How can diabetes affect eye?
Diabetes can affect the eyes and vision in a number of ways. It may lead to frequent fluctuations in vision, cataract in young age, decreased vision due to involvement of optic nerve, temporary paralysis of the muscles controlling the movement of eyes and thus double vision. The most significant complication of diabetes in eye is diabetic retinopathy and its complications.

What is diabetic retinopathy?
Retina is the inner most layer of the eye that is sensitive to light. Diabetes affects the small vessels of the retina in the eye. There are various stages of diabetic retinopathy:

Non-proliferative or background diabetic retinopathy : When blood vessels in the retina are damaged, they can leak fluid or bleed. This causes the retina to swell and form deposits called exudates. This is an early form of diabetic retinopathy and may not lead to any decrease in vision, but it can lead to other more serious forms of retinopathy that affect the vision.

Macular edema : The fluid and exudates collects in the macula (the part of the retina that allows us to see fine details), thus decreasing the vision. Sometimes there may be a macular edema without any loss of vision. Therefore it is important to have periodic checkup to detect and treat these conditions at an early stage.

Proliferative diabetic retinopathy: This is an advanced stage of diabetic retinopathy, where the blood supply of retina is compromised. In response to this, new fragile blood vessels grow on the surface of the retina (neovascularization). These new vessels are very fragile and bleed easily. These may lead to serious vision problems if they bleed into the vitreous (the clear, jelly-like substance that fills the center of the eye) which is known as vitreous hemorrhage. This prevents the light from reaching the retina and thus can blur the vision.

The new blood vessels and the bleed into the vitreous can also cause scar tissue to develop, which can pull the retina away from the back of the eye. This is known as retinal detachment, and can lead to blindness if untreated.

In addition, abnormal blood vessels can grow on the iris (the colored part in the front of your eye, which can lead to glaucoma).

What are the risk factors for diabetic retinopathy?
The longer the person has diabetes, the greater are his/her chances to develop diabetic retinopathy. Almost 80% of people, who have diabetes for 15 years or more, have some damage to the blood vessels in their retina. The other risk factors are high blood pressure, anemia, kidney diseases, and pregnancy.

Can something be done to prevent diabetic retinopathy?
There is no treatment that can prevent diabetic retinopathy altogether. Persons with any form of diabetes may develop diabetic retinopathy. But it has been proven that a good control of diabetes can delay and slow down the rate of progress of diabetic retinopathy and its complications. Besides a good control of blood sugar, one must exercise regularly, keep the blood pressure under control, avoid smoking, and avoid obesity.

How do I know if I have diabetic retinopathy?
You might not know that you are having diabetic retinopathy, as there are no symptoms in the earlier stages of the disease. Therefore it is essential to have periodic evaluation of your eye by an ophthalmologist to detect the condition early. Early diagnosis and timely treatment is very essential in preventing the complications of this disease and thus maintaining vision.

How frequently should I get my eye examined?
If you have diabetes, you should get a yearly examination with your ophthalmologist. Your pupils may be dilated with eyedrops, so that your ophthalmologist may have a good look at the back of your eye. Once you develop diabetic retinopathy, then your ophthalmologist will advise you if you need some investigations, treatment or just need to follow up. In these cases the frequency of follow up visits is decided on basis of the severity of the disease.

What are the tests done for diabetic retinopathy?
Your vision is assessed by the usual charts. The back of your eye is examined after dilating your pupils, using an instrument called ophthalmoscope. Sometimes your ophthalmologist may advise a special test called Fluorescein angiography.

What is fluorescein angiography?
It is test in which a series of photographs of the retina are taken with the help of a special camera. These photographs are taken after giving the patient an injection of a yellow dye. This dye reaches the retina through the blood stream and helps in seeing the blood vessels of retina more clearly. This test helps the doctor to determine which areas to be treated with laser.

What is the treatment for diabetic retinopathy?
The treatment of diabetic retinopathy is decided on the basis of the stage of the disease. In the very initial stages, it just requires periodic follow up to look for progression of disease. The ophthalmologist decides when to see a patient next depending upon the severity of changes in the retina.

Later when the disease is more advanced he/she may decide to treat it with one or more of the following options:

Laser Treatment : There are well-defined criteria for laser therapy. Laser therapy is done when there is significant maculopathy, or when there are significant new blood vessels in the retina or iris.

