New imaging technologies as well as advances in big data processing and increased internet access all have the potential to further improve current methods of screening for diabetic retinopathy, according to Andrzej Grzybowski MD, PhD.
“Diabetic retinopathy (DR) screening programmes are effective in detecting early sight-threatening DR. We are seeing a trend towards more telemedicine applications with improved imaging technologies, automatic assessment of fundus photographs, and more individualised risk assessment. When properly implemented, all of this can dramatically lower the cost of DR screening and make it possible to offer treatment to diabetic patients around the world at manageable costs,” he told delegates attending the European Society of Ophthalmology (SOE) 2017 Congress in Barcelona, Spain.
In an overview of current DR screening programmes in Europe, Dr Grzybowski, Professor of Ophthalmology at University of Warmia and Mazury, Olsztyn, Poland, and Head of Department of Ophthalmology at Poznan City Hospital, Poznan, Poland, said that there was considerable disparity in the methods used from one country to another.
While the gold standard for retinal diabetic photography is seven-field stereo colour ETDRS, this type of fundus photography is time-consuming, expensive, and requires an experienced photographer, noted Dr Grzybowski. Digital photography of the eye seems to be the more efficient and cost-effective method of screening, he added.
In England, for instance, the DR screening programme started in 2006, and covers all diabetic patients aged 12 years or older with light perception or more in at least one eye. Screening is performed annually at static and mobile screening locations using digital fundus cameras. The protocol consists of two-field colour eye fundus photographs: one of the macula centre and one of the optic disc centre taken after pupil dilation. Retinal photographs are read in a few centralised grading centres.
In France, the first tele-medical screening for DR started in 2002 in the Paris region. A fundus camera was used by orthoptists to capture five-colour photographs of 45 degrees of the central and peripheral retina, with the images sent via internet to a grading centre for assessment. This was followed by OPHDIAT, a tele-medical network screening system for DR in the Île-de-France area.
This system used 16 peripheral screening centres equipped with non-mydriatic cameras, where fundus photographs taken by technicians were linked by telemedicine to a reference centre, where ophthalmologists graded the images. During a 28-month evaluation period of OPHDIAT, 15,307 DR screening examinations were performed.
Retinal photographs of at least one eye could not be graded in 1,332 patients (9.7%), and diabetic retinopathy was detected in 3,350 patients (23.4%). After the screening examination, 3,478 patients (25.2%) were referred to an ophthalmologist for either DR, cataract, and/or non-gradable photographs.
In Spain, Andonegui et al conducted a 24-month DR screening study based on digital retinal images taken and initially graded by trained general practitioners. When the interpretation of pictures was uncertain, the GPs sent the patient to the ophthalmologist to assess retinal status. The study authors concluded that proper training for GPs can significantly improve DR screening and help to save patients’ sight.
In Ireland, a community-based initiative was established in 2010 involving GPs, local optometrists and ophthalmologists to screen patients older than 18 years of age with type 1 or 2 diabetes using digital fundus cameras. Two-field photos of the retina (macula and optic disc) were graded by specialist software and the results were sent electronically to GPs who were responsible for referral to ophthalmic specialists.
The study, which was performed from January until June 2011, found 26% of patients with DR and highlighted the need for a national DR screening programme in Ireland, said the authors.
Having studied DR screening programmes around the world, Dr Grzybowski said that clear conclusions could be drawn from the experience of different countries in drawing up more efficient and effective programmes.
“It is clear that single-field non-mydriatic monochromatic digital photography is a sensitive and specific alternative to the traditional reference standard of seven-field stereoscopic colour fundus photography and ophthalmoscopy. Trained graders remotely interpreting non-mydriatic images achieved greater sensitivity than ophthalmoscopy and comparable results with seven-field photography,” he said.