Prevalence of diabetic retinopathy and sight threatening diabetic retinopathy in Hong Kong. Are we more or less at risk?

Abstract

INTRODUCTION: Diabetic retinopathy (DR) is a leading cause of visual impairment in the working age population. By the time diabetic patients seek help for clinicians, the condition may be advanced and irreversible. Timely detection of sight threatening DR (STDR) symptoms and timely laser treatment can prevent blindness due to diabetic eye disease. OBJECTIVES: The objectives of this study were: (1) To detect prevalence of DR and STDR in Hong Kong as a whole and in different clusters in Hong Kong; and (2) to compare with the global prevalence rate of DR. METHODOLOGY: Subjects with history of diabetes mellitus were screened at primary care outpatient clinics under the “Risk Assessment and Management Programme”. They underwent examination of visual acuity, anterior segment examination, and dilatation of pupils followed by mydriatic digital retinal fundus photography by trained optometrists. These photographs were systematically graded for DR according to the English national screening programme. The primary and secondary gradings were done by the optometrists and in event of any discrepancy, the arbitration grading was done by an ophthalmologist. The subjects were graded as having no DR, background DR, or STDR which included maculopathy, pre-proliferative DR and proliferative DR. RESULTS: In all, 145,888 subjects underwent screening for DR from November 2009 to August 2013. Of these, after excluding the subjects with ungradable photographs (n=8151; 5.6%), the prevalence of DR was 40.1% (95% CI: 39.9-40.4) for any DR and 10.2% (10.0-10.3) for STDR. The prevalence of maculopathy was 8.9% (95% CI: 8.8-9.0).The prevalence of proliferative DR was <1.0%. The prevalence of any DR in different clusters varied between 33.4 % and 49.8% while STDR prevalence varied between 7.3% and 11.9%. The prevalence of maculopathy varied between 8.0% and 10.1% amongst different clusters. The overall prevalence of DR in Hong Kong was 40% and that of STDR was 10.2%. The prevalence of STDR was similar to the global prevalence (10.2%) while the prevalence of any DR was higher than global prevalence ( 34.6%). The prevalence of maculopathy was slightly higher than global prevalence (7.5%). On the other hand, the prevalence of proliferative DR was <1.0% in our population as compared to the global prevalence of 7.0%. There was little variation in DR or STDR between clusters.