Prevalence and risk factors for diabetic retinopathy in a cross-sectional population-based study from rural southern China: Dongguan Eye Study

RESEARCH QUESTION: The current population-based study aimed to investigate the prevalence of diabetic retinopathy (DR) and risk factors among residents over 40 years old in the rural area of Dongguan, southern China. STUDY DESIGN: The Dongguan Eye Study was a population-based study from September 2011 to February 2012. SETTING: The area was set in the rural area of Dongguan, southern China. PARTICIPANTS: Adult rural population aged 40 or older. INTERVENTION: Participants underwent haematological, physical, ophthalmic examinations and completed a questionnaire regarding lifestyles and systemic medical conditions. PRIMARY AND SECONDARY OUTCOME MEASURES: The frequency and risk factors of visual impairment and the major vision-threatening eye diseases. RESULTS: Of the 8952 Han Chinese, 1500 were diagnosed with type 2 diabetes mellitus (T2DM) with an average age of 59.5±11.1 years, and 1310 participants with fundus photography results were analysed. Standardised prevalence rate of DR was 18.2% for all patients with diabetes, 32.8% for the patients with previously diagnosed diabetes and 12.6% for newly diagnosed patients with T2DM. The prevalence rate of male DR was significantly higher than that of female DR (23.0% vs 14.1%, p<0.001). No significant difference was found in age-specific prevalence of DR. In diabetic patients, the prevalence rates of vision-threatening diabetic retinopathy, diabetic macular oedema and clinically significant macular oedema were 2.5%, 2.8% and 0.9%, respectively. Male gender, higher education level, longer duration of diabetes mellitus (DM), higher systolic blood pressure and glycosylated haemoglobin were independent risk factors for DR development in patients with diabetes. CONCLUSION: A relatively lower prevalence of DR was found among the participants with T2DM in residents over 40 years in the rural area of southern China. Thus, an ophthalmic examination is recommended, especially for individuals with DM and DR risk factors. There is a need to increase awareness and education on DM and DR, especially in subjects with DR risk factors to reduce the incidence of DR and macular oedema.