Published: 25 October 2023
Extending the annual screen to two years for people in England considered at low risk of diabetic eye disease could lead to critical treatment delays and sight loss. This is according to research led by researchers at St George’s, University of London and published in the British Journal of Ophthalmology.
Diabetic eye disease is when the delicate network of tiny blood vessels at the back of the eye becomes damaged, and early treatment is vital to stave off blindness.
Researchers found that a two-yearly screen delayed hospital referral by 12 months in half of those who developed serious diabetic eye disease, with those at either end of the age spectrum and of Black ethnicity most at risk.
The NHS introduced an eye screen (DESP) in 2003 for people in England with types 1 or 2 diabetes from the age of 12 onwards, with the aim of picking-up diabetic eye disease.
National screening needs review
Since 2016, the UK National Screening Committee has recommended annual eye checks for those at high risk of sight loss, and two-yearly checks for those considered to be at low risk in light of evidence indicating that this interval is safe and cost effective amid rising demand for the service.
Already in place elsewhere in the UK, it is now being implemented in England. But it’s not clear what clinical and other impacts this change might have, say the researchers. To plug this knowledge gap, they drew on one of the largest and most ethnically diverse diabetic screening programmes in North East London.
Analysed over 82,000 people
The team tracked the eye health of 82,782 people with diabetes but with no diabetic eye disease in either eye on two previous consecutive screens between 2012 and 2021. Over a third were of White (36%) or of South Asian (37%) ethnicities, and 16% were Black.
Over 8 years, they looked at the numbers of people who developed the condition, and the implications of potential delays in referral for treatment as a consequence of an eye check every two years instead of one.
During this period, 1,788 new cases of moderate to severe (sight threatening) diabetic eye disease were picked up in people regarded as being at low risk. Of these, 103 cases had the proliferative form (PDR) - the most severe type associated with late-stage damage that carries a very high and short-term risk of blindness which requires urgent referral.
Men had lower rates of sight threatening diabetic eye disease than women, and those with type 1 diabetes had higher rates than people with type 2 diabetes. There was no clear pattern across levels of deprivation.
Striking ethnic differences
However, striking ethnic differences emerged over time. Case rates were significantly higher among Black people, who were 121% more likely to develop sight threatening diabetic eye disease than White people, while South Asian people were 54% more likely to do so.
Based on these figures, extending the annual eye check to two years would have delayed diagnosis by 12 months in more than half (56.5%) of those with sight threatening disease and in nearly half (44%) of those with PDR.
The diagnostic delays stratified by ethnic group were 256/30,350 among White people, 379/29,730 among South Asian people, and 256/13,391 among Black people - equivalent to 844, 1276, and 1904 per 100,000 screened, for each ethnic group, respectively.
For PDR, numbers were much lower, but rates were still higher among Black people (90/100,000) compared with White people (46/100,000).
Young and old most impacted
Progression to sight threatening diabetic eye disease was also more pronounced in the youngest (under 45) and oldest (65+) than it was for those in their mid-40s to 60s.
Diagnostic delays stratified by age were highest among the under 45s (1,504 per 100,000 screened) and among those aged 65 and older (1248 per 100,000), compared to 45 to 54 year-olds (1,178 per 100,000) and among 55 to 64 year-olds (987 per 100,000).
Need to address healthcare inequalities
“Our work highlights that one policy doesn’t fit all when it comes to diabetic eye screening. The national implementation of a two-year wait, instead of every year, in those deemed at ‘low-risk’ of diabetic eye disease does not affect all population sub-groups equally.
“Younger people and people of black and Asian ethnicities are most affected by delays in the detection and referral of the most serious eye disease. This needs to be addressed to avoid inequalities in eye healthcare.”
- Professor Christopher Owen, Professor of Epidemiology in St George's Population Health Research Institute -
The researchers – from St George’s, Homerton Healthcare NHS Foundation Trust, Moorfields Eye Hospital NHS Foundation Trust, UCL and Kingston University – suggest that artificial intelligence technologies could be used to assist in maintaining the current status quo in screening frequency. But despite their well evidenced effectiveness in reducing the human workload of grading retinal images for diabetic eye disease, automated systems, which have been used in Scotland for over a decade, aren’t currently licensed for use in the English NHS DESP.
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