Diabetic Retinopathy

The retina is a very delicate membrane that lines the back wall of the eye. Within it are sensitive photoreceptors which capture the light images that enter the eye. These images are sent through the optic nerve to the brain where they are interpreted into sight.

When diabetic retinopathy develops, the blood vessels which nourish the retina deteriorate as a result of the high levels of blood sugar which are common in diabetics. The deterioration of these blood vessels can be a threat to vision. Background diabetic retinopathy occurs when changes begin to occur in the eye as a result of diabetes.

Background diabetic retinopathy is the most common form of the disease, accounting for about 80% of all cases. It is considered to be the first stage of blood vessel deterioration. Approximately one-fifth of these cases progress to the point where vision is seriously affected.

Proliferative Diabetic Retinopathy

Some cases of background diabetic retinopathy progress to a more advanced stage of deterioration known as proliferative diabetic retinopathy. This form of the condition is very serious and can definitely result in blindness if it is not discovered and treated early.

Diabetics should realize that much of the damage of proliferative diabetic retinopathy can happen without any pain or noticeable symptoms. It is therefore essential that they have frequent eye examinations by a specialist.

In cases of proliferative diabetic retinopathy, some of the deteriorating retinal blood vessels close off, leaving large areas of the retina without the nourishment usually supplied by healthy blood vessels. The closing off of blood vessels is serious, but the problem is intensified when the retina begins to develop new blood vessels to compensate for the loss of the closed off vessels. Unfortunately, these blood vessels are very dangerous to the health of the eye. They can grow out into the vitreous cavity in the centre of the eye. Besides not nourishing the retina properly, these abnormal vessels may cause several other problems including the following:

• Bleeding into the vitreous cavity and blocking the passage of light
• Forming scar tissue that can pull the retina off the back of the eye with its traction
• Distorting the iris, thereby blocking the passage of fluid through the front part of the eye, causing glaucoma.

All of these problems can lead to a serious loss of vision and even blindness, if they are not controlled.

Diabetic Macular Edema

In diabetic macular edema, the blood vessels in the retina weaken and change. Some vessels decrease in size, while others enlarge into balloon like sacs which interfere with the flow of blood. These weakened vessels tend to hemorrhage and leak blood and a fluid called serum. This leakage into the retina causes it to get wet and swollen, resulting in blurred vision.

Treatment for macular edema or proliferative diabetic retinopathy usually involves the use of lasers. This treatment may not improve vision, but it can often prevent vision from deteriorating further. Laser treatment is not always effective so subsequent treatments may be necessary and helpful.

In some cases, a vitrectomy may be performed. During this surgery, the vitreous is removed from the centre of the eye. Air or other gases may be used to replace the vitreous gel until the eye's natural fluids gradually occupy the cavity.