Diabetic retinopathy is a complication of diabetes, caused by high blood sugar levels damaging the back of the eye (retina). It can cause blindness if left undiagnosed and untreated.
However, it usually takes several years for
diabetic retinopathy to reach a stage where it could threaten your sight. To minimise the risk of this happening, people with
diabetes should:
- ensure
they control their blood sugar levels, blood pressure and cholesterol
- attend
diabetic eye screening appointments – annual screening is offered to all
people with diabetes aged 12 and over to pick up and treat any problems
early on.
How diabetes can affect the eyes
The retina is the light-sensitive layer of cells at
the back of the eye that converts light into electrical signals. The signals
are sent to the brain and the brain turns them into the images you
see.
The retina needs a constant supply of blood, which
it receives through a network of tiny blood vessels. Over time, a
persistently high blood sugar level can damage these blood vessels in
three main stages:
- tiny
bulges develop in the blood vessels, which may bleed slightly but do not
usually affect your vision – this is known as background retinopathy
- more
severe and widespread changes affect the blood vessels, including more
significant bleeding into the eye – this is known as pre-proliferative retinopathy
- scar
tissue and new blood vessels, which are weak and bleed easily, develop on
the retina – this is known as proliferative retinopathy and it can result in
some loss of vision.
However, if a problem with your eyes is picked up
early, lifestyle changes and/or treatment can stop it getting worse.
Schematic diagram showing the pathogenesis of diabetic retinopathy.
Am I at risk of diabetic retinopathy?
Anyone with type 1 diabetes or type 2 diabetes is potentially at risk
of developing diabetic retinopathy. You are at a greater risk if you:
- have had
diabetes for a long time
- have
a persistently high blood sugar (blood glucose) level
- have high blood pressure
- have high cholesterol
- are
pregnant
- are
of Asian or Afro-Caribbean background.
By keeping your blood sugar, blood pressure and
cholesterol levels under control, you can reduce your chances of developing diabetic
retinopathy.
Symptoms of diabetic retinopathy
You won't usually notice diabetic retinopathy in
the early stages, as it doesn't tend to have any obvious symptoms
until it is more advanced.
However, early signs of the condition can be picked
up by taking photographs of the eyes during diabetic eye screening. You must contact your doctor/ GP or diabetes care team immediately
if you experience:
- gradually
worsening vision
- sudden
vision loss
- shapes
floating in your field of vision (floaters)
- blurred
or patchy vision
- eye
pain or redness.
These symptoms don't necessarily mean you have
diabetic retinopathy, but it's important to get them checked out. Don't
wait until your next screening appointment.
Schematic diagram showing the types of diabetic retinopathy.
Diabetic eye screening
Everyone with diabetes who is 12 years old or over is invited for eye screening once a year. Screening is offered because:
- diabetic
retinopathy doesn't tend to cause any symptoms in the early stages
- the
condition can cause permanent blindness if not diagnosed and treated
promptly
- screening
can detect problems in your eyes before they start to affect
your vision
- if
problems are caught early, treatment can help prevent or reduce vision
loss.
The screening test involves examining the back of
the eyes and taking photographs. Depending on your result, you may be advised
to return for another appointment a year later, attend more regular
appointments, or discuss treatment options with a specialist.
Reduce your risk of diabetic retinopathy
You can reduce your risk of developing diabetic retinopathy, or help prevent it getting worse, by:
- controlling
your blood sugar, blood pressure and cholesterol levels
- taking
your diabetes medication as prescribed
- attending
all your screening appointments
- getting
medical advice quickly if you notice any changes to your vision
- maintaining
a healthy weight, eating a healthy, balanced diet, exercising regularly and stopping smoking.
Treatments for diabetic retinopathy
Treatment for diabetic retinopathy is only
necessary if screening detects significant problems that mean your vision is at
risk.
If the condition hasn't reached this stage, the
above advice on managing your diabetes is recommended. The main treatments for more advanced diabetic
retinopathy are:
- laser
treatment
- injections
of medication into your eyes
- an
operation to remove blood or scar tissue from your eyes.
Stages of diabetic retinopathy
Diabetic retinopathy
develops in stages over time. If you're diagnosed with diabetic retinopathy
after diabetic eye screening, lifestyle changes
and/or treatment can reduce the chances of the problem progressing. The main stages of diabetic retinopathy are
described below. You won’t necessarily experience all of these.
Stage
one: background retinopathy
This means that tiny bulges (microaneurysms) have appeared in the blood vessels in the back of your eyes (retina), which may leak small amounts of blood. This is very common in people with diabetes. At this stage:
- your
sight isn't affected, although you are at a higher risk of developing
vision problems in the future
- you
do not need treatment, but you will need to take care to prevent the
problem getting worse – read more about preventing diabetic retinopathy
- the
chances of it progressing to the stages below within three years is
over 25% if both of your eyes are affected.
