Vision and Eye Research Unit, Postgraduate Medical Institute, Anglia Ruskin University, Cambridge, UK. Electronic address: rb@rupertbourne.co.uk. Department of Health Statistics and Information Systems, WHO, Geneva, Switzerland. Department of Genes and Environment, Division of Epidemiology, Norwegian Institute of Public Health, Oslo, Norway. Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK. School of Computer Science and Heinz College, Carnegie Mellon University, Pittsburgh, PA, USA. Vision and Eye Research Unit, Postgraduate Medical Institute, Anglia Ruskin University, Cambridge, UK. Department of Ophthalmology, Universitätsmedizin, Mannheim, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany. LV Prasad Eye Institute, Hyderabad, India. College of Optometry, Nova Southeastern University, Fort-Lauderdale-Davie, FL, USA. African Vision Research Institute, University of Kwazulu-Natal, South Africa; Brien Holden Vision Institute, Sydney, NSW, Australia. NHMRC Centre for Clinical Eye Research, Flinders University, Adelaide, SA, Australia. International Health and Development, Geneva, Switzerland. Melbourne School of Public Health, University of Melbourne, Melbourne, VIC, Australia.