Progression of diabetes retinal status within community screening programmes and potential implications for screening intervals

Objective
This study aimed to follow the natural progression of retinal changes in patients with diabetes. Such information should inform decisions with regard to the screening intervals for such patients

Research Design and Methods
An observational study was undertaken linking the data from seven diabetes retinal screening programmes across the UK for retinal grading results between 2005 and 2012. Patients with absent or background retinopathy were followed up for progression to the endpoints referable retinopathy, and treatable retinopathy (proliferative retinopathy).

Results
In total 354,549 patients were observed for up to four years during which 16,196 progressed to referable retinopathy. Of patients with no retinopathy in either eye for two successive screening episodes at least 12 months apart between 0.3 (95% confidence interval 0.3-0.8)% and 1.3 (1.0-1.6)% progressed to referable retinopathy and rates of treatable eye disease were less than 0.3% at two years. The corresponding progression rates for patients with bilateral background retinopathy in successive screening episodes was 13-29% and up to 4% respectively in the different programmes.

Conclusions
It may be possible to risk stratify patients according to baseline retinal criteria into low and high risk of progressing to proliferative retinopathy. Screening intervals for such diverse groups of patients could safely be modified according to their risk,