1. International Centre for Eye Health, Clinical Research Department, London School of Hygiene and Tropical Medicine (LSHTM), London, England
2. Kitale Hospital and Zonal Ophthalmologist, North Rift, Kenya
3. Glasgow Centre for Ophthalmic Research, NHS Greater Glasgow and Clyde, Glasgow, Scotland
4. MRC Tropical Epidemiology Group, Faculty of Epidemiology and Population Health, LSHTM, London, England