An explanation of diabetic retinopathy
Most people with diabetes see well and have no major eye problems. Some people develop 'cataracts'. These cause misty vision, and can be removed with a relatively quick operation.
If your diabetes has been a little more severe, you may develop 'retinopathy ', a disease of the retina of your eye. If your sight has already been damaged, it can be very difficult coping with everyday life. For information that may help a little, see Coping with Poor Vision.
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. and then passes through the eye to reach the retina.
The messages about what you see are then passed on to the brain.See Animation.
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.
There are four 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.
- 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.
- background retinopathy .... early changes.
- maculopathy ....this is more serious. Eventually your sight may become reduced. Laser and blood pressure control help.
- pre-proliferative or non-proliferative stage before the new blood vessels start growing.
- 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.
There are other conditions that may be present:
- retinal scarring ... scars develop on the surface of the retina
- a vitreous haemorrhage .. this occurs when the new vessels bleed
- a retinal detachment ... the retina can peel off the back of the eye
However, 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. Many people with diabetes do go on to develop retinopathy, and this can damage the sight severely. 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. Such matters are discussed briefly below, but in more details in other sites such as the Diabetes UK site.
If you have been diabetic for ten years or more, especially if you have type 2 diabetes (NIDDM: basically non-insulin dependant), you may have a combination of maculopathy and proliferative disease.
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 as far as possible to
- don't smoke
- keep to a healthy diet
- have regular exercise
- have regular checks of your eyes (with dilated pupils)
- have regular checks or your glucose, HbA1C, & blood pressure,
- attend your annual diabetic review where your urine protein, feet, and other checks are carried out
- keep your blood sugar, blood pressure, and fat levels as normal as possible as below
- keep a diary of glucose readings
- record your lipids and blood pressure in the comments section of your glucose diary or in your shared care card.
- remember if you have (but are not yet diabetic) impaired glucose tolerance (pre-diabetes in the US) you may progress to diabetes. A healthy diet, not being overweight, having lots of exercise, can delay or prevent this progression.
- we need to pay attention ot improving control
- See the Prevention Movie, and Prevention Pages
- see epidemiology
- If your parents had heart or another type of vascular disease you may be more prone to complications also.
Is your diabetes controlled?
are you on the graphs below?
Is your HbA1c below 7%? enlarge....HbA1c
Is your blood pressure below 130/80? enlarge
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.
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.
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.
As a community exercise and lifestyle measures are needed to prevent more people developing the condition, starting as children. Remember, if you have diabetes, there is a direct relationship between diabetic control (sugar and blood pressure and smoking) and likely damage. Also, there is a direct relationship between alcohol and blood pressure.
The World Health Organisation recommend the relations of people with diabetes should take lifestyle precautions, as doing so will prevent or delay diabetes:
- not smoke
- have a healthy diet
- lose weight if overweight if they want to avoid 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.
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 foundation 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) that make fresh new blood vessels grow, and 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.
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.
For the examination, you should bring
- a list of tablets/medication you use
- your diabetic diary with a recent blood pressure, HbA1c result, blood sugars, and any problems you are having
- you should never drive home from the eye clinic, so never drive
The examination will include
- blood pressure (not all visits)
- retinal photographs (not all visits)
- dilating your pupils
- a retinal examination
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.
Some visits extra tests/procedures may be needed
- Your pupils need to be dilated. Standard drops are tropicamide 1% and phenylephrine 2.5%.
- generally these work for 1-2 hours, with some residual effect for the rest of the day.
- Rarely the phenylephrine component may cause the pupils tostay dilated for 3 days (mention this to your doctor if it happens to you).
- You can be allergic to either of the drops, usually the phenylephrine. If this happens your eyes will be red and itchy for a week after the drops. Again, mention this to your doctor if it happens to you.
- It is dangerous and illegal to drive after the drops. Some people find they can drive, but you are strongly advised not to. You must wait until they wear off. Drops are used for every retinopathy examination. See
In Europe retinopathy is reducing in all areas, especially those without much poverty. It is increasing in developing countries as diabetes and obesity increase.