Diabetic Retinopathy
Diabetic retinopathy is the term used to cover various changes in the retina( the thin layer of light-sensitive tissue at the back of your eye) - brought on by long-term diabetes. Diabetic retinopathy is caused by prolonged high blood glucose levels. Over time, high sugar glucose levels can weaken and damage the small blood vessels within the retina.
This can lead to a number of different problems, including:
- Microaneurysms - Swelling of blood vessels
- Exudates - Small leaks of fluid from damaged blood vessels
- Haemorrhages - small bleeds from damaged blood vessels
- Blockages - Blocked vessels can starve the retina of blood and oxygen, causing weak new blood vessels to grow on the surface of the retina
Not all diabetic retinopathy affects your vision. Milder diabetic retinopathy is called background diabetic retinopathy and consists of microaneurysms, tiny (dot) haemorrhages and exudates (fatty deposits leaking from retinal blood vessels). More severe diabetic retinopathy is called proliferative diabetic retinopathy and is caused by blockages in the retinal blood vessels which starves the retina of its blood supply. The retina then tries to make new blood vessels which are fragile and can bleed causing a vitreous haemorrhage or can cause scar tissue which can detach the retina (tractional retinal detachment). In addition to background and proliferative retinopathy, some patients can develop diabetic maculopathy. This is caused by leakage of fluid from blood vessels in the centre of the retina (the macula)
Background diabetic retinopathy does not tend to affect vision but both diabetic maculopathy and proliferative diabetic retinopathy can cause severe visual loss if left untreated.
Treatment
Prevention is better than cure. The risk of developing diabetic retinopathy can be reduced with good diabetic control, control of blood of blood pressure, stopping smoking and control of cholesterol level. Diabetic patients should have annual screening photographs of the back of their eyes. This is to detect early changes that can be treated before they affect vision.
Background diabetic retinopathy does not require treatment but will require monitoring with photographs. Diabetic maculopathy can be treated with laser treatment to reduce leakage from retinal blood vessels. Severe diabetic maculopathy is managed using anti-growth factor (anti-VEGF) injections into the eye itself. Large studies have shown superior results for this type of treatment when compared to laser. 3 times more patients achieved better vision with anti-growth factor injections compared to laser. The injections are largely painless and given as an initial course of 3 injections followed by further injections if required. The anti-growth factor injection currently used is Ranibizumab (Lucentis). If the maculopathy does not respond to Ranibizumab, then a steroid implant can be used in the eye in selected patients. This is called Iluvien and it’s beneficial effect can last up to three years.
Proliferative diabetic retinopathy is treated with laser in the first instance to shrink any abnormal blood vessels to reduce the risk of haemorrhage. If vitreous haemorrhage or tractional retinal detachment are present then vitrectomy surgery can be used to clear the blood and scar tissue and improve vision.
