Diabetes Mellitus


Diabetes Mellitus is a disease that occurs when the pancreas does not secrete enough insulin or the body is unable to process it properly.  Insulin is the hormone that regulates the level of sugar (glucose) in the blood.  Diabetes can affect children and adults.

How does diabetes affect the retina?

Patients with diabetes are more likely to develop eye problems such as cataracts and glaucoma, but the disease’s effect on the retina is the main threat to vision. Most patients develop diabetic changes in the retina after approximately 10 years. The effect of diabetes on the eye is called diabetic retinopathy.

Over time, diabetes affects the circulatory system of the retina. First, the arteries in the retina become weakened and leak, forming small, dot-like haemorrhages.  These leaking vessels often lead to swelling or oedema in the retina and decreased vision.

In the next stage circulation problems cause areas of the retina to become oxygen-deprived or ischaemic.   New, fragile, vessels develop as the circulatory system attempts to maintain adequate oxygen levels within the retina.  This is called neovascularisation. Unfortunately, these delicate vessels haemorrhage easily.  Blood may leak into the retina and vitreous, causing spots or floaters, along with decreased vision.

In the later phases of the disease, continued abnormal vessel growth and scar tissue may cause serious problems such as retinal detachment.

Signs and Symptoms

The effect of diabetic retinopathy on vision varies, depending on the stage of the disease.  Some common symptoms of diabeticretinopathy are listed below, however, diabetes may cause other eye symptoms.

  • Variable blurred vision (this is often linked to blood sugar level changes)
  • Floaters and flashes
  • Sudden loss of vision
  • Detection and Diagnosis

Diabetic patients require routine eye examinations so related eye problems can be detected and treated as early as possible. Most patients with diabetic retinopathy are referred to vitreo-retinal surgeons who specialise in treating this disease.


Diabetic retinopathy is treated in many ways depending on the stage of the disease and the specific problem that requires attention.

The abnormal growth of tiny blood vessels and the associated complication of bleeding is one of the most common problems treated by vitreo-retinal surgeons.  Laser surgery called pan-retinal photocoagulation (PRP) is often the treatment of choice. PRP destroys oxygen-deprived retinal tissue outside of the patient’s central vision. While this creates blind spots in the peripheral vision, PRP prevents further growth of the fragile vessels and seals the leaking ones. The goal of the treatment is to stop the progression of the disease.

Vitrectomy is another surgery for diabetic patients who suffer a vitreous haemorrhage (bleeding in the gel-like substance that fills the centre of the eye). The surgeon may also gently cut strands of vitreous attached to the retina that create traction and could lead to retinal detachment or tears. Retinal tears are often sealed with laser surgery.  Retinal detachment requires surgical treatment to reattach the retina to the back of the eye. The prognosis for visual recovery is dependent on the severity of the detachment.


Researchers have found that diabetic patients who are able to maintain appropriate blood sugar levels have fewer eye problems than those with poor control.  Diet and exercise are important in the overall health of those with diabetes.

Diabetics can also greatly reduce the possibilities of eye complications by scheduling routine examinations with an eye care practitioner.  Many problems can be treated with much greater success when caught early!