Feasibility of an Alternative Pathway for Hospital Referrals From Diabetic Eye Screening Wales (DESW) for People Suspected With Sight-threatening Diabetic Eye Disease Diabetic Maculopathy (FARSight-DM)

1 Background Diabetes mellitus, as estimated by the International Diabetes Federation (IDF), affects 537 mil-lion people globally which is expected to increase to 783 million by 2045. DED is amongst the commonest and most feared complications of diabetes consisting of diabetic retinopathy and diabetic macular oedema. In 2020, world-wide, 103 million people were estimated to have DED, 15 million with vision threatening DED and 29 million having diabetic macular oedema, projected to reach 161 million, 45 million and 77 million respectively by 2045.

Until recently, DED has been the leading cause of blindness (Severe Sight Impairment, SSI) in the working age population in developed countries. However, since the introduction of screening for DED in the UK, along with improvements in diabetes and ophthalmological care, DED is no longer the leading cause of SSI in the UK. In Wales, new certifications for both sight impairment (SI) and SSI have fallen by 50% since screening commenced.

Screening for DED in Wales is performed by the DESW, utilising digital photography performed by trained photographers and the images are graded by trained readers, utilising standardised protocols and quality assurance. All cases of sight-threatening diabetic retinopathy (DR) i.e., severe pre-proliferative DR, proliferative DR and diabetic maculopathy require referral to ophthalmology for review and/or treatment. However, 2-dimensional (2-D) digital photography used by DESW, whilst adequate for assessing diabetic retinopathy lesions, cannot determine the presence of diabetic macular oedema (increased retinal thickness). Current screening uses surrogate markers for suspecting the presence of maculopathy such as exudates within 1 disc diameter of the fovea or microaneurysms and haemorrhages with an unexplained visual acuity of 6/12 or worse. Diagnosing diabetic maculopathy requires a 3-D camera using OCT technology to determine whether treatment or monitoring is required. On OCT imaging, a substantial number with suspected diabetic maculopathy do not have maculopathy and are either dis-charged back to DESW or remain under monitoring for years in HES without ever having treatment.

Many HES departments experience lack of specialists and available space to cope with the ever-increasing patient numbers, which has led to significant delays in treatment and in some cases irreversible SSI. Therefore, there is a need to consider new ways of conducting ophthalmology services and to allocate certain elements into the primary care sector. Examples already exist such as the national Eye Health Examinations Wales (EHEW) service, and the national low Vision Service Wales. Increasingly, Health Boards are developing locally enhanced primary eye care pathways in partnership with the HES, such as Ophthalmic Diagnostic and Treatment Centres for glaucoma and age-related macular degeneration. In some parts of England, OCT surveillance clinics have been incorporated into diabetic eye screening, requiring additional funding. Currently, due to the increasing workload and Covid-19 related disruption, DESW cannot take on this extra work.

The Covid-19 pandemic made pre-existing pressures on the HES more evident and whilst services are returning to normal, the backlog and pressure from the numbers of new patients make it extremely difficult for the already stretched HES and DESW to continue seeing patients and to catch up.