Document resource
Background Diabetic retinopathy screening in Wales currently involves pharmacological pupil dilation, however Diabetic Eye Screening Wales (DESW) are planning a robust evaluation of the Topcon NW500 non-mydriatic fundus camera, for use without dilation. To inform this, a scoping review was conducted to assess whether non-mydriatic imaging using the Topcon NW500 or comparable devices can provide sufficient image quality for diabetic retinopathy grading without pharmacological pupil dilation, and to identify factors associated with ungradable images in non-mydriatic screening.Methods Structured searches of bibliographic databases and grey literature identified studies published since 2015. Studies were screened in duplicate against prespecified inclusion criteria. Included studies were appraised with study design specific checklists. Findings were summarised to provide an overview of the research landscape.Results Fifteen studies were included in the review. Varying levels of diagnostic accuracy among non-mydriatic 45° fundus cameras were reported. Only one study met the British Diabetic Association’s recommended thresholds for both sensitivity (≥80%) and specificity (≥95%), though methodological concerns limit confidence in this result. Heterogeneity in camera models, imaging protocols, and reference standards limits comparability across studies and restricts the generalisability of findings. Evidence on factors associated with ungradable images was limited. Older age was the most consistently associated factor, with two studies reporting significantly increased odds of ungradable images in older populations. Single-study findings suggested increased odds of ungradable images associated with ocular or visual factors, male sex, non-white ethnicity, smoking, and lower patient throughput.Conclusion Studies evaluating non-mydriatic fundus cameras showed limited achievement of established diagnostic accuracy thresholds. Factors linked to ungradable images were sparse, but older age emerged as a risk factor, alongside single-study associations with various eye conditions and demographic factors. Crucially, no studies assessed the Topcon NW500, which limits the relevance of existing findings to current practice in Wales, and underscores the need for a robust local evaluation.