Diabetic Retinopathy
Diabetic retinopathy is a complication of diabetes, which affects the retina of the eye. The retina is like a photographic film of the camera and is that part of the eye where light filtering through the lens of the eye is focussed. The focussed light images are then carried to the brain by the optic nerve.

The retina contains numerous blood vessels which nourish it. In diabetes, there is weakening of these blood vessels. These weakened blood vessels may leak blood or fluid and hence, may not perform their job of nourishing the retina. When leaking blood or fluid damages the retina, the images sent to the brain become blurred and the person with diabetes complains of inability to see clearly. 

The risk of developing diabetic retinopathy is high when a patient has had diabetes for a long time. About 60% of patients having diabetes for 15 years or more will have some blood vessel damage in their eyes and a certain percentage of these will progress to have serious problems with vision. Because diabetes itself is fairly common, diabetic retinopathy has become one of the leading causes of blindness in the country. It is said that a diabetic person is 25 times more prone to blindness than the non-diabetic. 
Forms of Diabetic Retinopathy
Background Diabetic Retinopathy
This is considered an early stage of diabetic retinopathy. Although the patient feels perfectly normal, the ophthalmologist may see evidence of damaged blood vessels, small haemorrhages and fatty deposits on the retina. Though gradual blurring of vision may occur, eyesight is usually unaffected by background retinopathy. Hence, background diabetic retinopathy can go unnoticed unless detected by an ophthalmologist. Background retinopathy is a warning sign and can progress to a more serious, sight endangering stage of proliferative retinopathy.
Proliferative Retinopathy
This develops from background retinopathy. In an attempt to nourish the under nourished retina because of weakened blood vessels, new blood vessels grow (proliferate) on its surface. These new vessels are fragile and may rupture and bleed into the vitreous cavity producing sudden loss of vision.

When bleeding occurs in proliferative retinopathy, the patient has cloudy vision or complete loss of sight, though there is no pain. The severe form of diabetic retinopathy required immediate medical attention.
Treatment
Probably the most significant treatment is the use of Laser surgery to seal or photo-coagulate the leaking new blood vessels, which are responsible for bleeding inside the eye. The procedure focusses a powerful beam of laser light onto the damaged retina. small bursts of the laser energy seal leaking vessels, reduce new vessel growth and cause existing ones to shrink and close. If diabetic retinopathy is detected early, photo-coagulation by ophthalmic laser surgery may help stop continued damage. Even un advanced stage of the disease, it can reduce the chance of patient having severe visual loss.

However, photocoagulation cannot be used in all patients. If bleeding has occurred inside the eye because of leaking new vessels, surgical treatment must be used. In this surgical procedure called Vitrectomy, the blood-filled vitreous is removed from the eye and replaced with a clear, artificial solution. The ophthalmologist may recommend a Vitrectomy soon after the vitreous becomes clouded by blood, or wait upto 3-6 months to see if the eye clears itself naturally. The timing for each patient depends on the extent of damage to the eye and the condition of the other eye.
Prevention
The key to prevention leis in early detection of diabetic retinopathy. This involves a painless examination of the interior of the eye called INDIRECT OPTHALMOSCOPY. For further information, the ophthalmologist may perform an investigation called Fluorescein Angiography. This involves injection of a dye into the bloodstream through a vein, usually in the arm. Photographs of the inside of the eye are then taken as the dye is carried through the blood vessels of the eye, showing areas of leakage or poor blood flow, if any.

Hence, for successful prevention, diabetics should be aware of the risks for developing Diabetic Retinopathy and should:

1) Have regular eye check ups
2) Take their medications and follow a course of diet as directed by them to control diabetes