What Causes Diabetic Retinopathy
Diabetic retinopathy is the most common form of diabetic eye disease, in which the light sensitive portion at the back of the eye, called the retina, gets affected.
What is diabetic retinopathy?
The increase in blood glucose levels due to diabetes causes changes in retinal blood vessels. These blood vessels, especially the smaller ones called capillaries, become fragile and can bleed, or leak fluid into the retina. These can cause haemorrhages and swelling in the retina and macula.
In more severe cases, abnormal blood vessels begin to grow on the surface of the retina. These blood vessels and bleed, and also cause traction on the retina, causing serious loss of vision. Unless treated, diabetic retinopathy can gradually become more serious and progress from ‘background retinopathy’ to proliferative retinopathy with new vessels, which can cause decrease of vision and even lead to blindness.
The first type of diabetic retinopathy is called Non Proliferative Diabetic Retinopathy, and the second is called Proliferative Diabetic Retinopathy. Both may or may not be associated with diabetic macular edema or swelling.
How is diabetic retinopathy caused?
Diabetic retinopathy is caused by prolonged exposure of the blood vessels to high blood sugar. This weakens the walls of the blood vessels, making them prone to bleeding and fluid leakage. Over time, too much sugar in the blood can also lead to blockage of the tiny blood vessels that nourish the retina, cutting off its blood supply. This results in inadequate supply of oxygen to the retina, prompting the growth of new abnormal blood vessels.
What are the risk factors for diabetic retinopathy?
Anyone who has diabetes, especially with uncontrolled blood sugars, can develop diabetic retinopathy. The major risk factors for developing the eye disease include
Duration of diabetes: The longer you have diabetes, the greater your risk of developing diabetic retinopathy. If you have had diabetes for longer duration, the risks of disease are higher. This is why an annual dilated examination of the retina is mandatory for diabetics.
Poor blood sugar control: For the same duration of disease, the risk of diabetic retinopathy is less in patients with better blood sugar control. In case you have already been detected with diabetic retinopathy, you can halt or decrease its progression by making sure that your blood glucose levels are well controlled.
High blood pressure: Uncontrolled high blood pressure compounds the deleterious effects of diabetes, increasing the risk of diabetic retinopathy.
High cholesterol: High blood cholesterol also causes an increased risk of diabetic retinopathy and so doctors advise a strict serum cholesterol control for eye health.
Pregnancy: Pregnancy is associated with increased risk of development and progression of diabetic retinopathy .The greatest risk of worsening occurs during the second trimester and persists till almost one year after childbirth.
Smoking: Smoking is a major risk factor for diabetic retinopathy. It results in higher blood pressure and higher serum cholesterol levels, and also impairs insulin activity. In addition, smoking can also increase the incidence of cataract and age related macular degeneration.
Race: Certain populations have a higher predilection for developing diabetic retinopathy. These include people with African, Hispanic or Native American ancestry.