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This is a plain English summary of an original research article. The views expressed are those of the author(s) and reviewer(s) at the time of publication.

People living with diabetes need regular eye examinations to prevent serious problems with their vision. A shortage of eye specialists (ophthalmologists) is leading to delays in appointments. New research suggests that support staff could be trained to read images of the back of the eye (retina) almost as well as ophthalmologists. 

Most of the support staff in the study were specialist photographers who normally take images of the retina (ophthalmic photographers). The research suggests that they could be trained as ophthalmic graders and take on a new role in the NHS. They could increase capacity and reduce delays in people’s eye assessments.  

Diabetes and its complications are becoming increasingly common. The medical charity Diabetes UK estimates that 30 people per week have their sight seriously affected by the condition. People with diabetes need to be seen in a timely manner. Early treatment is more likely to prevent serious eye problems, including sight loss.

The COVID-19 pandemic has added to delays in eye examinations. By training graders to read scans of the retina, this research suggests that more people can be monitored and more visual problems prevented.  

More information about this complication of diabetes (diabetic retinopathy) is available on the NHS website

What’s the issue?

Diabetes is a life-long condition affecting more than 4.9 million people in the UK. It is becoming increasingly common, and a further 13.6 million people are at risk of developing it

People with diabetes have high levels of sugar in the blood. It can lead to damage of the tissue at the back of the eye (the retina), which detects light. This condition is called diabetic retinopathy. 

Some people with diabetic retinopathy have damaged blood vessels which leak and make the centre of the retina (the macula) swell. This is called diabetic macular oedema (DMO). In other people, fragile new blood vessels grow and might bleed or scar, detaching the retina. This is proliferative diabetic retinopathy (PDR). Both conditions can cause blindness if not diagnosed and treated quickly.

People with diabetes are offered annual eye screening from the age of 12 onwards to detect these conditions. Treatments include laser therapy, eye surgery or injections of drugs called anti-VEGF into the eye.

After successful treatment, people need regular eye examinations, initially every month. This is because their condition could return. Growing numbers of people need this follow-up. But the numbers of ophthalmologists have not increased to meet this demand. This means that people with diabetes face delays in receiving treatment, which could result in visual problems and even blindness.

A new study explored whether support staff who are not doctors could be trained as ‘graders’ to examine images of the retina. Most of the graders in the study were specialist photographers with experience of taking and looking at scans. They received training and were then monitored to see if they could assess eye scans as accurately as ophthalmologists. 

The study also looked at the cost-effectiveness and acceptability of the new approach using graders. The new pathway could take some patients off ophthalmology waiting lists, cut delays and allow more people to be checked.

What’s new?

The study was carried out in 13 NHS hospitals in England, Scotland and Northern Ireland. It was called EMERALD (Effectiveness of Multimodal Imaging for the Evaluation of Retinal Oedema and New Vessels in Diabetic Retinopathy). 

The non-specialists received two days’ face-to-face training, and two half-day webinars, on the features of diabetic retinopathy. They could consolidate their knowledge in a web-based teaching programme which provided more examples. They were given clear guidelines on when to refer patients to ophthalmologists.

EMERALD included 397 people with diabetes who had all been successfully treated for either condition in one or both eyes. They were separated into two groups according to their diagnosis (DMO or PDR).

All participants had a standard check-up: a face-to-face appointment with an ophthalmologist and an OCT scan. The ophthalmologist identified people whose eye conditions had returned. The participants also received enhanced care: they had a further two images taken (7 field-ETDRS and UWF). These images can show the growth of new blood vessels (sometimes missed in standard check-ups). 

Neither graders nor ophthalmologists in the study knew the results of the face-to-face check-up. Both groups looked at the images (OCT, 7-field ETDRS and UWF) and the researchers compared graders’ and ophthalmologists’ assessments. 

The study found that graders could read images of diabetic retinopathy almost as accurately as ophthalmologists. 

For people with a DMO diagnosis, graders:

  • correctly identified almost all (97%) cases of DMO 
  • were less able to rule out the disease when it was not present; they referred two in three (69%) scans which did not have macular oedema to the ophthalmologist.

For people with a PDR diagnosis, graders:

  • correctly identified most cases of PDR (85% with ETDRS; 83% with UWF scans) 
  • were again less able to rule out the disease when it was not present; they referred around one in two scans which did not have PDR to the ophthalmologist (52% of ETDRS; 46% of the UWF scans).

