Diabetic Eye Screening: Evaluation and Comparison of the Grading Results Between Community and Hospital Eye Services

Diabetes is a significant global health crisis, affecting approximately 828 million individuals worldwide, including 5.6 million in the UK and an estimated 212,000 in Wales. Diabetic Retinopathy (DR) is a leading cause of blindness in the UK and severely impacts the working-age population. Effective screening programs are vital for early detection and intervention, as prolonged diabetes increases the risk of developing DR. Since 2003, Diabetic Eye Screening Wales (DESW) has coordinated DR screening in Wales, but no studies have assessed grading agreement across the screening pathway.

This retrospective study analysed data from January 2021 to December 2023, involving 762 eyes from 486 patients referred across different grading levels. The RxMx system was used to classify retinopathy and maculopathy. The agreement between primary graders (DESW) and secondary graders (community optometrists) was compared, along with that between secondary and tertiary graders (hospital eye services). Percentage agreement and weighted Cohen's Kappa were calculated to assess interobserver reliability.

The percentage agreement was 60.4% (weighted Cohen's Kappa of 0.423, indicating moderate agreement) between primary and secondary graders for retinopathy. For maculopathy, the agreement was 69.6% (weighted Cohen's Kappa of 0.42). Between secondary and tertiary graders, the percentage agreement for retinopathy was 61.5% (Kappa of 0.634, indicating substantial agreement), while for maculopathy, it was 75.0% (Kappa of 0.618).

The findings show fair agreement between primary and secondary graders and a substantial agreement between secondary and tertiary graders. These results highlight concerns regarding the reliability of current screening practices and suggest incorporating optical coherence tomography (OCT) to enhance grading accuracy. Additionally, implementation of personalised risk-based screening may help reduce the burden of DR on healthcare services, although consideration is necessary to prevent exacerbating existing health inequalities. An electronic system for shared imaging data could further improve screening reliability and grader competency assessment.