An explanation of diabetic retinopathy

David Kinshuck

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Most people with diabetes see well and have no major eye problems. But if your diabetes has been a little more severe, or if you have had it for a long time. you may develop 'retinopathy '. Retinopathy is damage to the retina.

Patients with retinopathy can lose eyesight, making it be very difficult coping with everyday life.


What is the retina?

The 'retina' is the film at the back of your eye, like the film in a camera. This is shown in the picture. Light enters your the eye ... from the left in this picture. The light then passes through the eye to reach the retina.
The messages about what you see are then passed on to the brain. Animation.


What is diabetic retinopathy?

Diabetic retinopathy is the name given to 'disease of the retina' due to diabetes, and is described below. Blindness from retinopathy can in theory be prevented, and has in Iceland. See. This has been done by regular eye checks and people controlling their diabetes.


Types of retinopathy

There are five main types of retinal damage that can occur if you are diabetic. Unfortunately the condition may progress from no or mild retinopathy to a much more severe type.

  1. No retinopathy.... many people have a basically healthy retina. If you can control your diabetes and blood pressure at this stage it will help prevent or slow down any harmful changes.
  2. Background retinopathy .... early changes.
  3. Maculopathy ....this is more serious. Eventually your sight may become reduced. Laser and blood pressure control help.
  4. Pre-proliferative  or none-proliferative stage before the new blood vessels start growing.
  5. Proliferative retinopathy ... when the new vessels grow. These blood vessels are very delicate and can bleed easily. Laser is very effective in stopping the new vessels grow.
  6. retinal scarring and thinning from the condition.

There are other conditions that may be present:

So if you have 'no' retinopathy you should still look after your diabetes, because this reduces your chance of getting it, and you may even feel better for it. Nearly everyone whose diabetes is uncontrolled  will develop severe retinopathy, and this can damage the sight severely. Few people with good control develop reinopathy, and thos that do develop it will have milder form that can be treated. The different types of retinopathy are described in adjacent pages.

Controlling your diabetes and blood pressure also helps to prevent other problems such as neuropathy and kidney damage. This is discussed in more detail in other sites such as the Diabetes UK site.

Younger patients tend to develop proliferative retinopathy.  Older patients who have type 2 diabetes (NIDDM: which starts as non-insulin dependant), may have a combination of maculopathy and later proliferative retinopathy


Preventing Eye disease

retinopathy progression ate 4x higher in smokers


You cannot tell if your eyes have been damaged by diabetes; your eyes have to be checked by a doctor or optometrist who is expert at finding the condition.

This check needs to be carried out every year. What can you do to stop retinopathy developing?

More details are discussed in Preventing problems, but basically you need

Is your diabetes controlled?
Where are you on the graphs below?


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Is your HbA1c below 7%?   

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Is your blood pressure below130/80? 


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The rise in blood pressure after 8 units of alcohol how much  do you drink?
(4 pints of beer)


Blood pressure control is discussed in more detail. Exercise, a healthy diet, avoiding obesity, low salt, and less than one drink of alcohol a day help. This graph shows the effects of 8 units of beer in one evening.

Your weight is very important: the lighter you are, the less insulin you need. Sometimes losing weight can therefore make the diabetes disappear; losing weight (if you are overweight) certainly makes your diabetes easier to control.


Causes of type 1 diabetes

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Type one diabetes usually begins in young people. The body's immune system attacks the islet cells in the pancreas where insulin is made.

As the damage increases, less less insulin is made, and diabetes develops.

This inflammation may be started off by an infection; your immune system reacts against a virus (the virus acts as a 'trigger'), but becomes 'misdirected', and attacks the islet sells instead.

Thus type 1 diabetes is caused by a 'faulty' immune system. Why do some people get diabetes and others do not? ......because we all have inherited different immune systems and slightly different coatings on the different cells of our body. It is a certain combination of virus/immune system/coating on cells that makes diabetes develop.
Type 1 diabetes is much commoner in Western Countries such as parts of Scandinavia than other countries. Why this is remains a mystery, but breast feeding up to six months of age is said to reduce the incidence.
This type of diabetes is also increasing in the UK.
It occasionally occurs in relations: occasionally the twin of a young person with diabetes has had tests that detect the inflammation before there is too much islet cell damage, and drugs have been given to stop the inflammation. A lot of research is taking place in this area.


Causes of type 2 diabetes

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This type of diabetes is also called late-onset on non-insulin dependent (although eventually people often do need insulin). Type 2 diabetes runs in families.

It occurs at a younger age if people have little exercise, smoke, have an unhealthy diet, or get overweight.

Conversely, even if you have the genes likely to make you diabetic, it will be delayed many years or indefinitely with a healthy lifestyle.

Some people's genes program them to develop diabetes at a young age, others at a very old age, but it is much more common in the elderly.

This is because the islet cells shrink and make less insulin as you get older. Worryingly, it is increasing at a rate of 10% a year, and is occurring at an ever younger age.


Relations of people with type 2 diabetes's

The World Health Organisation recommend the relations of people with diabetes should take lifestyle precautions, as doing so will prevent or delay diabetes:

The World Health Organisation recommends If you have type 2 diabetes your relations should be tested every 3 years with a fasting blood sugar. In a few years blood tests (testing insulin resistance) may be recommended.


Mechanisms of Retinopathy

How does retinopathy develop? This is explained in more detail (mechanisms). Each retinal vessel is lined by endothelial cells, which form the wall of the cell. The endothelial cell rests on a layer of basement membrane.

In diabetic retinopathy, high sugar and blood pressure levels cause blood flow to increase. The basement membrane layer then becomes thick. The thickened basement membrane then stops the flow of essential chemicals into and out of the retina.

Next, the damaged cell releases special chemicals (growth factors such as VEGF and FGFb). These encourge fresh new blood vessels to grow,

The same chemicals also make the blood vessel leak even more fluid.

It is these new blood vessels and leaky areas that a doctor can see looking into your eye.
Eventually there may be so much damage that the vessel closes up and the retina stops working.

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In several years it may be possible to take a tablet that stops the growth chemicals working, and much research is taking place around the world. No drug is currently in regular use.


Your eye examination

For the examination, you should bring

The examination will include

Once the doctor has examined your eyes, he will decide with you whether or not laser treatment is need. This will be based on the type of retinopathy   you have.


Dilating you pupils

Good news in Birmingham and many other places

In Europe retinopathy is reducing in all areas, especially those without much poverty. It is increasing in developing countries as diabetes and obesity increase.