Diabetes and the Eyes

Diabetes is a complex, serious, chronic (long-lasting) condition. It can have substantial effects on many parts of the body including the eyes, nerves, brain, kidneys, heart and limbs. These effects are largely the result of damage to blood vessels.

A critical aspect of diabetes is that, although it cannot be cured, the complications and related health problems can be significantly reduced or prevented in the vast majority of people with optimal management of blood glucose levels, careful attention to diet, weight management, and regular physical activity.

Diabetes is a very serious condition. It requires daily self-management and personal responsibility including the management of blood glucose levels, blood pressure and blood lipids through the maintenance of a healthy weight, healthy diet and healthy activity. Access to a multidisciplinary health professional team will support diabetes care in an individualised manner.

Three main types of diabetes:

• Type 1 diabetes is an autoimmune condition in which the immune system is activated to destroy the cells in the pancreas, which produce insulin. It is not known what causes this autoimmune reaction.

  Type 1 diabetes is not linked to modifiable lifestyle factors and cannot be prevented. Type 1 diabetes can occur at any age though onset is commonly in children, adolescents and young adults. All people with type 1 diabetes need insulin therapy to survive.

• Type 2 diabetes is a chronic condition in which the body becomes resistant to the normal effects of insulin and/or gradually loses the capacity to produce enough insulin in the pancreas.

  It is not known what causes type 2 diabetes. Type 2 diabetes is associated with modifiable lifestyle risk factors (overweight/obesity, unhealthy diet, physical inactivity, stress). Type 2 diabetes also runs in families. Type 2 diabetes commonly develops in adults, although it is becoming more common among children and young adults.

• Gestational diabetes is a type of diabetes that occurs during pregnancy and affects 5-10% of pregnancies in Australia. This condition normally disappears after the baby is born, however both the mother and the baby have a higher chance of developing type 2 diabetes later in life.

How the eye works

The eye is very much like an old-style film camera. The front of the eye, comprising the cornea, iris, pupil and lens, focuses the image onto the thin retina, which lines the back of the eye. The retina is sensitive to light and acts like the film in the camera, capturing images and then sending them via the optic nerve to the brain, where the images are interpreted. The retina is a veryactive, complex nerve tissue and is supplied with blood by a delicate networkof specialised blood vessels.

Light entering the eye is focused onto an area of the retina called the macula, which is about the size of a pinhead. The macula is a highly specialised part of the retina and is responsible for seeing fine detail for activities such as reading and writing, and to recognise colours. The rest of the retina gives side (peripheral) vision.

How does diabetes affect the eye?

Diabetes can affect the eye in a number of ways:

• Transient blurring of vision: The unusual changes in blood glucose levels resulting from diabetes can affect the shape of the lens inside the eye, hence changing the focus, especially when blood glucose levels are high. This can result in blurring of vision, which comes and goes over the day, depending on blood glucose levels. This is generally a short term effect, but may impact some people for several months.

• Diabetic retinopathy: This is the most common and most serious diabetic eye disease. It is the leading cause of blindness in working-age Australians.

• Cataract: A longer-term effect of diabetes is that the lens of the eye can become cloudy. This is called cataract. Cataracts can form in anyone, but they are more frequent and occur earlier in life in people with diabetes.

• Glaucoma: Diabetes increases the risk of glaucoma, which results in progressive damage to the optic nerve at the back of the eye. While this normally develops slowly, without symptoms in the early stages, it can lead to blindness if not detected early and treated effectively.

Prevalence

Diabetic retinopathy is the leading cause of preventable blindness in working age people in Australia and is considered to be a significant health threat worldwide¹. Almost 1.1 million Australians have diagnosed (known) diabetes².

Of these, over 300,000 have some degree of diabetic retinopathy, and about 65,000 have progressed to sight-threatening eye disease¹.