1. From the Department of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, United Kingdom; the
2. Department of Community Ophthalmology, Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India; the
3. Centre for Clinical and Population Sciences and
4. Dipartimento di Scienze Otorino-Odonto-Oftalmologiche e Cervico Facciali, Sezione di Oftalmologia, Universita` degli Studi di Parma, Parma, Italy.
5. Ophthalmology and Vision Science, Queen’s University Belfast, Northern Ireland, United Kingdom; and the