The occurrence and causes of registered blindness in diabetes patients in Arhus County, Denmark

Purpose: To report the occurrence of registered blindness among diabetes patients in Arhus County, Denmark during 1993-2002. Methods: Data were obtained from a database of 7527 diabetes patients, which included all patients in the county who had been treated for or had experienced visual loss due to diabetic retinopathy since 1992. Of these, 1949 had type 1 diabetes and represented 90% of the type 1 diabetes patient population in the county, and 5459 had type 2 diabetes and represented 40% of the type 2 diabetes patient population in the county. Results: The point prevalence of legal blindness was 0.6% for type 1 and 1.5% for type 2 diabetes patients at January 1st, 2003. In type 1 diabetes patients, the major cause of blindness was proliferative diabetic retinopathy (PDR) (66.2% of all blind eyes); in type 2 diabetes patients the major causes were age-related macular degeneration (21.9%), PDR (18.0%) and diabetic maculopathy (DMac) (18.5%). During 1993-2002 there was a significant decrease in the number of blind eyes secondary to PDR (p = 0.008) in type 1 diabetes patients, and a significant increase in the number of blind eyes secondary to DMac (p = 0.005) in type 2 diabetes patients. Conclusion: The major challenge in reducing diabetes-related blindness is related to the detection and treatment of an increased incidence of diabetic maculopathy in type 2 diabetes patients.