Epidemiology of diabetic retinopathy and an assessment of screening intervals

This thesis was an observational study to retrospectively examine the prevalence and incidence of DR and its associated risk factors from two screening services (Wales and Johannesburg, South Africa) in order to determine safe screening intervals in persons without evidence of DR at initial screening based on digital photography. Between 2005 and 2009 a total of 135,152 persons with diabetes over 12 years of age in Wales were screened. However, a total of 43,759 persons were excluded from analysis as they did not have their type of diabetes recorded (29,807) or where it was recorded it was outside of the pre-specified age at diagnosis of diabetes range of ≥30 years for type 2 DM and