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Eye conditions

Diabetic retinopathy

What is Diabetic Retinopathy?
Diabetic Retinopathy is the damage that is caused to the blood vessels of your retina because of diabetes. Sometimes these vessels swell and leak fluid or even close off completely. You are more likely to develop diabetic retinopathy, the longer you have had diabetes (Type 1 or Type 2) and the more uncontrolled your diabetes is.

What causes Diabetic Retinopathy?
When blood sugar levels are too high for extended periods of time, it can damage capillaries (tiny blood vessels) that supply blood to the retina. 
Maintaining strict control of blood sugar and blood pressure, as well as having regular diabetic retinopathy screenings by your eye doctor, are keys to preventing diabetic retinopathy and vision loss.

 There are two types of Diabetic Retinopathy:
1. Background or Non Proliferative Diabetic Retinopathy:

Nonproliferative diabetic retinopathy (NPDR) is the earliest stage of diabetic retinopathy. With this condition, damaged blood vessels in the retina begin to leak extra fluid and small amounts of blood into the eye. Sometimes, deposits of cholesterol or other fats from the blood may leak into the retina.

NPDR can cause changes in the eye, including:

• Microaneurysms: small bulges in blood vessels of the retina that often leak fluid.

• Retinal hemorrhages: tiny spots of blood that leak into the retina.

• Hard exudates: deposits of cholesterol or other fats from the blood that have leaked into the retina.

• Macular edema: swelling or thickening of the macula caused by fluid leaking from the retina's blood vessels leading to the malfunctioning of the macula. Macular edema is the most common cause of vision loss in diabetes.

• Macular ischemia: small blood vessels (capillaries) close. Your vision blurs because the macula no longer receives enough blood to work properly.

Many people with diabetes have mild NPDR, which usually does not affect their vision. However, if their vision is affected, it is the result of macular edema and macular ischemia. 

2. Proliferative / Advanced Diabetic Retinopathy:

Proliferative diabetic retinopathy (PDR) mainly occurs when many of the blood vessels in the retina close, preventing enough blood flow. In an attempt to supply blood to the area where the original vessels closed, the retina responds by growing new blood vessels. This is called neovascularization. However, these new blood vessels are abnormal and do not supply the retina with proper blood flow. The new vessels are also often accompanied by scar tissue that may cause the retina to wrinkle or detach.

PDR may cause more severe vision loss than NPDR because it can affect both central and peripheral vision. PDR affects vision in the following ways:

Vitreous haemorrhage: These new blood vessels being delicate bleed into your vitreous (the gel in your eye) — preventing light rays from reaching the retina. This vitreous haemorrhage may either cause floaters or might completely block your vision, allowing you to perceive only light and dark. Vitreous haemorrhage alone does not cause permanent vision loss. When the blood clears, your vision may return to its former level unless the macula has been damaged.

Traction retinal detachment: These new blood vessels are often found along with formation of scar tissue which crumples, pulls and detaches your retina. This wrinkling and detachment cause further vision loss. Macular wrinkling can distort your vision. More severe vision loss can occur if the macula or large areas of the retina are detached.

Neovascular glaucoma: Because of new blood vessels forming in your iris (coloured part of your eye) the normal outflow of fluid gets blocked. This causes pressure to increase in the eye which leads to damage to your optic nerve.

Following are the risk factors:
Longer duration of diabetes
Uncontrolled high blood sugars
High cholesterol
High blood pressure
Smoking
Pregnancy

Do I have Diabetic Retinopathy? (Signs and Symptoms)

Often there are no symptoms in the early stages of the disease, nor is there any pain. Don't wait for symptoms. Be sure to have a comprehensive dilated eye exam at least once a year.

Gradually as the damage goes on occurring, you may notice:
Blurring of vision
Fluctuations in Vision
Spots or strings floating in front of your eyes
Difficulty in perceiving colours
Shadows or dark areas in your vision
Distorted vision
Usually both your eyes will get affected.

What are the complications of Diabetic Retinopathy?
Vitreous Hemorrhage
Retinal Detachment
Glaucoma
Blindness

What are the tests for Diabetic Retinopathy?
Diabetic Retinopathy is best diagnosed by an examination of your eyes which is done after dilating your eyes with drops.
Also, the following tests may be done:
Vision Test
Eye pressure testing
Fluorescein Angiography: This helps to see the damage to your blood vessels.
Optical Coherence Tomography: This helps to see the thickness of your retina and know if fluid has leaked into it.

What is the treatment for Diabetic Retinopathy?
It depends on the stage of your disease:
Early:
In the early stages, you may only require regular monitoring by your eye doctor along with strict control of your blood sugars.
Advanced:

Here, surgery is usually required.
• Focal laser treatment / Photocoagulation:
This is used to slow down or stop the leakage of fluid or blood into your eye. If your blurred vision was due to swelling of your macula, your vision might not become completely normal.
• Scatter Laser Treatment / Pan- retinal Photocoagulation:
Laser burns are used to shrink and scar the abnormal blood vessels. This is used for areas that are away from the macula.
• Vitrectomy: This is used to remove blood from the vitreous as well as scar tissues in your eye. The gel that is removed is replaced with a salt solution.
Surgery can be used to slow down the damage or halt its progress; however total cure is not possible. Hence, regular visits to your eye doctor for examinations cannot be substituted.

How can I prevent Diabetic Retinopathy?
• Keep a strict check over your diabetes. Regular exercises and blood sugar monitoring are a must.
• Get an HbA1C test done. This helps you know the average blood sugar levels over the last 3 months.
• Keep your blood pressure and cholesterol under control.
• Quit smoking
• Keep an eye on your vision so that you will be able to notice the slightest change.
• Visit your eye doctor regularly even if you do not experience any symptoms.