Quality assurance in diabetic retinal screening in South Africa

Steve Cook, Roger T Staff, Keith A Goatman, John A Olson, Scottish Diabetic Retinopathy Screening collaborative


Background. Diabetic retinopathy (DR) is an important biomarker for microvascular disease and blindness. Digital fundus photography is a cost-effective way of screening for DR. Access to DR screening is difficult for many South Africans with diabetes.

Objective. To perform external quality assurance (EQA) on graders registered in the Ophthalmological Society of South Africa DR screening programme.

Methods. Graders registered on the South African (SA) Diabetic Register website were invited to participate in the study. The Scottish EQA software system was used to enable on-line grading of 100 retinal photographs. Expert National Health Service graders provided the consensus expert grading for the image set.

Results. Two hundred and sixty-one participants completed the EQA process, including nine ophthalmologists, 243 optometrists, and nine other graders. A wide range of outcomes were demonstrated, with a mean sensitivity of 0.905 (range 0.286 - 1.000) and mean specificity of 0.507 (0.000 - 0.935). The mean diagnostic odds ratio was calculated to be 12.3 (range 0.147 - 148.2).

Conclusions. This is the first quality assurance study conducted with SA healthcare professionals. The outcomes are of interest to all stakeholders dealing with the diabetes epidemic. The disparity in grader performance indicates room for improvement. The results demonstrate a high referral rate to ophthalmology, suggesting that on average graders are performing safely, but with a high number of inappropriate referrals.

Authors' affiliations

Steve Cook, The Eye Centre, East London, Eastern Cape, South Africa; Department of Ophthalmology, Faculty of Health Sciences, Walter Sisulu University, Umtata, Eastern Cape, South Africa

Roger T Staff, Aberdeen Biomedical Imaging Centre, University of Aberdeen, Aberdeen, Scotland, UK; Aberdeen Royal Infirmary, NHS Grampian, Scotland, UK

Keith A Goatman, School of Medicine and Dentistry, University of Aberdeen, Scotland, UK

John A Olson, School of Medicine and Dentistry, University of Aberdeen, Scotland, UK; Retinal Screening, Aberdeen Royal Infirmary, NHS Grampian, Scotland, UK

Scottish Diabetic Retinopathy Screening collaborative, NHS Scotland

Full Text



Diabetic retinopathy; Quality assurance; Screening

Cite this article

South African Medical Journal 2014;104(10):700-704. DOI:10.7196/SAMJ.8678

Article History

Date submitted: 2014-07-14
Date published: 2014-09-03

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