Clinical context
Diabetes-related retinopathy (DR) occurs as a result of microvascular disease of the retina. It affects up to one in three people with diabetes, and can cause visual impairment and blindness.5 DR also impairs quality of life and ability to manage diabetes.6
Three distinct forms of DR are:
- macular oedema, which includes diffuse or focal vascular leakage within the macula
- DR caused by microvascular changes
- non-proliferative DR includes micro-aneurysms, intra-retinal haemorrhage, malformation and torturous vessels; may be asymptomatic
- proliferative DR – abnormal vessel growth on the optic disc or retina
- retinal capillary non-perfusion.
Sight-threatening DR includes:
- severe non-proliferative DR
- proliferative DR
- foveal-threatening diabetic macular oedema.
Non-proliferative DR affects 19.3% of people with diabetes, while 2.1% may have proliferative DR and 3.3% may have macular oedema.7 Proliferative DR and macular oedema are associated with elevated cardiovascular disease risk.8
In practice
Risk factors for the onset or progression of DR include:
- existing DR
- poor glycaemic control
- raised blood pressure
- duration of diabetes >10 years
- microalbuminuria
- dyslipidaemia
- anaemia
- pregnancy.
Visual impairment due to diabetes can be avoided for the vast majority of patients through good screening and care. This involves regular review of fundi, early detection and optimisation of therapy.
Monitoring for diabetic eye disease involves assessment of:
- changes in visual acuity (with correction)
- lens disease – for example, cataracts (refer below)
- fundal disease – for example, fundoscopy with dilation or retinal camera, or refer to an optometrist or ophthalmologist.
Screening methods and intervals for retinopathy are shown in Box 1.
Strategies for delaying the onset and progression of DR include:
- optimising blood glucose.9–11 Refer to the section ‘Glucose monitoring’ for suggested glycated haemoglobin (HbA1c) targets. Note that intensive glucose control in people with DR that is more severe than moderate non-proliferative DR on the International Clinical Diabetic Retinopathy Disease Severity Scale may not be beneficial12
- controlling blood pressure13
- adding fenofibrate – indicated for the reduction in the progression of DR in patients with type 2 diabetes who have existing DR. Fenofibrate does not replace controlling blood pressure, blood glucose and blood lipids as strategies to delay the progression of DR14,15
- ophthalmological specialist care
- laser therapy
- intraocular anti–vascular endothelial growth factor (VEGF) agents – ranibizumab, aflibercept and off-label use of bevacizumab (refer to the Pharmaceutical Benefits Scheme for further information)
- vitreo-retinal surgery.
KeepSight is a free online reminder system for people with diabetes about their next diabetes eye examination. It is managed by Diabetes Australia and Vision 2020.
The National Diabetes Services Scheme (NDSS) and Diabetes Australia send alerts and reminders to people with diabetes registered on the NDSS to have their eyes checked.
Box 1. Screening for retinopathy in type 2 diabetes
When to initiate screening3
Screening methods1
- Seven-standard field, stereoscopic-colour fundus photography with interpretation by a trained reader
- Direct ophthalmoscopy or indirect slit-lamp fundoscopy through dilated pupil
- Digital fundus photography
If retinopathy is present1,3
- Grade retinopathy severity, refer to ophthalmologist as appropriate, and establish appropriate monitoring intervals (≤1 year)
- Sight-threatening retinopathy may be treated with laser, pharmacological or surgical therapy*
- Review glycaemic, blood pressure and lipid control, and adjust therapy to reach targets as per guidelines
- Screen for other diabetes complications
If retinopathy is not present
Rescreen every year:3
- people with duration of diabetes >15 years
- suboptimal glycaemic control (HbA1c >8% or 64 mmol/mol)
- systemic disease – poorly controlled hypertension, lipids; other diabetes complications; foot ulcers
- Aboriginal and Torres Strait Islander people
- people from a non–English-speaking background
Rescreen every two years:3
- all other patients with type 2 diabetes
Review glycaemic, blood pressure and lipid control, and adjust therapy to reach targets as per guidelines
Screen for other diabetes complications
For more information, refer to the Royal Australian and New Zealand College of Ophthalmologists (RANZCO) screening and referral algorithm for diabetic retinopathy.
*Treatment options include fenofibrate, laser therapy, intra-ocular anti-VEGF agents, vitreoretinal surgery.
The role of retinal photography
Retinal photography is technically simple and is now usually performed within the Australian community by general practitioners, optometrists and ophthalmologists. Training is required to ensure quality of image interpretation.
Aboriginal health services are providing their own retinal photography services with support through telemedicine to promote access to screening.
People whose retinal images suggest they may be at increased risk of having, or at some point developing, sight-threatening retinopathy should be referred for assessment by an ophthalmologist.
Retinal photography may serve as a screening tool for retinopathy; however, it is not a substitute for a comprehensive eye exam.4
Note: A Medicare Benefits Schedule (MBS) item number for retinal photography with a non‑mydriatic retinal camera is available for general practice use.