About a third of people with diabetes will develop retinopathy, and it will be severe enough to threaten vision in one of three of them, says Professor Richard O’Brien, endocrinologist and Clinical Dean of Medicine at the University of Melbourne.

But early detection and aggressive management of risk factors such as glycaemic control, hypertension and hyperlipidaemia can change this trajectory.

A quick refresher

In diabetic retinopathy, chronic hyperglycaemia damages capillaries inside the retina and leaves its microvasculature more susceptible to further injury from systemic hypertension.

Diabetic retinopathy can be classified according to three types: non-proliferative, proliferative, and macular oedema. A progressive disorder, the non-proliferative type increases in severity until it becomes proliferative, with macular oedema occurring at any point in the disease process.

The earliest noticeable change involves the formation of micro-aneurysms, which are seen in most people with chronic diabetes, Professor O’Brien says. Blocked and leaky microvasculature leads to dot, blot or flame haemorrhages.

Screening key to detection

In its early stages diabetic retinopathy rarely causes symptoms, so screening is crucial.

“Vision stays normal, and people do not know that they are developing problems,” Professor O’Brien says. “Later on, things like floaters, blurred vision, perhaps changes in colour vision can be a sign, but you would hope that we would have identified the problem long before these symptoms develop.”

Most guidelines recommend a comprehensive eye examination at diagnosis and then two-yearly, he says. High risk patients, including Indigenous Australians, should have an annual assessment. People with established retinopathy may need more frequent assessments, he adds.

Direct ophthalmoscopy is not sufficient, Professor O’Brien says.

“We need to have proper eye examinations done by people who are expert in the area, generally with either retinal cameras or with things like slit lamps that optometrists or ophthalmologists use.”

Improving screening rates

Despite the importance of screening, approximately one in five non-Indigenous Australians with diabetes – and almost one in two Indigenous Australians with diabetes – are not having eye examinations at the recommended frequency, including a proportion who have never been screened at all.

“We really need to do as much as we can to encourage our patients to get tested,” Professor O’Brien says.

One option is to register patients with the free KeepSight program, which sends reminder alerts encouraging people registered with the National Diabetes Services Scheme to have a diabetes eye check.

GPs with appropriate training can consider in-house retinal photography, especially in rural and remote areas. Professor O’Brien says the non-mydriatic camera is reasonably priced and practice nurses can be trained to use it, with Medicare item numbers associated with this examination.