Definition of diabetic retinopathy
If diabetes is not or poorly controlled high blood glucose levels can lead to damage of the small capillary blood vessels of the retina. These damages can cause complete blindness of both eyes if an appropriate therapy is not started in time.
When will the diabetic be aware of this damage of the eyes?
In the beginning capillary damage does not lead to interference of the vision. When it comes to advanced closures of the blood vessels or swellings with deposits of fat in the visual centre or when proliferations lead to bleeding into the vitreous body then diabetics will be aware of impaired vision. This process is not completely reversible but vision can be improved.
Appearance of retinopathy
Differences are enormous between type 1 and type 2 diabetics. Type 1 diabetes normally is diagnosed at an early stage. Therefore damage of the retina appears normally not earlier than 10 years after manifestation of diabetes. For type 2 diabetics it is a fact that 20% of all patients have already a diabetic retinopathy when diagnosed.
Up to 50% of all diabetics do no even know about their disease. So it is common that a routine check of the eyes leads to the diagnose diabetes by discovering diabetic retinopathy. In Austria there are about 200.000 non-diagnosed diabetics and therefore up to 40.000 patients already suffering from diabetic retinopathy without knowing it.
Diagnosis of retinopathy
Damage of the retina can only be diagnosed when the eye ground is checked with pupil enlarged. Every diabetic should undergo a check of the eye ground at the ophthalmologist once a year even if the vision is good. But also every non-diabetic should check the eyes regularly to ensure their health.
Alterations of the eye ground
The first apparent alteration are small, baggy dilatations of the capillaries, so-called “micro-aneurysms”. Microaneurysms are relatively harmless, they do not interfere with vision and can disappear spontaneously without any treatment. This happens especially in cases of good control of the blood glucose.
Beside a micro-aneurysm bleedings, swellings and crystal deposits of fats can occur.
These damages lead to impaired vision if occurring in the visual centre. This is called diabetic maculopathy or a “clinical significant diabetic macula oedema”.
Advanced closures of capillaries of the peripheral retina stay undetected until this leads to bleedings into the vitreous body. This proliferative retinopathy needs immediate treatment to avoid complete blindness.
Medical checks after diagnose of retinopathy
Retinopathy can be documented by photographs. This eases the control of the progression and aggravations of the condition can be detected quicker. At diabetic maculopathy or suspect of proliferations fluorenscencee angiography is performed. A colorant is injected into the vein which reaches after some seconds the blood vessels of the eye. The coloured pictures are then photographed by using special filters.
On these black and white pictures micro-aneurysms, closures of capillaries, areas of oedema and proliferations can be detected. Swelling of the macula, the oedema of the macula, can be measured by means of optical coherence tomography (OCT). A weak laser shot helps to show a cut view of the retina.
Several of these pictures lead to an exact map of the retina where areas of oedema are marked with colours.
What happens after diagnosis of a retinopathy?
If retinopathy is detected together with primary diagnose of diabetes there is a risk of deterioration despite therapy of diabetes. Regular checks in short intervals are strongly required.
If retinopathy is detected after many years of diabetes which is good controlled the risk of deterioration is lower. Regular checks should be performed nevertheless to ensure appropriate treatment in time.
When is a retinopathy treated by the ophthalmologist?
A retinopathy is treated when vision is threatened or reduced through a swelling of the retina in the area of the macula or if there are proliferations.
Treatment of the retinopathy
The ophthalmologist will contact the general practitioner of the patient to try together optimization of blood sugar and pressure. If proliferations of the retina were found obliteration of the peripheral areas of the retina, a “panretinal laser coagulation” has to be performed avoiding the visual centre and the optic nerve. The majority of the retina is this way obliterated leading to exsiccation of the proliferations. Even after a complete panretinal coagulation bleedings into the vitreous body can occur, but they are not so severe and will be sipped quickly.
If a swelling of the middle part of the retina, the „macula oedema“, was detected a gentle coagulation (“focal coagulation”) will be performed in that area. After that the oedema will disappear after some months and deposits of fat will be prevented.
Vision can be limited after the surgery for some days because laser surgery can also cause some swelling.
Other methods of treatment
If laser coagulation did not succeed other surgical methods like vitrectomy (elimination of vitreous body) or – in future – injections of medication directly into the eye can be performed.
This medication inhibits a growth hormon which is produced increased at retinopathy and leads therefore to a reduction of the retina swelling and the proliferations.
Early diagnose of diabetes is of high importance. This can be ensured by regular checks by the general practitioner as type 2 diabetes does not lead to any symptoms in the beginning. If diabetes is already diagnosed more regular checks are required (blood glucose control, blood pressure, blood fats, kidney function, heart). Regular check of the eye ground by an ophthalmologist is recommended.
Diabetics should try to learn as much as possible about diabetes and late complications. Big hospitals and self care groups of patients provide regular trainings for diabetics to teach how to live with diabetes and how to prevent late complications like retinopathy or kidney failure.