Evidence‐based Danish guidelines for screening of diabetic retinopathy

Abstract

Purpose: Diabetic retinopathy (DR) is among the leading causes of visual loss in the working-age population. It is generally accepted that screening of DR is costeffective and can detect DR before it becomes sight-threatening to allow timely treatment. Methods: A group of retinal specialists was formed by the Danish Ophthalmological Society with the aim to formulate contemporary evidence-based guidelines for screening of DR in order to implement these in the Danish screening system. Results: We hereby present evidence for DR-screening regarding (1) classification of DR, (2) examination techniques, (3) screening intervals and (4) automated screening. It is our recommendation that the International Clinical Retinopathy Disease Severity Scale should be used to classify DR. As a minimum, mydriatic two-field disc-and macular-centred images are required. In the case of suspected clinically significant diabetic macular oedema, supplementary optical coherence tomography can increase the diagnostic accuracy. There is solid evidence to support a flexible, individualized screening regimen. In particular, it is possible to prolong screening intervals to 24-48 months for patients with no or mild nonproliferative diabetic retinopathy (NPDR), but it is also possible to use extended intervals of 12-24 months for patients with moderate NPDR given that these are well-regulated regarding glycaemic control (HbA1c ≤ 53 mmol/mol) and blood pressure (≤130/80 mmHg). Automated screening of DR is encouraging but is not ready for implementation at present. Conclusion: Danish evidenced-based guidelines for screening of DR support high-quality imaging and allow flexible, individualized screening intervals with a potential for extension to patients with low risk of DR progression.

Is automated screening for diabetic retinopathy indeed not yet ready as stated by Grauslund et al.?

“…In line with our conclusion, we have noted that in a more recent article, the first author of the Danish Guideline article, J. Grauslund, appears to agree, stating that 'Considering both strengths and limitations, as well as the high performance of deep learning-based algorithms, automated DR classification using deep learning could be feasible in a real-world screening scenario' (Nielsen et al 2019 (Grauslund et al 2018). The guidelines address the issue of whether or not automated methods of image analysis should be applied in DR screening as a means of limiting costs and promoting speed and efficacy.…”

“…Editor, I n a recent paper by Grauslund et al (2018), the evidence-based guidelines for screening of diabetic retinopathy (DR) in Denmark were presented. The authors addressed several aspects of screening: classification of DR, examination techniques, screening interval and the possible role of automated screening.…”

“…Last year, 7.4% of patients in the Danish screening system met this threshold (Dansk Diabetes Database National arsrapport 2017/2018), which is a stark contrast to the 0.7% who require referral for active PDR. The patients that Google would refer to the specialist level, whereas we service them at the screening level, typically in an outpatient clinic with comprehensive one-stop diabetes service, are the 3.8% of patients who have nonproliferative DR, the 0.7% with severe NPDR and the 2.2% with stabile proliferative DR (Grauslund et al 2018). This practice saves 9 out of 10 patients with inconvenience of going to the ophthalmologists' office, which is likely to promote compliance and reduce costs.…”

Optos wide‐field imaging versus conventional camera imaging in Danish patients with type 2 diabetes

“…According to the current guidelines from the Danish Ophthalmological Societies, all fundus images should be graded according to the Proposed International Clinical DR and Macular Edema Severity Scales (Grauslund et al. ). The SDCC grading scale is similar to the scale proposed by Wilkinson et al., except that abnormalities are assessed for the entire image and not in quadrants as suggested by Wilkinson et al.…”

“…In Denmark, screening is largely conducted from retina photos using advanced retina fundus cameras with manual interpretation of the image by specialized ophthalmologic staff (Grauslund et al. ). At present, the gold standard is the early treatment diabetic retinopathy study (ETDRS) fundus photography protocol which requires pharmacological mydriasis to depict seven individual, stereoscopic images, each covering 30° of the posterior retina.…”