Stage
two: pre-proliferative retinopathy
This means that more severe and widespread changes
are seen in the retina, including bleeding into the retina. At this stage:
- there is
a high risk that your vision could eventually be affected
- you'll usually be advised to have more frequent screening appointments every three or six months to monitor your eyes.
Stage
three: proliferative retinopathy
This means that new blood vessels and scar tissue
have formed on your retina, which can cause significant bleeding and lead
to retinal detachment (where the retina pulls away from
the back of the eye). At this stage:
- there is
a very high risk you could lose your vision
- treatment will
be offered to stabilise your vision as much as possible, although it won't
be possible to restore any vision you have lost.
Diabetic
maculopathy
In some cases, the blood vessels in the part of the
eye called the macula (the central area of the retina) can also become leaky or
blocked. This is known as diabetic maculopathy. If this is detected:
- there is
a high risk that your vision could eventually be affected
- you
may be advised to have more frequent specialised testing to monitor your
eyes
- you
may be referred to a hospital specialist to discuss treatments that
can help stop the problem getting worse.
Which stage am I at?
If you have had a diabetic eye screening test, you will be
sent a letter stating that you have one of the following:
- no retinopathy – this means no signs
of retinopathy were found and you should attend your next screening
appointment in 12 months
- background retinopathy –
this means you have stage one retinopathy and should attend your next
screening appointment in 12 months
- degrees of referable retinopathy –
this means you have stage two or three retinopathy, or diabetic
maculopathy, and should have more frequent tests or talk to a specialist
about possible treatments.
Treating diabetic retinopathy
Diabetic retinopathy
usually only requires specific treatment when it reaches an advanced stage and
there's a risk to your vision.
It is typically offered if diabetic eye screening detects stage
three (proliferative) retinopathy, or if you have symptoms caused by diabetic
maculopathy. At all stages, managing your diabetes is crucial.
Managing
your diabetes
The most important part of your treatment is to keep your diabetes under control. In the early stages of diabetic retinopathy, controlling your diabetes can help prevent vision problems developing.
In the more advanced stages, when your vision is
affected or at risk, keeping your diabetes under control can help stop the
condition getting worse.
Treatments
for advanced diabetic retinopathy
For diabetic retinopathy that is threatening or affecting your sight, the main treatments are:
- laser treatment – to
treat the growth of new blood vessels at the back of the eye (retina) in
cases of proliferative diabetic retinopathy, and to stabilise some cases
of maculopathy
- eye injections – to
treat severe maculopathy that's threatening your sight
- eye surgery–to
remove blood or scar tissue from the eye if laser treatment isn't
possible because retinopathy is too advanced.
Laser treatment
Laser treatment is used to treat new blood vessels
at the back of the eyes in the advanced stages of diabetic retinopathy. This is
done because the new blood vessels tend to be very weak and often cause
bleeding into the eye.
Treatment can help stabilise the changes in
your eyes caused by your diabetes and stop your vision getting any worse,
although it won't usually improve your sight. Laser treatment:
- involves
shining a laser into your eyes – you will be given local anaesthetic drops to
numb your eyes; eye drops are used to widen your pupils and special
contact lenses are used to hold your eyelids open and focus the laser onto
your retina
- normally
takes around 30-40 minutes
- is
usually carried out on an outpatient basis, which means you
won't need to stay in hospital overnight
- may require more
than one visit to a laser treatment clinic
- is not
usually painful, although you may feel a sharp pricking sensation when
certain areas of your eye are being treated.
Side effects
After treatment, you may have some side effects for
a few hours. These can include:
- blurred
vision – you will not be able to drive until this passes, so you'll
need to arrange for a friend or relative to drive you home, or take
public transport
- increased
sensitivity to light – it might help to wear sunglasses
until your eyes have adjusted
- aching
or discomfort – over-the-counter painkillers, such as paracetamol, should help.
Possible complications
You should be told about the risks of treatment in
advance. Potential complications include:
- reduced
night or peripheral (side) vision – some people may have to stop
driving as a result of this
- bleeding
into the eye or objects floating in your vision (floaters)
- being
able to "see" the pattern made by the laser on the back of your
eye for a few months
- a small,
but permanent, blind spot close to the centre of your vision.
You must get medical advice if you notice that your
sight gets worse after treatment.
Eye injections
In some cases of diabetic maculopathy, injections
of a medicine called anti-VEGF may be given directly into your eyes to prevent
new blood vessels forming at the back of the eyes.
The main medicines used are called ranibizumab
(Lucentis) and aflibercept (Eylea). These can help stop the problems in
your eyes getting worse, and may also lead to an improvement in your vision. During treatment:
- the
skin around your eyes will be cleaned and covered with a sheet
- small
clips will be used to keep your eyes open
- you will
be given local anaesthetic drops to numb your eyes
- a very
fine needle is carefully guided into your eyeball and the
injection is given.
The injections are usually given once a month to
begin with. Once your vision starts to stabilise, they will be stopped or given
less frequently. Injections of steroid medication may sometimes be
given instead of anti-VEGF injections, or if the anti-VEGF injections
don't help.
