Laser light (shown in yellow) is shone into the eye through a small contact lens, and makes small burns on the retina.
Laser treatment is the main treatment of retinopathy. In addition, Avastin injections will often be needed.
It is usually carried out in a darkened room
in clinic. Anaesthetic drops are dropped into your eye, a contact
lens is placed on your eye, and you have to sit at a laser slit lamp.
This is virtually the same machine as that used for the regular examination,
but a laser has been added on.
Each treatment is slightly different, depending
on the condition of the eye. Laser is simply a highly focused and powerful
light, where the light rays are all of the same type. Therefore
it can be pointed at one spot on the retina very accurately. Each bright
flash lasts 0.05-0.02 seconds.
The
commonest laser is Argon Green, wavelength 530nm, but
other wavelengths can be used and most are equally effective. Other
types of light were used before laser was introduced.
It is naturally uncomfortable having to
keep still whilst a doctor flashes a very bright light into the
eye.
Enlarge a common type of laser for maculopathy (burns are shown white for illustration)
This is also discussed here.
An average of 100 burns are needed, but this varies from very few
to 250. This type of laser is not particularly painful, and you notice
a bright slightly painful flash, and maybe slight stinging. You will
be asked to look in a certain position at different times.
After each session your sight may be dim or
blurred, and this improves over a few days. After the treatment,
some people, those with healthier eyes, may notice little black marks
in their vision if they look at a white background, and this starts
to fade months after the laser.
You may need treatment now and again. It can take
3-6 months before for the leakage in the retina to reduce; sometimes
proliferative retinopathy may develop as well, which will also need
laser (1200 plus burns).
Doctors are recommending less intensive laser
than was used previously....the doctor may recommend several laser
sessions ...but the results are getting better.
Just as important as the laser is controlling
the blood pressure to below 130/80 if possible, control of the diabetes
(fasting blood sugars of about 6mmol/l, HbA1c of 6.5% or below),
and not smoking. See below.
Here is a patient 2006 (left
photo) treated
with laser the next week, who at the same time started to improve
his diabetic control, lose weight, and lower his blood pressure.
The right
photo is after treatment in 2007. Below is same photo
a little smaller.
before laser (left), and one year after laser (right)...the
exudates (white areas) have disappeared
they do not seem to
have a significant permanent benefit for most patients.
Regular Avastin injected monthly
usually reduces macular oedema and improves vision in ~50% of patients
with macular oedema.
Laser for proliferative retinopathy or severe
pre-proliferative
enlarge laser for proliferative retinopathy (white for illustration)
The laser is applied the same way, usually through a slit lamp in the clinic.
Each treatment is often 1200 burns or more. Much more in one session may cause
inflammation of the eye, and too little too little an effect.
The side or 'peripheral' retina is lasered, not the centre;
this is the main difference of laser for proliferative retinopathy as opposed
to maculopathy above. NEJM 11
The downside of this treatment includes the discomfort. At first
the treatment sessions are unpleasant, with stinging flashes.
After the laser your sight may be blurred, and the eye may ache for days
after the treatment. If the eye still aches after a week, anti-inflammatory
drops may be helpful.
After the laser some people notice spots in their side vision if they look
at anything with a white background. This fades (you are 'seeing' the tiny
burns). Other people notice flashes of light at night.
Laser is need to stop the new vessels growing, but it does affect your sight.
You may notice glare, that is difficulty seeing in sunlight. You may also notice
difficulty seeing and driving at night. These are particular problems everyone
who has had a lot of laser notices. Wearing a peaked hat may be helpful, as
may tinted glasses, or glasses that change colour in bright weather.
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.
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.
The 'up' side of this laser is that the treatment nearly always works, although
several treatments may be needed, and further treatments may be needed over
the following months and years. An individual laser session only has a very
marginal effect on vision.
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.
