DIABETES MELLITUS & YOUR EYE

Diabetes is basically a disease in which there is an abnormally high glucose level in the blood of the patient. This is due to a deficiency of insulin which affects the metabolism of carbohydrate, protein, fat, water and electrolytes. The longstanding metabolic derangement can result in permanent damage to the blood vessels of different organs of the body.

THE GENERAL COMPLICATION OF DIABETES
The long term complication of diabetes are widespread and can affect multiple organs and parts of the body as follows:

1. The Eye
2. Kidney failure
3. Diabetic neuropathy causing loss of sensation especially of the extremities of the limbs, muscle wasting, impotence etc.
4. The diabetic foot is due to a combination of factors of reduced blood supply, poor sensation and infection leading to death of tissue (necrosis) of the foot.

DIAGNOSIS OF DIABETES
The diagnosis of diabetes is measuring the sugar level of the blood when the patient is fasted. Sometimes, additional tests like oral glucose tolerance test may be necessary.

THE EYE COMPLICATIONS OF DIABETES

1) Diabetes retinopathy - blood vessels of retina damage resulting in bleeding, leaking of protein and lack of blood supply (ischaemia).

2) Cataracts - opacity of lens in the eye.

3) Glaucoma - high pressure in the eye.

4) Loss of sensation of the cornea (surface of the eyeball).

5) Paralysis of nerves controlling eyeball movements (oculomotor nerves).

This article will concentrate on Diabetic Retinopathy which is the most important complication to the eye. Diabetic retinopathy is caused by damage of the blood vessels supplying the retina. The retina is the nerve layer that is at the back of the eyeball. The retina is sensitive to light and enables the eye to see and its function is vital for the vision of the eye. The damaged blood vessels may leak blood or fluid and damage the retina. The diabetic retinopathy is classified into various stages depending on severity and potential to threaten loss of vision.

HOW DO YOU KNOW IF YOU HAVE DIABETIC RETINOPATHY?
Early diabetic retinopathy may not have any symptom but the more advanced stages may be associated with blurring of vision and also seeing floaters (black clouds) due to bleeding.

DETECTION AND DIAGNOSIS
Basically, a detail eye examination with dilated pupils is essential to assess the retina properly for retinopathy.

RISK FACTORS OF DIABETIC RETINOPATHY
These are the factors that will make your diabetic retinopathy worse:

1. Duration of Diabetes
   After 10 years of diabetes, retinopathy is present in 20% of patients and after 20 years, retinopathy is present in 80% of patients.
2. Poor diabetic control
3. Kidney disease
4. High blood pressure
5. Pregnancy
6. High cholesterol
7. Cigarette smoking

TREATMENT OF DIABETIC RETINOPATHY

1. Laser treatment may be necessary to stop progression of retinopathy. The initial damage due to the retinopathy is usually not reversible.
2. Correcting all the risk factors as far as possible.

GOLDEN RULES TO REMEMBER

1. Diabetic Eye Screening, about once a year.
2. Good diabetic control. The corner stone of good control is diet control, regular exercise and anti-diabetic medication when necessary.
3. Correcting all the risk factors of diabetic retinopathy.
4. Laser treatment is mainly to prevent further damage to the retina and usually cannot reverse the existing damage.
5. Diabetes is a life long condition and needs regular monitoring and treatment.

DR DENNIS KONG KET MING
Consultant Ophthalmologist