Prevalence of diabetic retinopathy in patients with recently diagnosed diabetes mellitus.

BACKGROUND The severity of diabetic retinopathy is well known to have a close association with the duration of diabetes mellitus. Patients with recently diagnosed diabetes should have adequate eye examinations to eliminate the possibility of diabetic retinopathy being present because there is no accurate means of determining the duration of the disease. The prevalence of diabetic retinopathy in type 2 diabetic patients with known duration up to one year was investigated in the present study. METHODS A centre for diabetic retinopathy screening was set up in a community in Hong Kong. The screening procedures included history taking, visual acuity measurement, anterior ocular health assessment and retinal examination by fundus photography. Fundus photographs were taken in nine different positions of gaze through natural or dilated pupils. Using the criteria recommended by the American Optometric Association the retinopathy was graded in severity. 'Recently diagnosed diabetes mellitus' was defined as having diabetes diagnosed by a physician within the previous year. RESULTS A total of 12,112 patients having their first visits to the centre were recruited from 2006 to 2009. Among them, 3,510 patients had recently diagnosed diabetes. The mean age of patients was 59.5 years. The prevalence of diabetic retinopathy was 18.2 per cent (639 patients) among the recently diagnosed diabetic patients. Most of the patients had mild non-proliferative diabetic retinopathy. In these 639 patients, approximately seven per cent had sight-threatening retinopathy that included significant macular oedema, all of whom required monitoring. The presence of hypertension or smoking was not significantly associated with the prevalence of diabetic retinopathy in recently diagnosed diabetic patients. CONCLUSIONS Screening for diabetic retinopathy is important for newly diagnosed diabetic patients. In Hong Kong, the prevalence of diabetic retinopathy was alarmingly high and some patients had already developed sight-threatening retinopathy that included macular oedema. Most of them had no symptoms until the retinopathy progressed and they developed macular oedema. A systematic screening program in the community is needed for early detection and to reduce blindness in diabetic patients.