http://www.who.int/topics/blindness/en/
http://www.who.int/mediacentre/news/releases/pr79/en/ http://whqlibdoc.who.int/bulletin/2001/issue3/79(3)227-232.pdf
http://www.who.int/blindness/en/index.html
http://www.nature.com/eye/journal/v19/n10/full/6701973a.html
http://www.who.int/mediacentre/factsheets/fs282/en/index.html
http://www.who.int/features/factfiles/vision/04_en.html
http://www.who.int/features/factfiles/blindness/blindness_facts/en/index7.html
http://www.who.int/bulletin/volumes/82/11/en/844.pdf