Diabetic Retinopathy is a serious pathological condition in which small blood vessels of the retina, the thin membrane of nerve cells and the internal layers in the back of the eye, are altered by the constant high blood sugar. These capillaries tend to ooze fluid (edema) or blood (bleeding) or may become blocked (ischemia) with serious consequences on eyesight.
Who is most at risk?
Diabetic retinopathy is the main cause of blindness in adults between the age of 20 and 60 years.
After 15 years of illness, 40% of diabetics have abnormalities of the retinal microcirculation, even before the patient is aware of them. Pregnancy, high blood pressure and smoking can worsen the situation.
The diagnosis and early treatment of diabetic retinopathy can prevent vision loss.
It is essential therefore, to perform an eye examination and test the ocular fundus at least once a year, because in the beginning the symptoms may be absent, even with existing alterations.
What are the symptoms of diabetic retinopathy?
In the early stage of diabetic retinopathy, there may be no symptoms.
However, it is very important not to wait to have problems to be examined.
Rapid changes in blood glucose values, even in the absence of retinopathy, can cause transient blurring of vision.
If the macula, the central most part of the retina, is filled with liquid part (edema) and blood, due to diabetic disease, the vision becomes blurred, and the visual recovery is even more difficult after the treatment.
If you suddenly see black spots, floaters or complete clouding of the field of vision, there may be internal bleeding due to the growth of new abnormal and fragile blood vessels which leak fluid and blood to the retina and optic nerve. This stage is known as proliferative diabetic retinopathy.
It is important to urgently see the doctor if you notice your vision worsening, if It lasts for more than a few days and is not associated with a glycemic overhang.
What are the causes of diabetic retinopathy?
There are two types of diabetic retinopathy: proliferative (RDP) and non-proliferating (NPDR). The NPDR, formerly known as background retinopathy, is the initial stage of the disease.
In the early stages of diabetic retinopathy, the blood vessels dilate and can lose fluids that accumulate in the retina, causing swelling of the macula and the formation of solid deposits causing a distorted view. Although these liquids can be reabsorbed, sometimes they form "solid" deposits which in turn can adversely affect the view.
Subsequently, the vessels will begin to bleed causing retinal hemorrhages.
The small blood vessels of the retina begin to lose blood and fluid. The fluid flows in an uncontrolled manner from the vessels damaged by diabetes. It causes the swelling of the retina (edema) and the formation of deposits. Many people with diabetes have mild NPDR, which usually does not involve loss of vision. The eyesight on the other hand, is reduced when the macula, which allows us to appreciate the fine details, is damaged. The macula may swell due to edema or loss of blood due to ischemia. Another symptom of this stage is the distortion of the images. The RDP is determined by the growth of new abnormal vessels on the retina and optic nerve.
The non-proliferative stage of the disease is characterized by a drastically reduced blood flow in the retina, due to the damage of the normal blood vessels. This phenomenon results in an oxygen demand which the retina itself attempts to satisfy inducing new blood vessels to form and proliferate.
However, these vessels are fragile and immature. They can bleed easily and cause internal bleeding, called emovitreo. The eyesight in these cases can be reduced sharply, until the blood is reabsorbed either spontaneously or surgically. The RDP leads to a progressive traction on the retina with distortion and permanent reduction of vision.
In more severe cases, new abnormal vessels grow on the surface of the iris which is the colored part of the eye, and where the eye fluid drains out of the eye. This means that the outflow of the aqueous humor is blocked causing neovascular glaucoma. It is a severe condition with important intraocular pressure elevation.
How to diagnose diabetic retinopathy?
The diabetic retinopathy diagnosis can be made only by an ophthalmologist, through:
-An examination of the fundus, after dilation of the pupil
-An Optical Coherence Tomography (OCT), a modern and non-invasive examination is essential in the diagnosis and provides a quantification of the problem. The OCT is an ultrasound which replaced ultrasound with a laser light. The amount of information gathered by the beam reflected by the eye is remarkably high. It can recognize structures measuring 7 thousandths of a millimeter.
-A retinal fluorescein angiography (FAG) can be recommended, especially in controversial cases.
Fluorescein angiography involves injecting a dye into the arm and taking photographs of the fundus to see the distribution of the dye out of the damaged vessels. This method rarely causes allergy. Diabetic women who are pregnant should consult an ophthalmologist within the first trimester, as retinopathy can worsen quickly during pregnancy.
What is the treatment of diabetic retinopathy?
-Prevention is the best treatment for diabetic retinopathy.
-Absolute control and constant monitoring of blood sugar reduces the risk of a significant visual loss.
-Consulting an eye specialist and treatment becomes necessary if it is an outbreak of solid deposit on the Macul or if it has become a proliferative retinopathy. In the case of macular edema, therapy is given through the combination of a laser treatment with intravitreal injection of anti-VEGF drugs.
-The edema is due to leakage of liquid or blood by damaged capillaries. The laser is used with the intention to close these capillaries favoring the reabsorption of the fluid.
-The anti-VEGF drugs are directed against a molecule, the growth factor of endothelial cells, responsible for the extravasation of fluid and blood from the damaged capillaries. These drugs (Avastin, Lucentis and Macugen) are injected directly into the eye with a puncture.
-It is not a real surgery, although it is often performed in the operating room. The risks in this process are very low, but include intraocular infections, and should be minimized.
These two therapeutic possibilities thus act synergistically, preventing fluid exiting from the capillaries and facilitates the re-absorption of the previously leaked fluid, with good success.
However, the results of this therapeutic strategy depend largely on conditions in which the patient is involved.
The better the eyesight is before the operation, the higher the possibility to preserve and improve the vision. Most of the laser treatments require more than one injection to treat macular edema associated with diabetic retinopathy. In particular, the monthly intravitreal injections are usually repeated, until the edema completely disappears or until no difference can be seen in the treatment.
The proliferative stage of diabetic retinopathy is treated with the laser as well as with the injections. The rationale, however, is completely different. The new vessels of proliferative retinopathy are formed in response to a request for oxygen by the ischemic retina damaged by diabetes. To prevent this from happening, it is necessary to decrease this oxygen demand. The laser destroys the already damaged retina, preventing the release of substances that promote the growth of new vessels. This treatment refers to laser therapy targeted at the several hundred commercials, coagulates and all the peripheral retinal tissue, sparing the central retina. The PRP is usually performed in multiple sessions. It has the dual purpose of preventing the proliferative retinopathy in at-risk cases and inducing regression in now overt cases.
However, if you are in a situation already compromised and complicated by the presence of internal bleeding or retinal detachments, the only solution is surgery