Richard Wormald1, Jennifer Evans2. 1. a Co-coordinating Editor Cochrane Eyes and Vision, Consultant Ophthalmologist, Moorfields Eye Hospital, London, and Honorary Senior Lecturer, Institute of Ophthalmology , University College London and London School of Hygiene and Tropical Medicine , London , UK. 2. b Co-coordinating Editor, Cochrane Eyes and Vision, and Assistant Professor, International Centre for Eye Health , London School of Hygiene and Tropical Medicine , London , UK.