Diabetes checks: delays in treatment are reduced when support staff assess eye images

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.

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.

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.


Study author

We were happy to see the graders performed well in reading back of the eye images and scans. Any graders who are unsure about an image or a scan need to be able to speak and discuss findings with an ophthalmologist. 

Based on the patient feedback we received in this study, we think it is important that patients receive results quickly, preferably on the day, about their condition. Patients need to know that they are still able to speak with an ophthalmologist from time to time. The intention of this work is not to cut off their contact with an ophthalmologist.

Noemi Lois, Wellcome-Wolfson Institute for Experimental Medicine, Queen’s University, Belfast, United Kingdom 

Diabetes UK 

Eye problems are a serious complication of diabetes and it is vital that they are treated early to ensure people have the best chance of a successful outcome. This interesting study explores whether a new pathway involving more junior eye specialists could be effective for treating and monitoring eye problems in people with diabetes. The research could inform future discussions around how eye problems are treated.

It’s promising that this pathway has the potential to be cost-effective and could help reduce waiting times, however it is essential that any changes to the current NHS pathway for treating eye problems also take into account the views of healthcare professionals and people living with diabetes.

Douglas Twenefour, Deputy Head of Care, Diabetes UK

Member of the public

My elderly mother has late-onset, type 2 diabetes, so I have a personal interest because I’d like to know what options might be available to her if her eye health declines. I’m also ‘horizon scanning’ for myself as I worry that I might be genetically predisposed to developing type 2 diabetes later in life – it is good to know about future innovations in healthcare assessment and provision that might be applicable.

This paper suggests that scans do not need to be read by ophthalmologists. Whether this is acceptable all depends on the level of training the person reading the scan has received. Reading scans is likely to be a highly specialised task. They would ideally have an understanding of the eye, vision and all related matters.

A Dennington-Price, Public Contributor, Norfolk 


Many units, including my own, are using virtual imaging clinics with the combination of OCT and UWF  images along with trained graders. This study adds to the evidence base that this is an effective and safe way to assess people with diabetic retinopathy. It also shows that graders who are not doctors can help deliver this service. Their accuracy is likely to improve over time with training and practice.

The paper therefore supports the current development of diagnostic imaging hubs to manage the increasing number of people with diabetes. Training pathways and clarification of who can be trained for such roles to enable enough graders to help will be important.

Graders could give people the results of their scans immediately, as the study suggests. However, results are likely to be more robust if done in a less rushed way and with the opportunity to double-check images where there is uncertainty. Giving results by telephone is another possibility. But people with diabetes are used to receiving screening results by letter and this may be the most practical approach.

James Talks, Consultant Ophthalmologist, Newcastle Upon Tyne Hospitals NHS Foundation Trust