kingdom.