What is the prevalence of visual impairment in the general and diabetic populations: are there ethnic and gender differences? - Hayward,L.M.; Burden,M.L.; Burden,A.C.; Blackledge,H.; Raymond,N.T.; Botha,J.L.; Karwatowski,W.SS.; Duke,T.; Chang,Y.F. (Diabet Med, 2002)