Diabetic Eye Disease.
More than 1 million Australian adults have diabetes, and more than 1/3 of these have diabetic retinopathy. Diabetic retinopathy is the leading cause of preventable blindness in Australia.
Early detection and treatment of diabetic eye disease is critical in preventing severe and irreversible vision loss.
Diabetic eye disease
More than 1 million Australians have known diabetes.
There are 2 main types of diabetes:
Type 1 diabetes
This is an autoimmune condition whereby the immune system destroys the cells in the pancreas that produce insulin. It is not linked to lifestyle factors and cannot be prevented. It most commonly develops in children and young adults but can occur at any age.
Type 2 diabetes
This is a chronic condition whereby the body becomes resistant to insulin or loses the capacity to produce insulin in the pancreas. It is linked to lifestyle factors such as being overweight, unhealthy diet, lack of exercise and stress. It often runs in families. It most commonly develops in adults.
Diabetic eye disease most commonly affects the circulation at the back of the eye (the Retina). This is known as Diabetic Retinopathy. This is the most common and serious diabetic eye disease.
Other ways in which diabetes can affect the eye include:
1. Transient blurring of vision from changes in the blood glucose level
When the blood sugar levels are very high, this can cause temporary changes to the shape of the lens inside the eye. This will interfere with the focus of the eye, resulting in blurring of vision. This usually only lasts until the blood sugar levels are brought back to normal, either with diet or medication.
Cataracts are a normal aging process in the lens of the eye but occur more frequently and earlier in life in patients with diabetes.
Diabetes increases the risk of glaucoma, which can lead to progressive damage to the optic nerve in the eye, and slow but progressive visual loss.
Diabetic retinopathy is the leading cause of preventable blindness in working-age adults in Australia. More than 1 million Australians have known diabetes. More than 1/3 of these people (over 300,000) have diabetic retinopathy and about 65,000 have progressed to sight-threatening eye disease.
Yes, there are. You should:
- Control your blood glucose
- Control your blood pressure
- Control your cholesterol levels
- Make sure you are at your best weight and do regular exercise
- Quit smoking
Making sure you have regular follow-ups with your team of health professionals will help you achieve the above.
There are 2 main stages to DR, the early stage (before vision loss) and the sight-affecting stage (when vision loss occurs)
In the early stage, high blood glucose levels lead to damage of the small blood vessels at the back of the eye (the retina). The vessels become weak and may either leak clear fluid or become blocked. This is called “non-proliferative diabetic retinopathy” and does not usually affect the vision. So many diabetic patients will not know they have early stage DR unless they have regular eye checks.
In later stages, the damaged blood vessels in the retina will leak fluid onto the macula, known as “diabetic macular oedema”. This swelling of the macula leads to progressive loss of the detailed central vision.
The damaged blood vessels may also become blocked and lead to irreversible damage to the retinal nerves, particularly at the macula. Blockage of blood vessels results in a lack of oxygen supply to the retina (known as ischemia). Nature tries to fix this by growing new blood vessels, but these new blood vessels are abnormal and fragile and cause more harm than good because they also bleed and leak. This is known as “proliferative diabetic retinopathy” which can lead to many blinding complications at the back of the eye.
In the early stages of DR, you will not have any symptoms. In the sight-threatening stages of DR you may notice one or more of the following:
- Blurred or distorted or dimmed vision
- Dark spots or “hole” in your vision
- Difficulty seeing at night, increased light-sensitivity or haloes around lights
- Frequent changes in the prescription of your glasses or contact lenses
It is important to book a comprehensive eye exam with your ophthalmologist or optometrist to check for the early stages of DR or if you develop any of the above symptoms.
Dr Then will use several measures to diagnose diabetic retinopathy.
A vision check, eye pressure check and full dilated eye examination is performed, which will detect any early or sight-threatening stages of diabetic retinopathy at the back of the eye. This will also allow the diagnosis of other eye diseases which are more common in diabetics, such as cataracts and glaucoma.
Complementary testing using advanced technology is then performed, which helps to confirm the presence, location, severity and stage of any diabetic eye disease. This will help guide the treatment required.
1. OCT scanning. This is an ultra high-resolution scan of the retina that provides detailed images of the retinal layers. It is very useful in detecting and diagnosing diabetic macular edema, as well as monitoring the success of any eye injections used to treat it. Click here for more information on OCT scanning.
2. Fluorsecein angiography (FA). This involves the injection of a fluorescent dye into the bloodstream (normally through a vein in your arm) to highlight the blook vessels in the retina. Photographs are taken of this dye as it passes through the retinal circulation, and this will show any leakage or blockage of the retinal blood vessels. It will also show the growth of any abnormal new blood vessels (as seen in proliferative diabetic retinopathy). This will then help determine which treatment is required (eg eye injections and/or retinal laser).
3. OCT-angiography. This is a more recent technology which is a non-invasive way of looking at the blood vessels in the retina. It is a safer alternative to FA but does not yet provide as much information and detail as FA.
Yes there is. Early detection of DR is critical to slowing, halting or eve reversing the progression of any diabetic retinopathy, no matter what stage it is at.
Firstly, make sure you and your team of health professionals optimally manage your blood glucose levels, as well as your blood pressure and cholesterol levels. This requires regular check-ups and the use of diet and medication. Regular physical activity and quitting amoking are also very important.
If you develop sight-threatening diabetic retinopathy, there is also treatment which may halt or reduce the progression of the DR and vision loss:
1. Diabetic macular oedema:
If you develop swelling of the macula, the most effective treatment currently is a series of injections of a special medication into the back of the eye. There are 2 types of medications used, which are anti-VEGF drugs (EyleaR, LucentisR) or steroids. The choice of which one to use will depend on the location, severity and response to previous medications of the macula oedema and will be thoroughly discussed with you by Dr Then before commencing treatment.
In some cases, these injections may be augmented by focal or grid laser treatment to the macula, if required.
2. Proliferative diabetic retinopathy (PDR):
PDR is the most serious form of diabetic retinopathy. If it occurs, laser treatment to large areas of the peripheral retina are applied to halt its progression to blinding complications. This is known as Pan-Retinal-Photocoagulation (PRP) and is performed in the clinic under local anaesthesia. The purpose of this laser is to turn off the stimulus from the retina that leads to the growth of new (and abnormal) blood vessels in the retina, thus reducing the risk of complications such as bleeding into the gel of the eye (known as Vitreous Haemorrhage) or retinal detachment (known as Tractional Retinal Detachment).
If you develop these serious complications from PDR, you may require surgery to treat them, and this will best be performed by an ophthalmologist with expertise in these conditions, known as a retinal eye specialist. Dr Then has a network of retinal surgeons that she will refer her patients to if these complications develop.
Everyone with diabetes is at risk of developing diabetic eye disease. It is vital to regularly monitor for diabetic eye disease, as early detection and treatment of disease is critical in preventing severe and irreversible vision loss. The longer you have had diabetes, the more important it is to have regular eye tests, as the risk of eye disease is strongly related to the duration of your diabetes.
If you have diabetes, you should have your eyes checked by an ophthalmologist (eye specialist) or optometrist at least every 2 years. If you have additional risk factors for circulation problems (eg high blood pressure, high cholesterol, smoking) you should have your eyes checked every 12 months or more. If you have existing diabetic retinopathy, you may require eye checks more often than this.