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What you should know about diabetes and eye health

As world diabetes day approaches here are some facts we think you should know about diabetes and eye health.

What is diabetes?

Diabetes is a disease that is caused by abnormally high levels of sugar in the blood. It develops when the body is unable to produce or use the hormone (insulin) that helps it process and use sugar from food. The disease can cause a lot of complications and can be life-threatening if not detected early and managed properly.

How does diabetes affect the eyes?

Diabetes can cause eye symptoms and vision-threatening eye complications. These include:

  • Vision changes
  • Cataract
  • Retinopathy
  • Glaucoma

Vision changes due to diabetes

People who experience rapid shifts in blood sugar levels or those who maintain high blood sugar levels for prolonged periods tend to experience temporary changes in vision. The vision changes occur because the focusing power of the lens is affected as it swells or shrinks in response to the increase and decrease in blood sugar levels respectively.

Generally, vision gets blurry when blood sugar is high and the lens is swollen. It reverses back to normal when blood sugar gets controlled. However, some hyperopes (those who are longsighted) may experience an improvement in vision with high blood sugar. They may even be able to do without their glasses during that period. This false improvement in vision may be misinterpreted if such people aren’t aware that they have diabetes.


This is the clouding or whitening of the natural lens in the eye. People who have diabetes are much more likely to develop it compared to those who are do not have the disease. They are also more likely to develop it a younger age and have it progress faster to mature cataract compared to those who are do not have the disease.

Cataract in diabetes has been attributed to the damage done to the lens fibres by the frequent swelling and shrinking of the lens as well as other changes that occur in response to fluctuating blood sugar .  

Diabetic Retinopathy

This is the damage done to the retina and its blood vessel as a result of diabetes. It usually does not show any symptoms in the early stage.

In the later stage the following symptoms may be observed:

  • Fluctuating vision
  • Blurry vision that does not improve with glasses
  • Seeing spots or strings (floaters) in your visual field
  • Dark patches in the visual field
  • Gradual or sudden loss of vision

The risk of developing diabetic retinopathy increases as the length of time one has had diabetes increases. It is a progressive condition. The ability to prevent it from progressing from the mild to advanced stage depends on how well blood sugar level, cholesterol and blood pressure are controlled.


Glaucoma is a group of eye diseases that progressively damage the optic nerve leading to vision loss. It often occurs in diabetes as a consequence of advanced retinopathy and is known as neovascular glaucoma.

The abnormal blood vessels that develop due to diabetic retinopathy can grow over the area through which the fluid in the eye (aqueous humour) flows out. This causes the fluid to build up and increase eye pressure. If the high eye pressure is sustained it damages the optic nerve, leading to glaucoma. Click here to learn more about glaucoma.

General tips for the prevention and control of diabetic eye complications

  • Check your blood sugar levels regularly and as much as possible keep it controlled and stable
  • Take your medications as recommended (if your physician prescribes one)
  • Eat healthy food in the proportions recommended for diabetics
  • Exercise daily
  • Keep your weight under control
  • Keep blood pressure and cholesterol levels within normal range
  • Avoid smoking
  • Get your eyes checked regularly
  • Get eye complications treated directly

Direct treatment of diabetic eye complications

In addition to the treatment prescribed by the physician, the following eye complications would require direct eye treatment to prevent or minimize vision loss.   

  • Cataract: Treatment involves surgery that is done to remove the clouded lens and replace it with an intraocular lens.
  • Diabetic retinopathy: Treatment may include the use eye injections to slow or stop the growth of abnormal blood vessels as well as surgery
  • Neovascular glaucoma: Treatment may include the use of eye drops, surgery and treatment of the underlying retinopathy.

Final notes

  • Eye complications of diabetes can cause vision loss and blindness.
  • Early detection and treatment of these complications can reduce your risk of blindness.
  • Since the eye complications of diabetes generally do not show symptoms early, if you have diabetes or are at risk of developing it, it is important that go for comprehensive eye exam annually or as recommended by your eye doctor.