Effectiveness of screening in preventing blindness due to diabetic retinopathy

Aims Diabetes remains the commonest cause of blindness in the working age population of the UK, but little information exists about the individuals who are currently losing sight from this cause. We determined the current blindness incidence (1998-2000) in Newcastle Health District and the clinical characteristics of these patients. Methods Data were collected for 1998-2000 from the Royal National Institute for the Blind Liaison Office of the Newcastle Ophthalmology Department. The Ophthalmology Clinic notes on each individual were retrieved to verify clinical details, including previous eye diagnosis, dates of previous laser photocoagulation and eye surgery. The diabetes clinical records were studied to obtain information on type and duration of diabetes, blood pressure, HbA(1c) and other biochemical parameters. To ensure completeness of data, details of all patients registered blind attending the Newcastle Diabetic Centre were examined. Results Twenty-eight patients were registered blind due to diabetes and 26 partially sighted during this period. The annual incidence of blindness and partial sightedness due to diabetes in the Newcastle district were 0.35 and 0.56 per 1000, respectively. The average ages in the two groups were 65.9+/-12.5 and 67.2+/-12.3 years and duration of diabetes 15.5+/-13.9 and 15.3+/-10.6 years, respectively. Proliferative retinopathy accounted for 30 and maculopathy for 24 registrations. The times from ophthalmology referral to registration were 6.2+/-3.5 and 4.4+/-3.3 years in these groups, respectively. No cases resulted from false-negative screening. Conclusions In Newcastle district, where the retinal screening programme has been running since 1986, the rates of blindness and partial sightedness are less than one-third of those reported in the surveys prior to 1997, confirming that objectives of the St Vincent's declarations are being achieved.