29th December 2023

Diabetic retinopathy

Background

Diabetic retinopathy (DR) is the most common sight-threatening retinal vascular disease and is one of the leading causes of visual impairment in the working-age population. Risk factors for the development of diabetic retinopathy include a longer duration of diabetes, hyperglycaemia, hypertension, hyperlipidaemia, pregnancy, and renal disease.

The National Institute of Health and Care Excellence (NICE) recommends that all adult patients with diabetes should be referred to the local community diabetic retinopathy screening service at the point of diagnosis and should continue to be screened at least once a year. These patients are then referred to the hospital eye services if they develop sight-threatening retinopathy.

Clinical Features

Diabetic retinopathy can be categorised into the ‘non-proliferative’ and ‘proliferative’ stages.

Patients tend to be asymptomatic until they develop maculopathy (blurred central vision), proliferative retinopathy with vitreous haemorrhage, or fibrovascular proliferation, which may develop into tractional retinal detachment (floaters, blurred vision).

There are various classification systems used for diabetic retinopathy. The following grading system is used by the Diabetic Screening Programme and is based on the UK National Screening Committee (NSC) criteria:

Complications

People with proliferative diabetic retinopathy may develop vitreous haemorrhage and tractional retinal detachments, which may require surgery. Other causes of visual loss include macular ischaemia and neovascular glaucoma.

People with low vision due to diabetic retinopathy (or other common causes such as glaucoma and age-related macular degeneration) can develop Charles Bonnet syndrome, a condition in which they experience visual hallucinations but retain insight that their hallucinations are not real.

Management

Systemic Management: 

Blood pressure and glycaemic control should be optimised for all patients. Patients should be assessed and treated for dyslipidaemia, particularly if significant macular exudation is present.

Ocular Management: 

Non-proliferative diabetic retinopathy should be closely monitored at appropriate intervals depending on the stage of retinopathy.

For patients with proliferative diabetic retinopathy, urgent pan-retinal photocoagulation should be considered, particularly if there are high-risk features such as vitreous haemorrhage, new vessels on the disc >1/3 disc diameter in size, or new vessels elsewhere on the retina associated with vitreous haemorrhage.

For patients with diabetic maculopathy, management depends on the extent and location of macular oedema. Non-centre involving macular oedema is asymptomatic and can be observed; alternatively, macular laser can be considered in discussion with the patient. Intravitreal anti-vascular endothelial growth factor (anti-VEGF) injections such as Ranibizumab (Lucentis) are licensed for the treatment of diabetic macular oedema if the central retinal thickness is 400 microns. Aflibercept (Eylea) is another option. Intravitreal steroid implants such as Ozurdex can be used for pseudophakic patients. Intravitreal injections carry a low (0.024-0.265%) risk of acute postoperative endophthalmitis, which can have a devastating impact on the patient’s vision and, hence, quality of life. Clinicians should, therefore, have a low threshold of suspicion in patients presenting with loss of vision and/or severe eye pain after injections.

Image Source: Wikimedia Commons (2006). Fundus photo showing focal laser surgery for diabetic retinopathy EDA10, Licensed under a creative commons licence. Available for free at: https://commons.wikimedia.org/wiki/File:Fundus_photo_showing_focal_laser_surgery_for_diabetic_retinopathy_EDA10.JPG  (Accessed on: 18 June 2022).

Image Source: Wikimedia Commons (2006). Fundus Proliferative retinopathy EDA01, Licensed under a creative commons licence. Available for free at: https://commons.wikimedia.org/wiki/File:Fundus_Proliferative_retinopathy_EDA01.JPG (Accessed on: 18 June 2022).

Image Source: Wikimedia Commons (2006). Fundus photo showing scatter laser surgery for diabetic retinopathy EDA09, Licensed under a creative commons licence. Available for free at: https://commons.wikimedia.org/wiki/File:Fundus_photo_showing_scatter_laser_surgery_for_diabetic_retinopathy_EDA09.JPG (Accessed on: 18 June 2022).