If the proliferation is very aggressive, intravitreal avastin will
help, in addition to laser. It always shrinks the new vessels, but unless there
has been a lot of laser treatment given, the new vessels always recur. We are
learning how to use this and other anti-VEGF treatment, and each ophthalmologist
uses it differently. (At present at Good Hope we have no funding so cannot
use it.).
Without laser proliferative retinopathy is often blinding, so both patients
and doctors may be left with little alternative to enduring and carrying out
this often unpleasant treatment. Again, control of diabetes as for maculopathy
above is very helpful where possible in the long term.
In the short term, improving control
from mediocre (say HbA1c 9%) to good (say (6.5%) may encourage unexpected growth
of the new vessels, needing laser. This is discussed.
However, the improved control is still needed in the long term, and most
people are advised to achieve good control even if that means extra laser in
the next 2 years, because in the longer term (after 2-3 years) research
has shown good control reduces eye and other problems.
Laser for pre-proliferative (non-proliferative) retinopathy
Sometimes laser is needed for pre-proliferative
retinopathy: the treatment is similar to that of maculopathy and proliferative
retinopathy. Nearly all eyes with severe pre-proliferative retinopathy should
be lasered. Eyes with mild pre-proliferative do not need laser; eyes in between
often do need laser.
Ideally laser will be carried out before there is macular
oedema.
The lower the better in macular oedema, as long as you feel well.
An ideal pressure
is below 115 (systolic, first number) for healthy people. <120 is is only suitable for new/well diabetes patients 2012. Otherwise slightly higher as above.
Home
monitoring blood pressures should be 10mmHg (systolic) and 5mmHg (diastolic)
lower see than
these 'clinic' pressures.
HbA1c
7.5-6.5% or
less (see graph) with very few or preferably no hypos. These (or slightly
lower) levels are the best to prevent complications
<7.5 for insulin users; <6.5 if not using insulin and have good
health. Problems with intensive control.
If hypos develop, seek expert
advice from your diabetes nurse/doctor.
if your HbA1c is high (say 11%), then the next step may be to achieve
9%....in other words, and any improvement is helpful, gradually reaching
lower levels above.
sudden decrease
in HbA1c
A
sudden improvement in
control (HbA1c drop of 3%) will lead to a temporary rapid increase
in progression of retinopathy: laser may be needed.
Good control is important
in the longer term, that is after about 2 years. When people who control
their diabetes well will be better off after this period. See
A temporary increase in retinopathy is
most common when starting insulin for the first time, especially if
the diabetes is very badly controlled when you start the insulin.
cholesterol
<4.5 mmol/l, and statins recommended
for most adult patients with diabetes whatever the cholesterol.
statins are recommended whatever the cholesterol,
if well tolerated age>40y
A
fibrate such as fenofibrate may
be advisable in
every person with exudative maculopathy. They reduce retinopathy
progression 40% (Fenofibrate 200mg od) Field
Study. We now recommend these for all adult patients, and
they can be used in addition to a statin.
Insulin pumps generally
produce better control still, but are harder to use.
education
everyone with diabetes should attend
an education course, such as DAFNE (insulin)
, DESMOND (type
2 at diagnosis), or XPERT (type
2). Primary Care Trusts are obliged to send you on such a course, but
very few patients have ever attended one. If you have not been on one,
discuss this with your diabetic team. Get a diabetes buddy.
sleep apnoea
this contributes to macular oedema and loss of sight
(Schwartz, 2006), and many
serious problems.
It is common in
diabetes, particularly if you are overweight. Do you have sleep apnoea?
Rosiglitazone and pioglitazone should not be used
if there is significant retinopathy, and certainly not if macular oedema
is present, as they
increase macular oedema and fluid retention. Case
49. Lirglutadite
and Exenatide are drugs that can be used instead low also lower weight
(they are injections.)
hypoglycaemia
insulin users need to avoid serious hypoglycaemia.
Expert help is usually needed if episodes are severe/frequent. See
