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Diabetic Retinopathy


About Diabetic Retinopathy

Diabetic Retinopathy & Your Eyes

Diabetes is one of the growing diseases in India. In 1995 nearly 135 million people had diabetes throughout the world; however, the World Health Organization (WHO) has estimated that in India, the number of adults with diabetes would be the highest for any part of the world: a startling 195 percent increase, from 19 million in 1995 to 54 million in 2025. India is poised to have the largest number of diabetes in the world by year 2020 hence we have to gear up to face this challenge where vision loss due to diabetes would be a major concern.

The central part of the retina is known as macula, and is the most important and sensitive area for us to see and read. In patients with diabetic retinopathy, if the damaged blood vessels leak fluid and lipids onto the macula, it results in a condition known as diabetic maculopathy, an important reason for blurring of vision in diabetics.

Diabetes is the most commonly treated disease & cause of concern as its prevalence has been rising steadily. People with diabetes are at risk of developing eye disease that can permanently damage their vision and even lead to blindness. Diabetes causes diabetic retinopathy as well as other disorders such as retinal arterial and venous occlusions. Diabetes can also result in early onset cataract formation, glaucoma and strokes affecting the optic nerve (anterior ischaemic optic neuropathy - AION).

What is Diabetic Retinopathy?

Diabetic retinopathy affects people with diabetes. All patients with diabetes will develop Retinopathy at some stage in their life – 80 % will develop at 20 years of the disease. The eye is like a camera with the lens in the front and the film behind celled the Retina on which the image falls to be transmitted to the brain. The high sugar level in the blood weakens and affects the functions of the capillaries (small blood vessels) in the retina (the back of the eye), resulting in diabetic retinopathy. When this happens, the capillaries cannot function normally and they start to form out pouchings – micro aneurysms that can result in small areas of bleeding seen in early disease classified as mild non proliferative diabetic retinopathy. The abnormal capillaries can also leak fluid containing proteins and fatty substances into the retina, causing swelling of the retina, known as macular oedema. The weakened capSillaries may collapse and close and  cause blood and oxygen supply to the area to fail, leading to ischaemia (Capillary non perfusion) and cell death of the affected this will in turn trigger the growth of new capillaries – NVD NVE to enables more blood and oxygen to be delivered to the affected retina. This stage of disease is called proliferative diabetic retinopathy. These new capillaries however are abnormal and weak. They can  rupture and bleed – vitreous hemorrhage  and cause sudden loss of vision. As they grow, scar tissue grows with them, which can exert fractional force on the retina, causing tractional retinal detachments with distortion or loss of vision.



Causes and Symptoms

How will I know if I have diabetic retinopathy?

Unfortunately, it remain a sympotomatic vision remains normal in the early stages of diabetic retinopathy and the diabetic individual can be totally symptom free. As the diabetic retinopathy advances, there may be a slow but progressive visual loss. Alternatively, there might be sudden visual loss with floaters because of bleeding inside the eye.

What increases the risk of developing diabetic retinopathy?

The most important risk factor is duration of diabetes. The longer the duration, the greater the likelihood of developing diabetic retinopathy. The next most important risk factor is blood sugar control. Several studies done  have shown that good sugar control not only prolongs the onset of diabetic retinopathy, it also controls the severity of the disease. Other risk factors include concurrent disease affecting other organs such as kidneys, nervous system, anaemia, high blood pressure, high cholestserol, eye surgery, cigarette smoking and pregnancy. All people with diabetes are at risk; during pregnancy, diabetic retinopathy may worsen.


How is it Diagnosed

Diabetic Retinopathy- Complications that harm your eyes

Unfortunately, the complications caused by diabetes do not end with background and proliferative diabetic retinopathy. If it were so, ophthalmologist might not see so much havoc wrought by diabetes. A diabetic patient can prevent most of his complications if he educates himself about the disease and its deleterious effects on various body parts. A diabetic who knows the most lives the longest.

This new vessel growth in PDR is the retina’s method of coping with the closing of its own blood vessels and the loss of nourishment.

But the problem is that when new blood vessels do develop, they are never any good; like the natural vessels we have they are, in fact, dangerous to the eye. They do not nourish the retina properly, and they may cause other problems.

One problem is bleeding into the vitreous cavity – called vitreous hemorrhage. A second problem is the growth of scar tissue on the retina that can pull the retina off the back wall of the eye-called a traction retinal detachment.

A third problem occurs when the abnormal new blood vessels grow on the iris, the colored part of the eye, rather than just on the retina. This condition is called rubeosis iridis. When these blood vessels grow on the iridis, they may close off the normal flow of fluid out of the eye and cause the pressure in the eye to rise. The high pressure, called neovascular glaucoma sometimes causes permanent changes, resulting in visual loss, pain.

