Diabetes and the eye: Diabetic retinopathy

By Dr Neeraj Jain – MD, DNB, MNAMS (Consultant Ophthalmologist)

What is diabetic retinopathy?

If you have diabetes, you probably know that your body can’t use or store sugar properly. When your blood sugar is high, it damages the blood vessels throughout the body, particularly vessels in the kidney and the eye. When the blood vessels in the eye are affected, the condition is called as diabetic retinopathy.

What happens in diabetic retinopathy?

The retina is the multilayered innermost lining of the eye, which works as a visual sensor, detecting visual images and transmitting these to the brain. This retina acquires nourishment for its proper functioning, from blood vessels. In diabetes, when these blood vessels are damaged, they leak fluid or blood, form abnormal vessels and scar tissue. This leakage affects the ability of the retina to detect and transmit images.

What are the types of diabetic retinopathy?

There is a complex system for the classification of diabetic retinopathy to give a precise description. But for a lay person, there are two types of diabetic retinopathy.

The first is background retinopathy, which is the early stage. There are very minimal signs and symptoms in the beginning.  A detailed eye examination is the only way to diagnose changes in the vessels/retina of your eyes.

As the disease progresses, blurring of vision for far and near objects, floaters, and progressive loss of vision will be noticed by the patient.   Generally the progression is faster with poor control of diabetes and slow with good control of diabetes.

When retinopathy becomes advanced, there is a growth of abnormal blood vessels in the retina. These new vessels are the body’s attempt to overcome and replace the vessels which have been damaged by diabetes. Unfortunately these new vessels are of poor quality. They bleed and pull the retina, causing a total loss of vision. This stage, called proliferative retinopathy, requires immediate medical attention.

Will I develop diabetic retinopathy?

Everyone who has diabetes is at risk of developing diabetic retinopathy.

It may be absent when you are diagnosed first as a diabetic. As the years pass, the possibility of having diabetic retinopathy will increase.

In its early stages, you may not notice any change in your vision, but it can lead on to serious consequences later in life.

Diabetic retinopathy is one of the leading causes of blindness among adults. If untreated, there is a very high risk of becoming blind. A diabetic is 25 times more likely to go blind than a person in the general population.

The longer one has diabetes, the higher the incidence of developing diabetic retinopathy. After 20 years of diabetes nearly all patients with type 1diabetes and over 60% of patients with type 2 diabetes have diabetic retinopathy.

Is there any treatment available?

Treatment is necessary to prevent/delay severe loss of vision. Regular eye exams are crucial for all persons with diabetes. The progressive damage to the blood vessels in the eye can be slowed with treatment.

Diabetic retinopathy can be treated with laser photocoagulation to seal off leaking blood vessels and destroy new growth.

In some patients, blood leaks into the vitreous humor and clouds vision. A procedure called a ‘vitrectomy’ removes blood that has leaked into the vitreous humor.

There are some new medicines which can be injected in the eye (avastin, tricort, etc) to slow down the damage due to diabetes.

What else can diabetes do to my eyes?

Diabetics are prone to early cataract and glaucoma. Cataract is treated with phacoemulcification. In this method of cataract surgery, the lens is fragmented by ultrasonic vibrations and simultaneously irrigated and aspirated; properly done this surgery can return your vision to what it was prior to the cataract.

Glaucoma too, can be controlled by regular medication or surgical procedures. Diabetics are more likely to have glaucoma than people in the normal population. So a regular screening for glaucoma along with diabetic retinopathy, is a routine protocol in an ophthalmological follow-up.

What should I do?

1.    Tight control of blood glucose: It not only delays onset of retinopathy but also slows the progression of established retinopathy.

2.    Regular 6 monthly/annual detailed eye examinations: Until you develop symptoms it is the only way to find out about the damage in your retina.

3.    Diet modification, exercise and medication: All three are essential to control your diabetes.