Purpose: To estimate population-based incidence rates of registered blindness separately, to determine its main causes.
Methods: The files of all newly registered blindness-allowance recipients in Württemberg-Hohenzollern, Germany (population: approximately 5 million), between 1994 and 1998 were reviewed. From ophthalmological reports on file the fulfillment of the German criteria for blindness (visual acuity of 1/50 or less or equivalent reduction of visual function) was ascertained, and the causes of blindness were obtained. Incidence rates of blindness due to macular degeneration, glaucoma, cataract, optic atrophy, and diabetic retinopathy were estimated.
Results: There were 3531 newly registered blindness-allowance recipients (67.1% female; mean age, 72.8 +/- 21.0 years). Standardized incidence rates in the general population (per 100,000 person-years; 95% confidence interval): All causes 12.27 (11.87-12.68), macular degeneration 5.29 (5.02-5.55), cataract 3.32 (3.11-3.52), optic atrophy 2.86 (2.66-3.05), glaucoma 2.43 (2.25-2.61), diabetic retinopathy 2.13 (1.96-2.30), other or unknown causes 5.17 (4.91-5.43). In many cases, blindness was attributable to more than one cause. Assuming that incidence rates are the same in other parts of the country, 9,939 (9,608-10,270) new cases of blindness were estimated to occur in Germany per year.
Conclusions: The most common single cause of blindness was macular degeneration. Incidence rates of blindness due to such treatable conditions as glaucoma were also high. This finding suggests that the taking of measures for secondary prevention (e.g., early detection and optimal treatment of patients with glaucoma and diabetic retinopathy) should be intensified.