Disease of the retina (the light-sensitive layers at the back of the eye which enable us to see) occurs more often in people who have had diabetes for a long time, who are taking insulin, or whose diabetes is not controlled very well.
When a person is diagnosed with diabetes, it isn't possible to predict at the time whether or not he or she will get retinal disease. However, about two-thirds of people with juvenile-onset diabetes (type 1 diabetes) will develop some significant retinal disease by 35 years after they've been diagnosed. One-third will develop swelling in their central area of vision. This is known as macular oedema. The retinal disease is called Diabetic Retinopathy.
The longer a person has diabetes, the more likely the person is to develop diabetic retinopathy.
In the early stages of diabetic retinopathy there are no symptoms and vision may not change
until the disease is advanced. There are two forms of retinopathy that can affect sight:
Maculopathy - develops when some of the small blood vessels around the macula (the part of the retina that provides sharp, central vision) become blocked. This causes other blood vessels to leak, so that fluids build up around the macula causing swelling and loss of sight.
Proliferative retinopathy - develops when abnormal blood vessels grow in the wrong places on the surface of the retina, and even forward into the centre of the eye. These blood vessels bleed easily, blocking vision. As they heal, scar tissue forms, resulting in a tightening that can pull on the retina and may cause it to separate from the back of the eye. This causes vision loss.
retina showing proliferative retinopathy
(v) growth of new unnatural blood vessels
(h) retinal haemorrhage
Diagnosis of Retinopathy
Diabetic retinopathy can be detected during a comprehensive eye examination through dilated (enlarged) pupils. An eye specialist uses medicated drops to enlarge the pupil. The enlarged pupil makes it easier to examine the back of the eye and detect early signs of the disease.
Diabetic retinopathy can also be detected with a special camera that can photograph
the back of the eye without the use of dilating drops. Although this method checks for signs of
diabetic retinopathy, it is not a comprehensive eye examination.
People with diabetes should have their eyes examined for diabetic retinopathy when diabetes is diagnosed, and then at least every two years. When changes are noticed in the retina more frequent examinations are recommended.
Treatment of Retinopathy
Laser treatment is used successfully to treat retinopathy. A narrow, high energy light beam is aimed through the pupil and onto the retina to shrink the abnormal blood vessels. However, laser treatment cannot restore vision that has already been lost.
Where to get help:
- Your family doctor
- Ophthalmologist (eye specialist)
Things to remember
Everyone with diabetes can eventually develop diabetic retinopathy.
Vision loss or blindness is preventable through early detection and timely treatment.
Good control of diabetes and regular eye examinations (at least once every two years) can prevent vision loss.
It is important to take action before you notice any eye problems.
A cataract is cloudiness in the lens of the eye and it leads to vision loss. Cataracts are more common in people with diabetes than the rest of the population and may also occur at an earlier age in people with diabetes than others.
Cataract surgery usually has good results. It often involves removal of the lens of your eye which is replaced with a synthetic lens implant.
Doctors estimate that about 10 per cent of people with diabetes over the age of 40 have open-angle
glaucoma, which is a condition where increased pressure within the eye causes damage to the optic nerve and so impairs vision or causes blindness. This compares to a figure of 3.3 per cent of people over the age of 40 who don't have diabetes. For more information on Glaucoma and how it is treated go here.
General Diagnosis and treatment
Good control of diabetes is the best way of preventing complications.
Having your eyes checked regularly by a doctor is the most effective way of detecting any damage to your eyes. This should be at least every year if you are taking insulin, and every 2 years if you are not. However, if you are getting symptoms like blurred vision, especially if this comes on suddenly, then see a doctor without delay.
Additional risk factors
If you have other vascular diseases such as high blood pressure (hypertension), these should be treated as they can increase the damage to the eye in people with diabetes. Kidney disease also makes eye damage worse, particularly if you have high blood pressure as well. If you are pregnant, good control of diabetes is vital for both you and your baby.
If you smoke, you should definitely stop. Nicotine constricts blood vessels, which can be harmful to a person with diabetes. In addition, doctors believe smoking undoes the good work that good blood sugar control has on the blood vessels. Talk to your doctor about giving up now. There are many methods available to help you.
The good news is that with regular eye checks and following your doctor's recommendations, blindness from diabetes can be reduced just as effectively as it has been from other diseases such as trachoma, river blindness and vitamin A deficiency.