Diabetes can affect your eyes

More than 1.5 million Australians have diabetes, and unfortunately, this number is increasing by about 275 people per day. Many people with diabetes are at risk of eye problems, including diabetic retinopathy, cataracts and glaucoma.

Diabetic retinopathy

Diabetic retinopathy is a disease of the blood vessels of the retina - the light-sensitive layers at the back of the eye which enable us to see. Diabetic retinopathy can develop in anyone who has type 1 diabetes or type 2 diabetes. It occurs more often in people who have had diabetes for a long time, or those whose diabetes is not well controlled. The risk of developing diabetic retinopathy is higher still if you smoke or have high blood pressure, high blood cholesterol levels or kidney disease - these risks all add together. The risk is also higher if you are pregnant.

When a person is diagnosed with diabetes, it isn’t possible to predict at the time whether or not they will get retinal disease. However, around a quarter of people with diabetes have some degree of diabetic retinopathy.

In diabetic retinopathy, the walls of the small blood vessels in the retina are weakened and the vessels may swell, leak, bleed or become blocked. New abnormal blood vessels may grow as the body attempts to repair the damage. However, this may create scar tissue that can pull the retina away from the back of the eye (retinal detachment). There may also be swelling in the central area of vision, known as macular oedema, which can severely impair vision.

eye anatomy

Cataracts

A cataract is cloudiness in the lens of the eye and it leads to vision loss. The main risk factor is getting older but cataracts may develop faster and at a younger age in people with diabetes.

Glaucoma

Doctors estimate that having diabetes doubles the risk of open-angle glaucoma, which is a condition where increased pressure within the eye causes damage to the optic nerve and so impairs vision or causes blindness.

Diagnosis and treatment

Good control of diabetes is the best way of preventing complications.

Having your eyes checked regularly by a doctor is the most effective way of detecting any damage to your eyes at an early stage, when treatment may be most successful. Eye checks should be at least every 2 years, or more often if you are at higher risk of diabetic eye disease (e.g. you have had diabetes for a long time or your sugar levels are not well controlled).

If you are getting symptoms like blurred vision, especially if this comes on suddenly, then see a doctor without delay.

Retinopathy treatment

Laser treatment

If damage to the retina has already occurred, laser treatment (in which a laser beam is directed at the retina to repair damaged blood vessels) is very effective in preventing vision loss. Laser surgery works best if it isn’t done too early or too late - this is another reason why it is vital to detect eye damage promptly.

Ranibizumab

From October 2011, the medicine ranibizumab (Lucentis) is approved in Australia for treating vision loss caused by diabetic macular oedema. It is also used to treat macular degeneration. Ranibizumab is an antibody against a substance, vascular endothelial growth factor (VEGF), that stimulates blood vessels to grow and leak. It must be injected into the middle of the eye, which is usually done in your doctor's office with local anaesthetic. The treatment needs to be repeated monthly while your vision improves and may be combined with laser treatment.

Vitrectomy

Surgery called vitrectomy can be used in more advanced cases to remove blood and scar tissue tugging on the retina from the middle of the eye (vitreous). This clears the view of the retina and allows laser treatment if required.

Cataract surgery

Cataract surgery is usually very successful in improving vision when there is no retinal disease. It often involves removal of the lens of your eye which is replaced with a synthetic (plastic) lens implant.

If you need cataract surgery as well as laser treatment, your doctor will probably suggest you have the laser treatment first if possible. This lowers the risk of visual problems after the cataract surgery.

Additional risk factors

If you have other vascular (blood vessel) diseases such as high blood pressure (hypertension), these should be treated as they can increase the damage to the eye in people with diabetes. Kidney disease also makes eye damage worse, particularly if you have high blood pressure as well. If you are pregnant, good control of diabetes is vital for both you and your baby.

Smoking

If you smoke, you should definitely stop. Nicotine constricts all blood vessels, which can be even more harmful to a person with diabetes. In addition, doctors believe smoking undoes the good work that good blood sugar control has on the blood vessels. Talk to your doctor about giving up now. There are many methods available to help you.

The good news is that with regular eye checks and following your doctor’s recommendations, blindness from diabetes can be reduced just as effectively as it has been from other diseases such as trachoma, river blindness and vitamin A deficiency.

Last Reviewed: 20 October 2011
Reproduced with kind permission from Dr Thomas D. Walker, Ophthalmologist, ACT.

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References

1. Diabetes Australia. Diabetes in Australia (last updated 15 Sep 2010). http://www.diabetesaustralia.com.au/en/Understanding-Diabetes/Diabetes-in-Australia/# (accessed Oct 2011).
2. Australian Diabetes Council. Diabetes and your eyes (revised Aug 2010). Talking diabetes No.43. http://www.australiandiabetescouncil.com/Resources/PDFs/NDSS-Information-Sheets/DIABETES---YOUR-EYES-2010.aspx (accessed Oct 2011).
3. MayoClinic.com. Diabetic retinopathy (11 Feb 2011). http://www.mayoclinic.com/health/diabetic-retinopathy/DS00447 (accessed Oct 2011).
4. Centre for Vision Research, Westmead Millennium Institute. Blue Mountains Eye Study [website]. http://www.cvr.org.au/bmes.htm (accessed Oct 2011).
5. Diabetes Australia. Diabetes management in general practice. Guidelines for type 2 diabetes (17th ed.) Canberra: Diabetes Australia; Jul 2011. http://www.diabetesaustralia.com.au/en/For-Health-Professionals/Diabetes-National-Guidelines/#Diabetes-Management-in-General-Practice (accessed Oct 2011).
6. Australian Diabetes Society. Guidelines for the management of diabetic retinopathy. Canberra: Commonwealth of Australia; 2008. http://www.nhmrc.gov.au/guidelines/publications/di15 (accessed Oct 2011).
7. Novartis. Lucentis (ranibizumab) product information. Sydney: Novartis, 2011. Date of TGA approved information: 11/10/2011.
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