Diabetic retinopathy screening in a high-latitude rural population of Northern Norway

To estimate the prevalence of diabetic retinopathy (DR) and diabetic macular edema (DME) in Finnmark, the northernmost county in Norway, and to assess the safety and quality of a two-step screening routine utilizing certified nurse or optometrist as primary graders. This cross-sectional study included 300 patients attending for routine DR screening at Kirkenes Hospital between October 2021 and December 2022. Retinal images were graded independently by a certified nurse/optometrist and an ophthalmologist. Discrepancies were resolved by a retina specialist and intergrader agreement was assessed. The prevalence of any DR was 56.3% (82.8% in type I diabetes (T1D), 53.5% in type II (T2D)). DME based on photography was present in 11.3%, and in 12.3% based on OCT. Severe non-proliferative DR (NPDR) or proliferative DR (PDR) was observed in 37.9% of participants with T1D and 12.2% of those with T2D. Intergrader agreement for DR grade and DME based on photography was high; Cohen’s weighted kappa (k) was 0.96 and 0.91 respectively. Intergrader agreement for identifying referable DR was 0.97. The prevalence of DR and DME in this rural northern Norwegian hospital-based cohort was higher than previously reported Norwegian estimates, likely partly due to differences in population characteristics and screening methodology. The two-step screening model demonstrated high accuracy in differentiating referable from non-referable DR, supporting its implementation to improve screening efficiency while maintaining diagnostic safety.