Incidence of blindness in southern Germany between 1990 and 1998.

Aims/hypothesis: A reduction of diabetes-related blindness by at least one third was declared a primary objective for Europe in 1989 (St. Vincent Declaration). To ascertain a potential change of incidence rates, we collected data on blindness in a German district (population: about 5 million) over 9 years.
Methods: We obtained complete lists of newly registered blindness-allowance recipients between 1990 and 1998 and population data on Württemberg-Hohenzollern, Germany. We estimated incidence rates of blindness in the general population and the diabetic population. To ascertain any time trend, we applied Poisson regression models.
Results: There were 6371 newly registered blindness allowance recipients (1990-1998). Of these 67% were women and 27 % had diabetes. Mean age was 71.7 years. Standardised results in the diabetic population (incidence rates per 100,000 person-years; standard: diabetic population; 95 % CI): 1990: 72 (61;82); 1991: 88 (76;100); 1992: 77 (67;88); 1993: 82 (71;93); 1994: 62 (53;72); 1995: 82 (71;93); 1996: 70 (60;80); 1997: 69 (59;79); 1998: 59 (49;68). The Poisson model estimated a 3 % decrease of incident blindness in the diabetic population for each year (Relative risk per year 0.97; CI: 0.95; 0.99). No significant change could be observed in the non-diabetic population (Relative risk: 0.99; CI: 0.98; 1.00). Relative risks for each year varied between sub-groups according to sex, diabetic status and cause of blindness between 0.94 and 1.01.
Conclusion/interpretation: A slight reduction of incident blindness could be shown but a reduction by one third has not been reached. Several possible sources of bias in the data have to be considered.