1. Global estimates of visual impairment: 2010;Pascolini;Br J Ophthalmol,2012
2. World Health Organization International statistical classification of diseases and related health problems http://apps.who.int/classifications/icd10/browse/2010/en
3. Global data on visual impairment in the year 2002;Resnikoff;Bull World Health Organ,2004
4. Vision 2020: The Right to Sight Global initiative for the elimination of avoidable blindness, Action Plan 2006-2011 http://www.who.int/blindness/Vision2020_report.pdf
5. Severe visual impairment and blindness in children in the UK;Rahi;Lancet,2003