What is Diabetic Retinopathy?
Diabetes is a disease, which
affects the small blood vessels of all the organs of
the body. As the disease progresses it inevitably
involves the microvascular architecture i.e. the
blood supply of the retina (sensory part of the eye)
also. This manifestation of diabetes is called as
To simplify – It is a disease of the blood vessels
of the retina due to diabetes.
What causes it & who are at risk?
The main cause is long
patients with diabetes (Type 1), upto 8% of
individuals will have this disease after 3 years
of diagnosis and 25% at 5 years, 60% at 10
years, and 80% of diabetics will have this eye
problem by 15 years.
In older type 2
diabetics up to 21% of patients have diabetic
retinopathy at the time of first diagnosis of
diabetes, and most develop some degree of
retinopathy over time.
Uncontrolled diabetes , High
blood pressure, High cholesterol, Kidney disease and
Low Haemoglobin worsen diabetic retinopathy.
What are the symptoms & signs?
It may be asymptomatic for a
Once the macula , i.e. the central part of the
retina develops swelling , there would be a
deterioration in eyesight.
If there is bleeding within and in front of the
retina, floaters would be seen or the vision may be
drastically reduced. Floaters is seeing black spots
or lines moving in front of the eye.
Once the central retina is detached the vision loss
becomes severe and chances of recovery even after
surgery become less.
How is it diagnosed?
It can be diagnosed by a
simple dilated eye examination to see the retina in
detail. If significant changes are found then
investigations like Fluorescein Angiography and
Optical Coherence Tomography may be done.
Fluorescein Angiography involves taking
photographs of the retina after injecting a dye in a
vein in the patient’s arm. The dye reaching the eye
helps to clarify the type and extent of disease,
including detail of abnormal vessels and leakage.
Optical Coherence Tomography : In this test
images of the retina are taken to show its
microscopic detail. So it can help detect any early
thickening of the retina in areas of leakage. The
type and amount of thickening can be delineated and
an assessment of any pull on the retina can also be
made. It is an excellent tool to follow up after
treatment to assess the effect of the treatment done
and need for re-treatment.
What is the treatment?
The gold standard of therapy
is Retinal LASER Photocoagulation.
LASER can help to prevent a bleed in the eye and
also decrease swelling of the retina. However, it
cannot usually restore vision lost due to the
retinal damage. It has to be appropriately timed.
The Lasers used for this purpose are Green & Red
Other options now available are injecting drugs like
steroids and AVASTIN into the eye. These drugs also
aim to reduce the swelling in the retina and help in
drying up of the abnormal blood vessels. These are
quite effective and can even improve vision in some
cases. A major drawback is the effect of these drugs
is time limited and many patients require
Combination therapy of LASER and injections is also
What are the surgical options?
Advanced cases with
non-resolving bleed (Vitreous Hemorrhage) in the eye
or retinal detachment require advanced microsurgery.
This involves highly complex Vitreo-Retinal surgical
Today with highly advanced technology, some amount
of visual recovery can be achieved in a large number
of advanced cases also.
What are the outcomes?
Cases which present early
and are adequately lasered generally maintain good
vision. A good control of diabetes is most important
to slow the progression of disease. A combination of
injectable drugs and laser has improved the outcome
in moderately advanced cases also. The outcome may
not be very good in advanced cases even after
surgery, however still some useful vision can be
What are the complications?
Complications of diabetic
retinopathy are non resolving swelling (oedema) of
the retina, bleeding into the eye and detachment of
Complications of LASER are minimal. In some cases
the swelling of the retina might increase initially,
but this also normalizes in most patients.
Complications of AVASTIN per se are also minimal ,
but the main risk is of infection during the
injection procedure. To prevent infection we
routinely perform the injection in our operation
theatre , taking all aseptic precautions.
Complications of steroid injection can again be
infection, rise in eye pressure (glaucoma) and
Complications of surgery can be repeat bleeding into
the eye or damage to the retina.
Any other information?
Most importantly to retard
the progression of diabetic retinopathy the
following parameters must be strictly maintained –
1. Strict blood sugar control . Maintain
Glycosylated Haemoglobin (HBA1C) < 7%. This test
reflects the sugar control over the past 3 months.
2. Control blood pressure
3. Rule out loss of protein in urine (
microalbuminuria) and treat kidney disease as far as
4. Reduce LDL cholesterol
5. Maintain Haemoglobin more than 12 gm %
Author: Sanjay Dhawan, New Delhi, India
Last updated on 31 May 2011