Almost 1.1 million Australians have diagnosed (known) diabetes. In diabetics, the intermittent but long term increase in blood sugar level causes organs, especially the eye and kidney, to fail from blockage and leakage of blood vessels. Diabetes can lead to several problems in the eye, the most significant of which is diabetic retinopathy.
DIABETIC RETINOPATHY (DR) is the leading cause of preventable blindness among working age adults in Australia. Over 300,000 Australians have some degree of diabetic retinopathy, and about 65,000 have progressed to sight-threatening eye disease. The longer a person has diabetes, the greater their risk of developing diabetic retinopathy. DR affects the retina, or inner nerve lining, of the eye.
Screening for disease is important as early DR causes no symptoms but can lead to mild loss of vision initially, which then leads to moderate and severe vision loss and eventually blindness, if left untreated.
If you have been told you have diabetes, you should see an eye specialist (ophthalmologist) or an optometrist at least every two years for a comprehensive, dilated eye exam. People with diabetes with additional risk factors (eg high blood pressure, poor diabetes control), need to have an eye check at least every 12 months, even if vision appears to be perfect. Diabetics with existing diabetic retinopathy need to have an eye check every 6 to 12 months, even if vision appears to be perfect, or more frequently if disease is advanced. The longer you have had diabetes, the more important it is to have regular eye tests, even if the tests have always been clear in the past. This is because the risk of eye disease is strongly related to the duration of diabetes.
Diagnosis of diabetic retinopathy (DR) and diabetic macular oedema (DMO)
A full diabetic check does not need to be complicated. Most commonly, all that is required are eye drops to dilate your pupils and a microscopic examination of your eye by your eye specialist.
However, because early disease can be missed, a scan of the macula (like an X-ray, but without the harmful radiation) is sometimes performed. The scan reveals the internal structure of the macula, an important part of the eye vital for clear vision that can be damaged in diabetes.
Ultra Wide Field Imaging and Fluorescein Angiography
As well as OCT scans, because it is difficult to check the far periphery of your retina, ultra-widefield (UWF) photography is often required. This frequently reveals early disease when none is found with a clinical examination. Furthermore, what seems mild disease is sometimes found to be worse when the full retina is examined in this way. This can lead to early preventive treatment or, alternatively, simply flag the need to improve glucose control to avoid further deterioration. Sometimes, new problems unrelated to diabetes, are found that would otherwise have been missed.
When required, UWF fluorescein angiography is performed which can reveal imminent problems in the eye, such as poor blood supply or early leakage from diseased blood vessels. Angiography involves the injection of a light reactive dye into the veins which show up on special photographs. Early preventive treatment can often be started which avoids more complicated therapy when these tests detect early signs of problems. Use of a UWF camera increases the chance of finding early or unsuspected disease.
TREATMENT Early diagnosis is essential so that treatment can be started early, which can prevent or reverse loss of vision. Most people with diabetic retinopathy should keep most, if not all vision, providing it is diagnosed early and all steps are taken to keep it under control. When required, treatment may be given with laser or injections.
Traditional laser treatment, known as laser retinal photocoagulation, though effective, is used less frequently nowadays because new drugs that work inside the eye are better at ensuring vision is not not lost and maintained to a high level for a long time. In some circumstances, focal laser photocoagulation can be useful when directed away from the macular area at specific points of leakage from diseased blood vessels. In this situation, laser treatment prevents the spread of fluid into the macular area where it can result in vision loss.
In advanced diabetic retinopathy, new blood vessels can grow into the retina and because they are diseased vessels, they can bleed into the eye causing severe vision loss. If these new vessels are seen, a form of laser known as panretinal photocoagulation can be applied to cause the new vessels to shrink away and disappear.
However, a new laser known as 2RT has been shown to be be as efficacious but safer in patients with CSME compared to traditional laser retinal photocoagulation. While laser retinal photocoagulation is effective at treating CSME, maintaining vision and reducing macular swelling, the treatment results in collateral damage to the parts of the retina crucial to vision. 2RT is capable of achieving the same degree of clinical efficacy as conventional laser retinal photocoagulation but without damage to the overlying neurosensory retina (specifically, no damage is caused to the photoreceptors or light receiving cells of the retina). 2RT rejuvenates the aged, compromised retinal pigment epithelium (RPE) – a laser of support cells in the retina, without damage to the overlying neurosensory retina (specifically, no damage is caused to the photoreceptors). Click the button to read about 2RT:
When the centre of the retina - a part of the eye known as the macula - becomes swollen, injections of a drug from the antiVEGF family can reduce or eliminate the swelling resulting in improved vision. To get these drugs into the eye, an injection is given with a tiny needle. An anaesthetic is given before the injection. Very little, if any, pain should be experienced during the procedure. It is a quick procedure and usually occurs in the clinic.