It is very important to understand that the closing of retinal blood vessels and the growth of new blood vessels may occur without any noticeable change of vision. When vitreous hemorrhage occurs, there is a sudden blurring of vision and the appearance of spots that look like strings, spiderwebs, or insects that seem to float in front of the eye. It is often helpful for the patient who develops a vitreous hemorrhage to remain in a sitting position so that gravity can help settle the blood to the lower parts of the viteous cavity.

Once the blood settles, panretinal laser photocoagulation can be done. Laser cannot make the blood disappear, but it can prevent more bleeding and expedite the clearing of a hammerage. The vitreous hemorrhage that is present usually disappears with time – we wait for approximately 1 to 3 months

If there is so much viteous hemorrhage that laser treatment is not possible or if the blood does not disappear on its own, it can be removed with an operation called a Vitrectomy. The blood-filled vitreous gel is removed. The lack of vitreous gel does not affect the function of the eye. This operationsis done through a key hole ½ mm opening in the  white part of the eye.

When a retinal detachment occurs, the patient will notice a shadow or very large dark area in the vision. When the retinal detachment extends to the macula, the dark shadow will be straight ahead and vision will be very poor. The abnormal new blood vessels and scar tissue also can cause visual loss because they can wrinkle the retina - Metamorphopsia

The only way the patient can regain any vision is for the retina to be reattached and the blood vessels and scar tissue to be removed from the surface of the retina. This is accomplished by Vitrectomy surgery. The surgeon removes the vitreous gel from the eye so that it stops pulling on the retina and the traction can be released. Some times gases or silicon oil are injected as vitrious substitute for retinal tamponard. The surgeon may remove the scar tissue from the surface of the retina so that there is no wrinkling of the retina.

Laser may be used to prevent late development of abnormal new vessels and rubeosis. The surgeons also laser inside the eye to seal any tears of the retina. If there are tears in the retina, the surgeon places a large air bubble in the eye to press the retina completely against the back wall of the eye while the laser treatment takes hold. In time, the air bubble will disappear and be replaced by the eye’s own fluid.

“What is important is to remember that once retinopathy starts, even the control of blood sugar will not stop it. This makes it vital for people to have an eye examination once a year not just when their sugar is high but even when it has been controlled.”


What can I do to prevent diabetic retinopathy or stop its progress?

Most importantly, you should ensure good control of the blood sugar levels. Ideally, the HbA1c levels should be less than 7.0% and the average blood glucose level should be less than 80mg/L. This can be achieved through compliance with treatment, regular visits to the doctors and being careful with food and a good exercise regimen.

Can diabetic retinopathy be cured once it develops?
No. In the early stage, with very minimal changes and good blood sugar control, it is possible to stabilise the diabetic retinopathy.
Once there is advanced diabetic retinopathy, the aim of the treatment will be to preserve what vision is left. Unfortunately, damaged retinal  nerve cells cannot be replaced as nerve cells cannot reproduce themselves.

The mainstay of treatment for severe diabetic retinopathy is laser photocoagulation. This involves creating tiny burns on the retinal surface to control the disease process. However, if there is very advanced diabetic retinopathy with scar tissue formation and retinal detachment, surgery to remove the scar tissue and return the retina back to its original position will have to be considered.

They are very effective in reducing vision loss from this disease. In fact, even people with advanced retinopathy have a 90 per cent chance of keeping their vision provided they get treatment before the retina is severely damaged.

Can diabetic retinopathy lead to blindness?

YES! Due to tractional retinal detachment affecting both eyes as diabetes affects both your eyes due to the poison in your blood.

Once there is damage to the nerve cells of the retina, these cells cannot reproduce themselves and vision will be permanently affected.

So, what should a person with diabetes do in terms of his/her eye care?

Every diabetic patient should meet his eye surgeon as often as he meets his diabetologist . It is important to go for a yearly diabetic retinopathy screening. This can be achieved with photography of the back of the eye, i.e. the retina. The photograph will be able to document the presence or absence of diabetic retinopathy. Fundus flourescien  angiography is the angriophuy of the retina showing us leaking vessels and helping us to guide our laser treatment accordingly.


How is it Treated

There are two treatments for diabetic retinopathy.

These two treatments are laser surgery and vitreous surgery, It is important to remember that though both of these treatments are very successful, they do not cure diabetic retinopathy.

Lasers in Diabetic Retinopathy


Laser surgery can be helpful for the treatment of diabetic retinopathy. The laser beam is a high-energy light which is collimated into fine focus that turns to heat when it is focused on the parts of the retina to be treated.

