AbstractGet full access to this articleView all access options for this article.Get accessReferences1.Report of the ninth meeting of the WHO programme advisory group on the prevention of blindness. World Health Organization, Geneva, WHO/PBL/1991; 22: 212. Maertens K Bokanisa N . An inexpensive operating loupe. Trop Doct 1986; 16: 139–403. Safir A . Refraction and clinical optics. London: Harper & Row, 1988: 77