Diabetic retinopathy is the commonest cause of blindness in people under the age of 50 in Australia and second only to age-related macular degeneration in those over 50 years old.
Diabetic retinopathy is the damage caused by diabetes to the retina. It develops slowly and is often not noticeable to patients until very advanced. That is, serious sight threatening disease can develop without affecting sight. This is why regular annual (at least) examination of the retina is vital in all diabetics.
Very simplistically, small blood vessels such as capillaries are just like pipes in a garden irrigation system – they can either burst, leak or become blocked. Diabetic retinopathy is due to the effect of high blood sugar levels on the tiny blood vessels (capillaries) in the retina, causing them to bleed, leak or become blocked (ischaemia), and high blood pressure multiplies all of these effects. The damage seen in the retina is also occurring in the rest of the body but is simply not visible to doctors.
Diabetic retinopathy changes are classified into two main stages: proliferative and non-proliferative. Both can cause serious vision loss and ‘legal blindness’.
Diabetic Retinopathy – Dr Devinder Chauhan Vision Eye Institute
Dr Devinder Chauhan discuses what Diabetic Retinopathy is, and the most common treatments.
Visit us at: http://www.visioneyeinstitute.com.au/our-doctors/victoria/dr-devinder-chauhan/
Can Diabetic Retinopathy Be Cured?
It is important to understand that while vision can sometimes be improved by treatment, stabilising the retinopathy is the main goal of treatment. If the diabetic retinopathy is severe, then treatment may be mainly aimed at slowing its progress.
The three main treatments of diabetic retinopathy are laser photocoagulation, intravitreal injection of anti-VEGF drugs or steroids, and vitrectomy surgery. The choice and timing of treatment is dependent on many factors as well as the results of your tests.
How Is Diabetic Retinopathy Diagnosed?
Diagnosing the stage of retinopathy (non-proliferative or proliferative), as well as the need for treatment and frequency of monitoring, can only be made following a thorough examination of the retina after dilating the pupils of both eyes. In order to make decisions about the type and timing of treatment, it is often necessary to perform two other tests: optical coherence tomography (OCT) and fluorescein angiography (FA).
What Are The Signs And Symptoms Of Diabetic Retinopathy?
Diabetic retinopathy is the commonest cause of blindness in people of working age, but often causes no symptoms at all until very late in the process. This is why annual (at least) examination of the retina is extremely important in preventing vision loss.
When patients do have symptoms, they include blurring of vision, which may be variable, and seeing floaters. These can be spots, lines or clouds in their vision that develop quickly and appear to move around, particularly with eye movement. Diabetics should be seen urgently if any of these symptoms should develop.
What Are The Causes Of Diabetic Retinopathy?
Diabetic retinopathy is caused by high blood sugar levels, but is made worse by high blood pressure, high cholesterol and triglycerides, and smoking. All of these factors affect the amount of damage done to the tiny blood vessels (capillaries) throughout the body and how easily blood flows through them.
It has been shown without doubt that the tightest control of diabetes and blood pressure are equally important in preventing loss of vision. Diabetic smokers are at much higher risk of vision loss, heart attack, stroke and kidney failure; every effort should be made to stop.
What Is Non-proliferative (background) Retinopathy?
Non-proliferative diabetic retinopathy is the presence of small micro aneurysms (swelling of the capillaries) on the retina. This is an early sign that the small retinal blood vessels are being damaged. While the condition doesn’t usually affect vision, it’s vital that its progression is monitored. Treatment may be recommended to prevent non-proliferative retinopathy from developing into proliferative diabetic retinopathy.
What Is Non-proliferative Diabetic Retinopathy (npdr)?
In non-proliferative diabetic retinopathy (NPDR), the main risk to vision is through leakiness of the capillaries, which causes the retina to thicken. This is called diabetic macular edema (DME) and is ideally treated before vision is affected. In some parts of the retina, capillaries become blocked due to diabetes; this is called ischaemia. If these areas are small in total area, they may have no effect on vision and won’t need treatment.
The image above shows small blot-like haemorrhages as well as microaneurysms (red dots) that are small ballooned-out blood vessels that can leak. The image on the right is a lower magnification photo of a macula with exudates, fat that has leaked out of blood vessels very close to the centre of the macula. This is diabetic macular oedema and requires treatment to prevent further vision loss.
It generally takes at least 10 years of being diabetic before signs are visible in the retina. Poor diabetic and blood pressure control are the main reasons for progression from mild to moderate to severe non-proliferative diabetic retinopathy.
What Is Proliferative Diabetic Retinopathy?
In proliferative diabetic retinopathy (PDR), more vessels have been blocked off, making the areas of ischaemia larger. These, in turn, produce a chemical within the eye that causes abnormal new blood vessels to grow. While that seems a good idea, these new blood vessels don’t grow into the ischaemic retina, they grow into the vitreous. Movement of the vitreous and scarring may cause retinal detachment and bleeding into the vitreous (vitreous haemorrhage).
Often this happens without any noticeable vision changes until the last moment, but it is a very serious threat to sight. Urgent treatment may be needed, which may include laser, injections or vitrectomy surgery.
The image above is a colour photo and fluorescein angiogram of new blood vessels at the optic disc (NVD) and elsewhere (NVE), which are seen as bright patches where the fluorescein has leaked from them. Treatment is required to prevent serious visual loss.
Diabetes And Blood Pressure Control
Excellent diabetes control (HbA1C between 5.5 and 6.5%), normal blood pressure (130/80 mmHg or lower), and low blood cholesterol and triglycerides are the most important measures in the long term and are best treated by general practitioners, diabetes specialists (endocrinologists) and diabetes nurse educators.
The tightness of the control is absolutely vital – even small improvements can make a huge difference. For example, a reduction in HbA1c of just 1% drops a diabetic’s risk of severe visual loss in 5 years by 40%. Similarly, even a tiny drop in blood pressure from 130 /85mmHg to 130/80 can result in a 30% lower risk of severe visual loss.