of diabetic retinopathy and maculopathy, with significantly elevated systolic and diastolic blood pressure, haemoglobin A1C, and total cholesterol; lower attained age; and younger age at diagnosis. Earlier onset of disease and higher levels of modifiable risk factors in south Asians make early detection of diabetes, annual referral for retinal screening, and intensive risk factor control key elements in addressing this health inequality (Levels 1,2) 2.4 INCIDENCE & PREVALENCE OF DIABETIC RETINOPATHY 2.4.1 Prevalence of diabetic retinopathy and sight threatening diabetic retinopathy In 1992, Klein16 reported results from the Wisconsin Epidemiological Study of Diabetic Retinopathy (WESDR study), which was a population-based study in southern Wisconsin of 996 insulin-taking younger-onset diabetic persons (given diagnoses of diabetes under 30 yrs.) and 1,370 patients given diagnoses of diabetes at age 30 years or older who were examined using standard protocols to determine the prevalence and severity of diabetic retinopathy and associated risk variables. Proliferative diabetic retinopathy (PDR) was found to be a prevalent complication - 23% in the younger-onset group, 10% in the older-onset group that takes insulin, and 3% in the group that does not take insulin. In 1995 Klein17 reported the incidence of macular oedema over a 10 year period to be 20.1% in the younger-onset group, 25.4% in the older-onset group taking insulin, and 13.9% in the older-onset group not taking insulin. (Level 1) In 1998, Kohner18 reported baseline retinopathy levels in 2964 patients with newly diagnosed type 2 diabetes enrolled in the United Kingdom Prospective Diabetes Study (UKPDS). Retinopathy, defined as microaneurysms or worse lesions in at least 1 eye, was present in 39% of men and 35% of women. Marked retinopathy with cotton wool spots or intraretinal microvascular abnormalities was present in 8% of men and 4% of women. (Level 1) In 2002, Younis19 reported baseline results from population screening in Liverpool of 831 people with Type 1 diabetes and 7231 people with Type 2 diabetes. The results showed a baseline for Type 1 of any DR 45.7%, PDR 3.7% and STED 16.4%. Baseline for Type 2 group of any DR 25.3%, PDR 0.5% and STED 6.0%. (Level 1) Individual case reports exist to show that children as young as 12 years of age can present with pre-proliferative DR20 or as young as 8 years with a duration of diabetes of some 5.6 years, with background diabetic retinopathy21 . (Level 3) Many studies exist on diabetic eye disease in different parts of the world22 - 33 all of which provide a picture of increasing concern with respect to the prevalence of this disorder (Levels 2 and 3) Two studies34 35 have demonstrated that, if one screens for type 2 diabetes, the prevalence of diabetic retinopathy in screen positive patients (7.6% and 6.8%) is 16 much lower than the prevalence in the known population of people with diabetes. (Level 3) Beulens36 reported that baseline retinopathy levels (ETDRS ≥20) of 1602 patients with type 2 diabetes in the ADVANCE study was 40.1% indicating a high prevalence of the early features of microvascular damage. (Level 1) 2.4.2. Incidence and progression of DR In 1981, Palmberg37 described a study of the natural history of diabetic retinopathy in 461 people with juvenile-onset insulin-dependent diabetes mellitus (IDDM). At diagnosis no DR was found, with prevalence of 50% at 7 yrs duration and 90% at 17- 50 yrs duration. Proliferative diabetic retinopathy (PDR) was first seen at 13 yrs, with 26% prevalence at 26-50 yrs duration. (Level 1) In a longitudinal analysis of the WESDR study in 1984 and 1989, Klein38-41 reported that for the 154 people with IDDM diagnosed > 30 yrs. with no DR at first visit, 47% developed DR after 4 yrs. For the 418 people with IDDM diagnosed > 30 yrs. with no PDR at first visit, 7% developed PDR after 4 years and worsening of DR in 34%. For the 320 non IDDM diagnosed > 30 yrs. with no DR at first visit, 34% (developed DR after 4 yrs. For the 486 non IDDM diagnosed > 30 yrs. with no PDR at first visit, 2% developed PDR after 4 years and worsening of DR in 25%. (Level 1) Further studies that have shown clear evidence that sight-threatening diabetic retinopathy has a recognisable latent or early symptomatic stage 42-53 . The Diabetes Control and Complications Trial54-56 (DCCT) included 1441 people with type 1 DM, 726 with no DR at base line (the primary-prevention cohort), and 715 with mild to moderateretinopathy (the secondary-intervention cohort), with mean follow-up of 6.5 years. For the primary-prevention cohort, intensive therapy reduced the mean risk for the development of DR by 76 % (CI 62-85 %), compared with conventional therapy. For the secondary-intervention cohort, intensive therapy slowed the progression of DR by 54 % (CI 39-66 %) and reduced the development of PDR or severe NPDR by 47 % (CI 14-67 %). (Level 1) The United Kingdom Prospective Diabetes Study18 57-60 recruited 3867 with type 2 DM and the effect of intensive blood-glucose control with sulphonylureas or insulin was compared with conventional treatment. Compared with the conventional group, there was a 25% risk reduction (7-40, p=0.0099) in the intensive group in microvascular endpoints, including the need for retinal photocoagulation. Patients allocated metformin, compared with the conventional group, had risk reductions of 32% (95% CI 13-47, p=0.002) for any diabetes-related endpoint. (Level 1) A systematic review published by Williams27 in 2004 on the epidemiology of diabetic retinopathy and macular oedema concluded that studies of sufficient size to stratify for age and duration of eye disease show an increase in DR in older age groups with long-standing disease.(Level 1) Grauslund61 reported the 25 year incidence of proliferative retinopathy among population-based cohort of 727 type 1 Danish diabetic patients was 42.9%.(Level 2) 17 In 2008 and 2009, Klein62 63 reported on the 25-year cumulative progression and regression of diabetic retinopathy (DR) and on the 25-year cumulative incidence of macular edema (ME) and clinically significant macular oedema (CSME) in the Wisconsin