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Controversy Over New Diabetic Retinopathy Screening Interval

Implementation this month of a longer screening interval for diabetic eye disease for patients deemed 'low risk' could result in delays in critical hospital referral, researchers from a London-led team have warned. 

Their study of over 80,000 people suggested that moving from annual to biennial screening would lead to treatment delays, with potential sight loss for some.

In 2016, the UK National Screening Committee recommended annual eye checks to detect diabetic retinopathy for people at high risk of sight loss, and 2-yearly checks for those considered at low risk. 

Biennial Screening "Cost-Effective" Amid Rising Demand

The Committee said that a large study had shown 2-yearly screening for people at lower risk was safe, and would be cost-effective amid rising demand for the service. The change, already in place elsewhere in the UK, was rolled out earlier this month  by the NHS in England, which said it would help them to "improve the service it offers by reducing the number of appointments people with diabetes at lower risk need to attend".

However, the Artificial Intelligence and Automated Retinal Image Analysis Systems (ARIAS) Research Group said it was "not clear what clinical and other impacts this change might have". So they undertook a large, real-world study, published online in the British Journal of Ophthalmology, which tracked the eye health of 82,782 people with diabetes in a North-East London screening programme. 

Participants were drawn from an ethnically diverse population — comprising 37% White, 36% South Asian, and 16% Black people — who had no diabetic eye disease in either eye on two previous consecutive screens between 2012 and 2021.

"Striking" Ethnic Differences in Retinopathy Prevalence

During up to 8 years' follow-up, retinopathy was detected more often among women than men, in the youngest (under 45) and oldest (65+) age groups, and among those with type 1 rather than type 2 diabetes. "Striking" ethnic differences emerged. Sight-threatening retinopathy was significantly more common among Black (hazard ratio 2.21, 95% CI, 1.93-2.53) and South Asian people (hazard ratio 1.54, 95% CI, 1.35-1.74) than among White people.

In addition, 1788 new cases of moderate to severe (sight-threatening) diabetic eye disease were picked up in people regarded as low risk, the researchers reported. Biennial screening would have delayed diagnosis by one year for more than half (1007 - 56.3%) of them. Furthermore, 103 patients had proliferative diabetic retinopathy, the most severe type, associated with late-stage damage that "requires urgent referral" and early treatment to stave off a very high risk of blindness. Biennial screening would have delayed diagnosis by one year for 45 of them (43.6%), according to the researchers. 

New Policy Risks "Critical Treatment Delays"

Introducing biennial as opposed to annual diabetic eye screening for people considered at low risk of diabetic retinopathy "could risk critical treatment delays and/or sight loss", the researchers warned, particularly among those at either end of the age spectrum and/or of Black ethnicity.

In a linked editorial, consultant ophthalmologists Dr Parul Desai, from Moorfields Eye Hospital in London, and Dr Samantha De Silva, from the Oxford Eye Hospital, said that the study "elegantly highlighted" the risk that health policy changes might "introduce unintended consequences". 

Given the evidence now available and the "significant change in service delivery that has either already taken place or is imminent", a review and update of the screening programme standards and their reporting requirements was "now overdue". This should introduce a requirement to report by age and ethnicity, with responsive action for unwarranted variation, as "one size may not always fit all".

Commenting to Medscape News UK, Dr Madina Kara, director of research and innovation at Fight for Sight / the Vision Foundation, said that regular screening for retinopathy was "imperative for accurate diagnosis and timely access to treatments". 

Risk of Preventable Sight Loss From Extending Screening Intervals

"Given the findings of this research, extending screening intervals risks further exacerbating health inequalities and leading to preventable sight loss," she said. Instead, she urged greater emphasis on increasing participation in screening programmes across different demographic groups "to ensure equitable chances of referral", particularly among communities at increased risk of poorer outcomes.

Dr Kara noted that the charity's report, Time to Focus, had estimated that reducing diabetic retinopathy prevalence by 1% each year could save the UK economy over £150 million by 2050.

AI Technologies Could Be Used to Maintain Annual Screening 

The researchers had pointed out that artificial intelligence (AI) technologies, which have "well-evidenced effectiveness" in reducing the human workload of grading retinal images, "could be used to assist in maintaining the current status quo in screening frequency". 

Such automated systems have been used in Scotland for over a decade, yet aren’t currently licensed for use in the English eye screening programme. Dr Kara also suggested "taking advantage of advances in the use of AI and machine learning in diagnostics" to benefit patients and help free up resources in the healthcare system.

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