The “blinding” effect of diabetes on the eye
What is diabetic retinopathy ?
The retina lines the inside of the eye and acts rather like the film in a camera. The macula is the small central part of the retina that you use to see things clearly and is the part you are using now to read. You use the rest of your retina to see things around you and to see in the dark.
Blood vessels bring oxygen and nourishment to your retina. These blood vessels may be damaged in a number of ways if you have diabetes. Severe changes to the retinal blood vessels will affect the health of your retina and this can damage your sight.
Why is diabetic retinopathy important ?
Who gets diabetic retinopathy ?
All people with diabetes are at some risk of getting diabetic retinopathy. This is true whether your diabetes is controlled by diet, tablets or insulin.
You are at greater risk if :
What does diabetic retinopathy look like ?
The earliest changes are called background retinopathy. Small changes develop on the blood vessels and look like tiny red dots. These are called microaneurysms. Larger red dots are called retinal haemorrhages. They lie within the retina and are very like a bruise on your skin. Background retinopathy does not affect your sight and does not need treatment. However, you should make sure that you go for screening every year and control your diabetes well.
As time goes by, your blood vessels may become constricted and the retina may become starved of oxygen and nutrition. Different signs can be seen in the retina at different stages during this progression. These are called pre-proliferative retinopathy and requires more frequent follow ups.
Eventually you may develop new blood vessels on the retina. This is called proliferative diabetic retinopathy. At this stage your sight is at risk as the vessels may bleed or may develop scar tissue. This can pull the retina away from the underlying layers of the eye, causing a traction retinal detachment. If the new vessels bleed, you may see a sudden shower of floaters or cobwebs in your sight, or your sight may be completely blurred. This is called a vitreous haemorrhage.
If you develop proliferative retinopathy or if you are very close to developing proliferative retinopathy, you will be advised to have laser treatment.
You may also suffer from changes in the blood vessels at the macula. The commonest change is that the blood vessels become leaky. Fats and fluid that are normally carried along in the bloodstream may then leak into the macula. Fats that have leaked into the retina are called exudates. Fluid leaking causes waterlogging in the retina and is called “oedema”.
Oedema at the centre of the macula ( Diabetic Maculopathy or Macular Oedema ) will cause you to lose some sight and you may need gentle laser treatment or an injection in the back part of the eye ( Intravitreal Triamcinolone , Intravitreal Anti VEGF or Macugen)
How will I know if I have diabetic retinopathy ?
Diabetic retinopathy does not usually cause a loss of sight until it has reached an advanced stage. Even sight-threatening retinopathy that is close to affecting your sight may not cause symptoms.
Diabetic retinopathy is best detected by examining the back of your eyes to look at your retina as a part of routine screening yearly or more frequently as outlined above.This is done by indirect ophthalmoscopic examination and slit lamp biomicroscopy. When required photographic documentation, retinal angiography, scanning of the retina (OCT), sonography has to be done to know the disease severity and plan the management accordingly.
You must seek urgent retina evaluation if
Do’s and don’ts
Diabetic retinopathy can get worse over time, but the following measures can help you to reduce your risks of developing diabetic retinopathy and to slow the progress of sight-threatening retinopathy.