New treatment strategies for diabetic eye disease

Argon laser treatment was the mainstay of treatment for diabetic retinopathy (DR) and maculopathy up to the last decade. However, with the better understanding of pathophysiology of DR, newer medications have become available. Anti-vascular endothelial growth factors (anti-VEGF) and steroid implants for vision-threatening diabetic macular oedema have been widely adopted in clinical practice with several longer-acting drug molecules in the pipeline. In the United Kingdom, ranibizumab and aflibercept are licensed anti-VEGF drugs. Dexamethasone and fluocinolone acetonide implants are the steroids that are available. The emphasis on systemic control of diabetes and blood pressure remains very relevant even in the era of these newer drugs.

Ophthalmic treatment of diabetic retinopathy

The ophthalmic treatment of diabetic retinopathy is aimed at preserving vision and requires an interdisciplinary approach. The main treatments used for proliferative retinopathy and diabetic maculopathy include laser photocoagulation, intra-vitreal, and peri-ocular drug injections, or a combination of both. In advanced cases of diabetic retinopathy (DR), vitrectomy and retinal surgery may help preserve vision. Cataract surgery in diabetic patients is extremely successful, but overall these patients are usually considered to be at risk of more complications than the general population. Those patients with pre-existing DR at the time of surgery should be regarded as a high risk group and will require careful pre-operative assessment and post-operative review. In this group, intervention with laser photocoagulation and intra-vitreal pharmacotherapy may be necessary.

Imaging in diabetic retinopathy

Imaging in diabetic retinopathy (DR) has developed over the years and the advantages are multifold. Various imaging modalities are currently available, which is of great diagnostic and prognostic value in the management of DR. Optical coherence tomography (OCT) has revolutionized the management of diabetic maculopathy. OCT has now become indispensable for initiating and assessing diabetic macular oedema (DMO) while on treatment with intravitreal injections. Recent introduction of optical coherence tomography angiography (OCTA) has significantly reduced the need for fundus fluorescein angiography (FFA) for macular ischaemia and proliferative retinopathy. Ultra-wide field (UWF) imaging modalities for colour fundus and UWF FFA are very useful to document and assess overall retinal state highlighting the periphery. Bscan ultrasonography of the fundus is an useful tool to assess retinal status in proliferative DR with vitreous haemorrhage.

Patients of concern

Some patients are of extra concern in diabetic retinopathy (DR) screening programmes. Failure to attend is a common problem and there are many reasons for this. Additional screening episodes may be required for medical reasons. The most commonly encountered situation is pregnancy, where special provision for screening services should be integrated into pre-conception and antenatal care. Rapid changes in glycaemic control may result in temporary deterioration in pre-existing retinopathy and, where possible, should be anticipated. This scenarios is likely to be seen more commonly with the availability of the insulin pump and bariatric surgery being considered more often. An aggravating effect of hypertension on DR needs to be recognized.

Training and accreditation for retinal screening and grading

In all national screening programmes, staff training to confirm competency and accreditation to practice in their profession is required for patient safety. This chapter sets out an example of how the UK diabetic eye programme has evolved in this respect. The current National Vocational Qualifications (NVQ) level 3: Health screener: diabetic eye screening for personnel undertaking screening and grading, will be explained. In some programmes, slit lamp examination is now provided by graders, as well as ophthalmologists and optometrists. The current requirement is detailed. In addition, all grading staff should also participate in test and training of retinal image sets in order to confirm accuracy of grading. At least 10 test sets should be undertaken per annum.

The screening episode: visual acuity, mydriasis, and digital photography

Early eye screening detection and treatment is fundamental in managing significant complications of chronic disease, both for improving diabetic retinopathy (DR) clinical outcomes and improving the economic burdens. Early detection and subsequent treatment can substantially reduce the risk of blindness from DR. This chapter will review the screening episode, measuring visual acuity, drop instillation, contraindications, and correct camera operation. It will review problems associated with incorrect camera operation and the NHS Diabetic Eye Screening Programme (NHSDESP) standards of acceptable image quality. This will guide the screener in obtaining clear, well-centred, gradable digital images of the retina in diabetic patients with vision better than no perception of light in both eyes, as well as providing a greater understanding of issues associated with screening.

Medical management of diabetic retinopathy

Medical management is focused on the proven benefit of tight glucose and blood pressure (BP) control. Standard management includes multiple cardiovascular risk factor management with angiotensin receptor blockade, statin, and fibrate treatment. Targets to achieve include HbA1c <7% (53 mmol/mol), BP <140/80, and serum cholesterol <4 mmol/L. A number of large recent trials have specifically demonstrated the beneficial effects on diabetic retinopathy (DR) of angiotensin receptor blockade (the DIRECT study) and fenofibrate (the fenofibrate intervention and event lowering in diabetes [FIELD] and action to control cardiovascular risk in diabetes [ACCORD] eye studies).

The principles of a national diabetic eye screening programme

Screening identifies apparently healthy people who may be at increased risk of a disease or condition, enabling earlier treatment or better-informed decisions. The NHS diabetic eye screening (DES) programme is one of the young person and adult NHS population screening programmes in the UK. The UK National Screening Committee (UK NSC), which makes independent, evidence-based recommendations to ministers in the four UK nations about the 11 population-based screening programmes. Public Health England (PHE)—Screening Quality Assurance Service (SQAS) ensures programmes are safe and effective by ensuring national standards are met.

How to grade

This chapter will provide guidance on best practice. A good grader should have the ability to work autonomously and have keen attention to detail; the grading environment should be quiet with appropriate lighting, and grading undertaken on high quality computer equipment and screens. All graders will adopt their own methodology for grading and use a step-by-step method, which may also use image manipulation. For accuracy and consistency, graders should adhere to minimum standards and numbers of grades as required by the NHS diabetic eye screening programme (NHSDESP). In the UK, graders should be adequately trained and participate in monthly test and training sets.

Background diabetic retinopathy

Background diabetic retinopathy (DR) can involve several different microvascular pathologies, which will be explained with example images. These include microaneurysms, haemorrhages, exudates, cotton wool spots, and venous loops. The reader will learn how these features relate to the grading and referral criteria. This chapter aims to provide information on how these pathologies develop and why it is important that they are recognized in the earlier stages of background DR. The chapter will demonstrate how ischaemia can affect the capillary network and also how related conditions, such as hypertension and blood glucose, can contribute to vascular changes. In addition, this chapter will explain how to differentiate normal variants from DR changes.