What Is Diabetic Retinopathy?

Diabetic retinopathy is a complication of diabetes that affects the eyes and the ability to see. In the early stages of diabetic retinopathy there are no symptoms and vision may not change until the disease is advanced.

There are two types of diabetic retinopathy. The first, maculopathy, develops when some of the small blood vessels around the macula (the centre of the retina that provides sharp focus) become blocked. This causes other blood vessels to leak, so that fluid builds up behind the retina causing swelling and loss of sight.

The second, 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. A detached retina always means loss of vision.

Diabetic Retinopathy is a complication of diabetes mellitus which is caused by changes in the blood vessels of the eyes.  The longer one has diabetes the greater the chance of developing diabetic retinopathy.  According to a study, more than one – third of those diagnosed diabetes do not get recommended vision care.  The situation in Pakistan is even worse where awareness programmes are basically aimed at the urban and educated population while the majority of our population is rural based and illiterate.

The cornea and lens focus light onto the retina.  The light rays pass through the vitreous, a clear gel like substance filling the middle of the eye, before reaching the retina, the sensitive layer at the back of the eye.  The retina converts the light signals and sends them through the optic nerves to the brain where they are recognized as images.  The macula is a small area in the centre of the retina that allows us to see fine details clearly.  Any damage to the macula results in blurred vision.  The remaining retina is used for navigational or side vision.

There are two types of diabetic retinopathy:

1. Background diabetic retinopathy.
2. Proliferative diabetic retinopathy.

Background diabetic retinopathy is the earliest form of diabetic retinopathy.  Here the blood vessels which have become fragile because of high blood sugar levels over the years begin to leak fluid and small amounts of blood into the eye.  Sometimes deposits of cholesterol or other fats are also leaked into the retina.  These leaked components are called hard exudates.  This leaked material does not affect vision but the eye is going to go blind unless taken care of.  If the leakage happens to occur on the macula (a small area on the retina that allows seeing things clearly) the vision becomes blurred.  The condition is called macula edema or swelling of the macula.  This is the most common cause of vision loss in diabetes.

The non – proliferative diabetic retinopathy is called 'Proliferative diabetic retinopathy when abnormal blood vessels begin to grow on the surface of the retina or optic nerve head.  This growth of new blood vessels is called neovascularisation.