Graders were more accurate when assessing images of high-risk PDR.

The researchers looked at the acceptability of the new pathway. Focus groups in Northern Ireland, Scotland and England included 36 people from the study. They said their preference was for face-to-face examinations by ophthalmologists, to discuss their eye condition, ask questions and receive reassurance.

However, they would accept a grader’s assessment if an appointment with an ophthalmologist was not available. In that case, people wanted immediate results. They also wanted occasional appointments with ophthalmologists, even if at longer intervals. Both ophthalmologists and graders supported the new pathway, but graders warned that they may not be able to answer all questions from people with diabetes. 

This study found that using graders to assess images could save ophthalmologists’ time and be cheaper to deliver. Using graders could save £1390 per 100 visits for DMO. It would save slightly less, between £461 - £1189 per 100 visits for PDR. The graders referred many scans (with no diabetic retinopathy) to ophthalmologists, but the approach still saved money. 

Why is this important?

Commissioners may be interested in these findings. A shortage of ophthalmologists is causing delays in routine eye checks for people with diabetes. Training more graders to read eye scans and images of the retina could reduce waiting times.

The graders in this study picked up most cases of diabetic retinopathy. The approach was safe because graders sent images to be checked by ophthalmologists whenever they thought there might be disease (even if there often was not). Despite the number of images referred to the ophthalmologist, the new pathway still made savings compared with an ophthalmologist seeing patients in clinic.

In the study, graders could not see scans from people’s previous visits to the clinic. In practice, they would have access to more information, and this could improve their accuracy further. 

What’s next?

Graders could run clinics, which people attend for eye scans only, rather than having a full consultation with an ophthalmologist. These grader clinics might be most suitable for some groups of people, for example those with more stable disease. This group of people could still see an ophthalmologist from time to time, which was seen as important by participants in this study. 

The researchers recommend that grader clinics could be held side by side with ophthalmologist clinics. This would allow graders to ask ophthalmologists questions when they are uncertain, which would give an immediate answer. This could reduce the number of images sent for a second opinion. 

Focus groups in the study suggest that staff members and their roles need to be carefully introduced in clinics. People with diabetes would find it reassuring to be clear on staff members’ expertise and level of training.

Several study sites are now using this new grader pathway. It is reducing waiting times and freeing up ophthalmologists to focus on people with more severe disease. One site had used a similar pathway for some years. This study provided backing, and more graders are being trained as a result.  

The Royal College of Ophthalmologists is reviewing the guidelines for managing diabetic retinopathy and the researchers hope that the use of graders will be recommended. 

EMERALD could also serve as an example of training non-medical support staff to carry out other specific tasks. It could apply to other areas of healthcare.

You may be interested to read

This NIHR Alert was based on: Lois N, and others. Evaluation of a new model of care for people with complications of diabetic retinopathy. American Academy of Ophthalmology 2021;128:561-573.

A recent paper exploring the acceptability of virtual clinics and new care pathways: Prior L and Lois N, on behalf of the EMERALD study group. Patients views on a new surveillance pathway involving allied non-medical staff for people with treated diabetic macular oedema and proliferative diabetic retinopathy. Eye 2022; doi:10.1038/s41433-022-02050-1

For more information around diabetes, visit Diabetes UK, the leading charity for people living with diabetes in the UK.  

Funding: The EMERALD study was funded by the NIHR Health Technology Assessment programme

Conflicts of Interest: The study authors declare no conflicts of interest.

Disclaimer: NIHR Alerts are not a substitute for professional medical advice. They provide information about research which is funded or supported by the NIHR. Please note that views expressed in NIHR Alerts are those of the author(s) and reviewer(s) and not necessarily those of the NHS, the NIHR or the Department of Health and Social Care.

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Information about the scans

Slit-lamp biomicroscopy: an ophthalmologist puts drops into the eye to enlarge (or dilate) the pupil. After around 20 minutes, the ophthalmologist will examine their eyes. This is part of the standard consultation with an ophthalmologist.

OCT: this stands for optical coherence tomography. An OCT scan uses light waves to capture images of the retina.

ETDRS: this stands for Early Treatment Diabetic Retinopathy Study. In EMERALD, seven images were used (it is called 7-ETDRS). People are asked to look in seven different directions and an image is taken of each view.

UWF: This stands for ultra-widefield. UWF cameras capture almost the entire retina in a single image.

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