Monday, 26 July 2010

Diabetic Retinopathy - The Facts


















Apologies in advance for the length of this post!!!!  Today's post is going to be totally factual rather than me just rambling on about what I've been up to and it will hopefully explain everything you need to know about Diabetic Retinopathy, including how it occurs, symptoms, the NHS National Screening Programme, how it affects the eye(s), the different stages of the disease, the treatment involved, how to help to prevent the disease and the outlook for people who have Retinopathy. 


I realise I have done part of a blog about this before but I really want to try and raise awareness of this particular complication of Diabetes as it's very close to my heart, so I'm sure you won't mind me repeating myself a bit!!! Oh, and by the way, I have to admit that a lot of the factual information is taken from various websites and not actually written 100% by me, as you will probably be able to tell.


WHAT IS DIABETIC RETINOPATHY???
Retinopathy is a general term used to describe various disorders of the retina. Retinopathy is caused by the tiny blood vessels next to the retina and is often a result of diabetes, hence the term 'diabetic retinopathy.'  

WHAT IS THE OUTLOOK FOR PEOPLE WITH DIABETIC RETINOPATHY???
Diabetes can have a number of effects on our vision. The most common is on the retina. The walls of the blood vessels in our eyes can become weak and over time, the walls begin to bulge. This creates an 'eddy' in the blood flow which can eventually block. Blood and other fluids start to leak into the retina and hard deposits are left there. Because of the reduction in blood flow the body grows new blood vessels. However, these veins are fragile and tend to rupture suddenly leaking blood into the vitreous. This will lead to a sudden and dramatic loss of vision, however, this may clear over time.


HOW THE EYE WORKS
Your eye has a lens and an aperture (opening) at the front known as the pupil, which adjust to bring objects into focus on the retina at the back of the eye. The retina is made up of a delicate tissue that is sensitive to light, rather like the film in a camera. It also contains a fine network of small blood vessels.


At the centre of the retina is the macula, which is a small area about the size of a pinhead. This is the most highly specialised part of the retina and is vital because it allows you to see fine detail for activities such as reading and writing and also to recognise colours. The other parts of the retina give you side vision (peripheral vision). Filling the space in front of the retina is a clear jelly-like substance called the vitreous gel.


THE NHS NATIONAL SCREENING PROGRAMME
In 2005 The Department of Health set up a national screening programme for diabetic retinopathy. If you are 11 years of age or over and you have diabetes, you should be offered annual screening.  The screening programme was introduced because, if diabetic retinopathy is detected early enough, it can be treated effectively using laser treatment.


During screening, eye drops are used to make your pupils large and photographs of your retina are taken. As the photographs are being taken, you will see flashes of bright light, but usually it is not uncomfortable.  The eye drops may cause your eyes to sting slightly and your vision may become blurred about 15 minutes after the procedure ends. The blurring can last between two and six hours, depending on what sort of eye drops were used.


SYMPTOMS OF DIABETIC RETINOPATHY

Diabetic retinopathy does not usually cause any symptoms until it has reached an advanced stage. In some cases, the only noticeable symptom is a sudden and complete loss of vision. This is why regular screening is so important.
Symptoms of diabetic retinopathy include:
•discoloured spots (known as floaters that ‘float’ in your field of vision
•blurred vision
•your vision becomes blocked by patches or streaks
•reduced night vision, and, most serious
•sudden vision loss


RISK FACTORS FOR DIABETIC RETINOPATHY
Duration of Diabetes

The biggest risk factor for diabetic retinopathy is the length of time that you have lived with diabetes.  For people with type 1 diabetes, 90% will have some degree of diabetic retinopathy after 10 years of having symptoms.  For people with type 2 diabetes who do not need to take insulin, 67% will have some degree of diabetic retinopathy after 10 years of symptoms.  For people with type 2 diabetes who need to take insulin, 79% will have some degree of diabetic retinopathy after 10 years of symptoms.

Blood Glucose Level
The higher the levels of glucose in your blood, the greater your risk of developing diabetic retinopathy. People with high blood glucose levels are more likely to progress to advanced diabetic retinopathy.  Blood glucose levels are measured using a test known as the HbA1c test. HbA1c is a form of haemoglobin, the oxygen-carrying chemical in red blood cells that has glucose attached to it.  Small changes in the levels of HbA1c can greatly affect the risk of developing diabetic retinopathy. For example, people with an HbA1c level of 8% are 40% more likely to develop diabetic retinopathy than people with an HbA1c level of 7%.


High Blood Pressure
People with high blood pressure (hypertension) are likely to progress to advanced diabetic retinopathy.


THE DIFFERENT STAGES OF DIABETIC RETINOPATHY
If diabetic retinopathy is detected during screening, you will be given information about how far the condition has progressed. This will determine the type of treatment you will receive.


Background Retinopathy
This is the first stage of diabetic retinopathy, it begins initially by acute swelling in the walls of the blood vessels. Spots known as micro aneurysms form on the retina and appear on the wall as small red coloured dots. There are also small yellow patches, which may form. This is a result of exuding protein from the blood stream onto the retina. Other marks on the retina at this stage could potentially be a haemorrhage, which appears in a similar form. At this stage of retinopathy, it will not directly affect your vision, however, regular checks are advised to keep the condition well monitored.


Pre-proliferative Retinopathy
This is the second stage. By this stage, new blood vessels have started to form in the retina and there are multiple points of bleeding.

Maculopathy
By this time, the macula (the most sensitive part of the retina) has been damaged.
Maculopathy, which leads to the sight threatening condition macula oedema, is when the blood vessels become more delicate and begin to leak. In the early stages, fluid from this can leak into the macula, which operates our immediate, straight-ahead vision, resulting in swelling and blurred vision. The macula is an extremely sensitive area of the retina and macula oedema is one of the most common causes of visual impairment that you can develop through diabetes.