Risks and side effects
Possible risks and side effects of anti-VEGF injections include:
- eye
irritation or discomfort
- bleeding
inside the eye
- floaters
or a feeling of having something in your eye
- watery
or dry, itchy eyes.
There is also a risk that the injections could
cause blood clots to form, which could lead
to a heart attack or stroke. This risk is small, but it should
be discussed with you before you give your consent to treatment. The main risk with steroid injections is increased
pressure inside the eye.
Eye surgery
Surgery may be carried out to remove some of the vitreous humour from the eye. This is the transparent, jelly-like substance that fills the space behind the lens of the eye. The operation, known as vitreoretinal surgery, may be needed if:
- a
large amount of blood has collected in your eye
- there's
extensive scar tissue that's likely to cause, or has already
caused, retinal detachment.
During the procedure, the surgeon will make a small
incision in your eye before removing some of the vitreous humour, removing any
scar tissue and using a laser to prevent a further deterioration in your
vision.
Vitreoretinal surgery is usually carried out under
local anaesthetic and sedation. This means you will not experience any pain or
have any awareness of the surgery being performed.
After the procedure
You should be able to go home on the same day or the day after your surgery. For the first few days, you may need to wear a patch over your eye. This is because activities such as reading and watching television can quickly tire your eye to begin with.
You will probably have blurred vision after the
operation. This should improve gradually, although it may take several months
for your vision to fully return to normal. Your surgeon will advise you about any activities
you should avoid during your recovery.
Risks and side effects
Possible risks of vitreoretinal surgery include:
- developing
a cataract
- further
bleeding into the eye
- retinal
detachment
- fluid
build-up in the cornea (outer layer at the front of the eye)
- infection
in the eye.
There is also a small chance that you will need
further retinal surgery afterwards. Your surgeon will explain the risks to you.
Preventing diabetic retinopathy
You can reduce your risk
of developing diabetic retinopathy, or help stop
it getting worse, by keeping your blood sugar levels, blood pressure and
cholesterol levels under control. This can often be done by making healthy lifestyle
choices, although some people will also need to take medication.
Healthy
lifestyle
Adopting a few lifestyle changes can improve your
general health and reduce your risk of developing retinopathy. These include:
- eating a healthy, balanced diet – in
particular, try to cut down on salt, fat and sugar
- losing weight if you are
overweight – you should aim for a BMI of 18.5-24.9; use the BMI calculator to work out your
BMI
- exercising regularly – aim to do at least 150 minutes
of moderate-intensity activity, such as
walking or cycling, a week; doing 10,000 steps a day can be a good
way to reach this target
- stopping smoking if you smoke
- not exceeding the recommended alcohol limits – men
and women are advised not to regularly drink more than 14 alcohol units a week.
You may also be prescribed medication to help
control your blood sugar level (such as insulin or metformin), blood pressure
(such as ACE inhibitors) and/or cholesterol level (such as statins).
It can be easier to keep your blood sugar
levels, blood pressure and cholesterol levels under control if you know what
level they are and monitor them regularly.
The lower you can keep them, the lower your chances of developing retinopathy are. Your diabetes care team can let you know what your target levels should be.
Blood sugar
If you check your blood sugar level at home, it
should be 4 to 10mmol/l.
The level can vary throughout the day, so try to check it at different times.
The check done at your GP surgery is a measure of
your average blood sugar level over the past few weeks. You should know this
number, as it is the most important measure of your diabetes control. It is called HbA1c, and for most people with
diabetes it should be around 48
mmol/l or 6.5%.
Blood pressure
You can ask for a blood pressure test at your GP surgery, or you can buy a blood pressure monitor to use at home. Blood pressure is measured in millimetres of mercury (mmHg) and is given as two figures.
If you have diabetes, you will normally be advised to
aim for a blood pressure reading of no more than 140/80mmHg, or less than 130/80mmHg if you have diabetes
complications, such as eye damage.
Cholesterol
Your cholesterol level can be measured with a
simple blood test carried out at your GP surgery. The result is given
in millimoles per litre of blood (mmol/l). If you have diabetes, you'll normally be advised to
aim for a total blood cholesterol level of no more than 4 mmol/l.
Regular
screening
Even if you think your diabetes is well controlled,
it is still important to attend your annual diabetic eye screening appointment, as
this can detect signs of a problem before you notice anything is wrong.
The earlier that retinopathy is detected, the
greater the chance of effectively treating it and stopping it getting
worse. You should also contact your doctor or diabetes care
team immediately if you develop any problems with your eyes or vision, such as:
- gradually
worsening vision
- sudden
vision loss
- shapes
floating in your field of vision (floaters)
- blurred
vision
- eye
pain or redness.
These symptoms do not necessarily mean you have
diabetic retinopathy, but it's important to get them checked out straight away.
Source: NHS Choices