The laser treatment does not affect the outer eye – the cornea or the lens . The physician uses drops to widen pupil, then aims the beam through the open pupil directly at the retina.
In background diabetic retinopathy (BDR), the laser heat either seals the leaking blood vessels of the macula or reduces their leakage and allows the macula to dry. It is like sealing the leak by welding your water pipe.

In proliferative diabetic retinopathy (PDR), the laser destroys the diseased portions of the retina to stop the growth of new blood vessels by reducing the formation of various factors which lead to neovasularisation – VEGF – vascular endothelial growth factor.

Initially a special test called fluorescein angiography may be done. To do the test, dye is injected into a vein in the patient’s arm. The dye travels throughout the body, including the eyes. With a special camera and a flash, photographs will show what kinds of changes have occurred in the retina and the areas which are leaking to help plan the treatment better.

Lasers in Maculopathy

There are two types of laser treatment for non proliferative diabetic retinopathy-local (or specific) treatment, and grid treatment. With local treatment, the specific leaking spots in the retina are found by a fluorescein angiogram, which is then used as a guide for the laser in an attempt to stop the leakage.

In some cases of non proliferative diabetic retinopathy, blood vessels appear to be leaking everywhere in the macula and not just in a few specific areas. In such cases, a scatter of argon laser photocoagulation in a grid pattern is placed across the entire wet macular area.

Laser in PDR

If the amount of new vessels is great, laser treatment can often prevent loss of vision. The type of laser treatment that is done when there are a lot of vessels is called pan-retinal photocoagulation.

This type of laser treatment is usually done in three or more separate sessions. The idea is to use the laser to destroy all of the dead areas of retina where the blood vessels have been closed. When these areas are treated with the laser, the retina stops manufacturing new blood vessels, and those that are already present tend to diminish or disappear.

Injections for Diabetic Retinopathy

Injection  Treatment

Various new injections are given in the eye to reduce the leakage the selling and helps in regressing the new vessels. These injection s include kenort , macugen, avastin etc.
These are given in the operation thertere by instilling drops to num your eyes. It is a painsless procedure lasting 5 mts only some of these drugs might actually improve vision in early cases.

Various injections are given inside the vitrious cavity of the eye to prevent the formation of VEGF and inflammation inducing factors

These injectons are of two types

  • Kenacort Injection- This is a steroid injection which reduced the macular edema and also improves vision in some cases.
  • Anti VEGF injection –eg. Avastin, Macugen, Lucentis. These drugs are selective against VEGF and prevent formation of new vessels and also simultaneously reduce the swelling at macula

Today, not only is the treatment for diabetes so successful, retinopathy can also be successfully treated using lasers. A cure however depends on catching the ailment early.And that is the crux of the problem.

Laser Surgery

Laser treatment, once again, is done in the office as an outpatient procedure. Before treatment, pupils are dilated and drops are applied to numb the eye. It takes 10 to 15 Mts to do laser treatment of both the eye and it cause very mild pain and discomfort.

During the treatment, you may see flashes of light, After the treatment, you might need someone to drive. You back; for the rest of the day, your vision will be a little blurry. Laser treatment is done to treat both diabetic macular edema and proliferative diabetic retinopathy. Timely laser surgery can reduce vision loss from macular edema by half, But you might require laser surgery more than once to control the leaking fluid. Laser light helps in sealing leaking vessels to stabilize the vision and prevent further visual loss.
Similarly, Laser surgery is used to destroy new and abnormal blood vessels that from at the back of the eye. In such cases, rather than to focus the laser light on a single spot, hundreds of small laser spots are placed on the retina. This is called scatter Laser treatment to save the rest of your sight. Laser surgery may also slightly reduce your colour and night vision.
Tips: Remember laser treatment for macular edema does not improve the vision; it only stabilizes it.


Vitrous Surgery for vitreous haemorrhage and RD

Instead of laser Surgery, some patients may require an eye operation called a Vitrectomy to restore mobile vision. This procedure is preformed to remove blood from inside the eye.
Early surgery is recommended in type I diabetics – insulin dependant diabetes melltius– IIDDM as these patients have a greater risk of blindness from complications of proliferative diabetic retinopathy. Vitrectomy is done under local anaesthesia: this means you will be awake during the operation. Your surgeon will make a tiny hole in the sclera, or white of the eye. Next, small sized instruments (about 1mm in diameter) are placed into the eye in order to achieve surgical goals.

Tips: Remember if proliferative diabetic retinopathy remains untreated, about half of those who have it become blind within five years, compared to just five percent of those who receive treatment. In some cases gas or silicon oils is left in the eye as a vitreous substitute.



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