Evaluation of spatial distribution of initial marking strategy among inexperienced graders in diabetic retinopathy: A retrospective cross‐sectional analysis

Abstract Background Manual diabetic retinopathy (DR) grading may prefer certain regions and underestimate others. It is unclear if inexperienced graders' initial marking strategy reflects a specialist's marking pattern. Aims By the virtual ocular learning platform (VIOLA), we evaluated if initial DR‐lesion markings among inexperienced graders spatially corresponded to a specialist‐based lesion map. Materials and Methods We used retinal 6‐field VIOLA images with at least 500 DR‐lesion markings covering all DR‐levels (0–4) according to the international clinical diabetic retinopathy (ICDR) scale. We divided images into quadrants and counted the initial three markings per lesion type, per image, per grader. A retinal specialist served reference for annotation of all DR‐lesions. The primary outcome was difference in spatial distribution of DR‐markings across quadrants relative to the reference, further characterised with spatial metrics. p ‐Value < 0.05 indicated statistical significance. Results Across 24 images, 97 graders marked 16 925 DR‐lesions: 1633 microaneurysms (MA), 3228 haemorrhages, 1549 hard exudates (HE), 3081 cotton wool spots (CWS), 3844 intraretinal microvascular abnormalities (IRMA), 1832 new vessels (NV) and 1758 panretinal photocoagulation scars (PRP). A difference was observed across all lesion types ( χ 2 ‐test, p < 0.001) relative to the reference lesion map. Discussion Most lesion types demonstrated high sensitivity, but low PPV, indicating a liberal marking approach. Distribution of initial markings from inexperienced graders spatially misaligns with a specialist‐derived lesion map across all lesion types. Conclusion As the ICDR‐scale depends on identifying the most severe lesion type, systematically inconsistent search strategies may pose a risk for overlooking important lesions under time constraints. The results support the promotion of attention guiding during DR‐training.