During the maculopathy stage, the haemorrhage's, swellings and leakages of protein as seen in the background retinopathy stage all begin to affect the macula. Specifically, this affects our ability to see finer details, for example, fine print in books.


These leakages can be cured by laser eye treatment, but often, several years later, more is needed to ensure they are properly treated. The leaks are known as clinically significant macula oedema and it takes four to six weeks for the treatment to take any sort of effect. As the condition develops, if left untreated it could become very severe. Should severe maculopathy occur, it will be very difficult to treat.


Proliferative Retinopathy
This is the most advanced stage. Proliferative retinopathy begins by the blood vessels within the retina becoming blocked. As a result of the insufficient blood flow to the retina, new, abnormally sized blood vessels begin to grow. Because these new blood vessels are very delicate and fragile, as they grow they are easily broken and can leak or bleed. The vessels are so easily broken that even sudden head movements such as sneezing, or rapid eye movement during sleep can cause them to break. They leak into the vitreous, causing a vitreous haemorrhage. The vitreous is a jelly like substance, which fills the centre of the eye to support its structure and give it its shape. As these vessels grow, they stimulate the growth of further abnormal tissue and as they break, they will eventually cause scar tissue to form. As a result of this, eventually the retina will detach itself altogether from the back of the eye.

TREATMENTS

Laser Treatment
The type of laser treatment used to treat diabetic retinopathy is known as photocoagulation. Photocoagulation involves using a laser to burn away any abnormal blood vessels.
A course of photocoagulation involves one or more visits to a laser treatment clinic. Treatment is normally available on an out-patient basis. It is not usually painful, but you may feel an occasional sharp pricking sensation when certain areas of your retina are being treated.


Drops are put into your eyes to numb the surface but you may still find the procedure slightly uncomfortable.  A special contact lens is then placed on your eye to hold your lids open and to focus the laser beam on your retina. 


As time goes on and more laser sessions are needed, the treatment can become extremely painful. There is no entirely effective way of reducing all the pain, except a general anaesthetic.


Local anaesthetic injections in the operating theatre, or tablets that aid relaxation, may help a little. Sometimes the local anaesthetic injection takes away all the pain, sometimes it just reduces the pain slightly. The injection is not into the eye, but under it, at one side.  This type of anesthesia may be used when an extensive amount of laser is required, the patient has difficulty keeping the eye still, or the patient is very sensitive.


For patients where the treatment is extremely painful larger departments offer general anaesthetics, as these also have the advantage of allowing laser treatment to both eyes. To do this the department must have a laser that can be used in an operating theatre.


Your vision will be blurred after treatment, but this should return to normal after a few hours. If you have a lot of treatment on your eyes, it can cause them to ache. Over-the-counter (OTC) painkillers, such as paracetamol, should help ease the pain.


A 30 year old person with a lot of new vessels may need 6000 laser burns per eye, or even more, to prevent the new vessels growing. Other people usually need less. In patients with very severe disease so much laser may be required that the side vision becomes poor and driving unsafe: the aim of the treatment is to keep good central sight, that is sight looking straight ahead, which is need to read, work, and watch television.


Sometimes, photocoagulation can damage the outer retina. If this occurs, there is a chance that your night and peripheral vision (your ability to see to objects that are outside your direct gaze) may be affected.  More than 50% of people who have laser treatment for diabetic retinopathy notice some difficulty with their night vision, and 3% notice some loss of peripheral vision.


Vitreous Surgery
This is often required if:

•a large amount of blood has collected in the centre of the eye, obscuring your vision, or
•there is extensive scar tissue which is likely to cause, or has already caused, retinal detachment


The surgeon will make a small incision in your eye before removing the vitreous gel that sits in front of the retina. The vitreous gel is where the blood gathers.
Any scar tissue will be removed from your retina and, in some cases, the retina may be strengthened in position using tiny clamps. The vitreous gel will be replaced with a gas or liquid to help hold the retina in place. The gas or liquid will gradually be absorbed by your body, which will create new gel to replace the gel that was removed during surgery.


Vitreous surgery is usually performed under local anaesthetic and sedation. This means that you will feel no pain and have little or no awareness of the surgery being performed.  You should be able to go home on the same day or the day after your surgery.


For the first few days after surgery, you may be asked to wear an eye patch so that you can gradually make more and more use of your eye. This is because activities such as reading and watching television can quickly tire your eye.


Following vitreous surgery, it is normal to have blurred vision for several weeks. This should begin to improve gradually, though it may take several months before your vision returns to normal.


PREVENTION
To prevent or slow the progression of diabetic retinopathy, it is very important to keep your blood sugar level as close to normal as possible. 


Having high blood pressure (hypertension) can make the blood vessels in your eyes more vulnerable to damage, increasing your risk of developing advanced diabetic retinopathy.  The most effective way of preventing high blood pressure is to eat a healthy, balanced diet, including plenty of fruit and vegetables (at least five portions a day), and to take regular exercise (at least 30 minutes five times a week).


If diabetic retinopathy is diagnosed and treated at an early stage, the outlook for the condition is good. Research has found that treatment can prevent severe vision loss in 90% of cases of diabetic retinopathy. 


I hope (if you are still awake after reading all of that) that the post has answered a few questions about what Retinopathy is and what is involved in the treatment available. 


Some useful websites are:
http://medweb.bham.ac.uk/easdec/Information_for_patients.html
http://www.nhs.uk/Conditions/Diabetic-retinopathy/Pages/Introduction.aspx
http://www.youreyeguide.co.uk/retinopathy/index.html

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