Anti-VEGF agents (Lucentis, Avastin, Macugen) : These agents are being used in some selective cases alone or in addition to laser treatment or surgery.

Surgery : Vitrectomy surgery and other additional procedures may be required to manage the complications of diabetic retinopathy, like vitreous hemorrhage, retinal detachment, severe macular edema, etc.



What is Laser treatment?
Most sight threatening complications of diabetic retinopathy can be prevented by laser treatment if given early enough. It involves focusing and applying laser spots on the retina. There are two types of laser treatments depending upon the type of retinopathy:

Diabetic maculopathy: This is treated be applying laser spots in the region of macula to seal the leaking blood vessels.

Proliferative diabetic retinopathy: This condition requires more extensive application of laser in a wider area of retina. It helps the abnormal new vessels to shrink and disappear. It may require more than one sitting to complete the treatment.

It is important to remember that the laser treatment is done to prevent further loss of vision and not to improve the vision. It is highly effective and can prevent blindness in about 80% of the patients.

After the laser treatment, regular follow-ups are required to assess the effect of treatment and to monitor the progress of the disease.

How is the laser performed?
Laser treatment is performed as an outpatient procedure, that is you don't have to be admitted for it. The pupil of the eye is dilated using eye drops. The eye is then numbed with drops (topical anesthetics) so that you don't feel the pain. The patient is seated on a machine and a small contact lens is placed on the cornea. Following this laser treatment is given by this very precise machine. During the treatment, you may be asked to move your eyes in certain directions.

What are the side effects of laser?
The laser treatment may have a few side effects like decrease in the peripheral field of vision, decrease in color vision and difficulty in seeing at night. Sometimes it may also reduce the central vision. This is usually temporary but sometimes this may not improve.

Though no treatment is without any side effects, the risk of the laser treatment are far less than the risk of not having the treatment.

What are Anti VEGF agents, and what is their role in managing diabetic retinopathy?
These agents (Lucentis, Avastin, Macugen) are emerging as the new modality of treatment for various stages of diabetic retinopathy and are showing very promising results. These agents are injected within the eye (intravitreal injection) in a very small painless procedure, inside the OT under aseptic precautions.

What surgery is done for diabetic retinopathy?
In some patients in which the disease is not controlled by the laser, or who have reached the advanced stage of disease, the ophthalmologist may advise a surgery called vitrectomy. The surgeon removes the blood filled vitreous and replaces it with a fluid, using very delicate instruments with the help of a microscope.

Since the blood in the vitreous cavity is replaced by a clear fluid, the light can reach the retina now. This may help restore vision.

Why are regular eye tests so important?
Most of the complications of diabetic retinopathy that cause vision loss are preventable, provided they are detected early and treated. As you may not realize any problem in your vision initially, it is important that you have periodic checkups with an ophthalmologist.

Would eye checks prevent diabetic retinopathy?
No. The eye checkups do not prevent diabetic retinopathy, but recognize it at an early stage. This helps in preventing the vision threatening complications of diabetic retinopathy.

Can I get back my vision after laser surgery?
No. The aim of laser therapy is to preserve the vision and to prevent further loss of vision. It may not restore your vision once it is decreased.

The power of my glasses keeps changing very frequently. Does it have something to do with diabetes?
Yes. The fluctuations in the blood glucose level in diabetes may lead to changes in the shape of the lens of eye. This changes the refractive power of the eye and manifests as frequently changing prescription of glasses.

What are the warning symptoms to contact my ophthalmologist early, if I have diabetic retinopathy?
The following symptoms would require you to contact your ophthalmologist early, even before your next scheduled appointment:

What precautions should I take if I notice blood (red floaters) in my vision?
Do not bend down or do any strenuous activity. Contact your ophthalmologist at the earliest.

Does pregnancy have any effect on diabetic retinopathy?
Yes. The diabetic retinopathy may worsen during pregnancy. Therefore, if you are a diabetic, contact your ophthalmologist before planning your pregnancy. After doing a check up, he or she may advise you to undergo laser treatment before commencing pregnancy. Moreover, during pregnancy, you must visit your ophthalmologist regularly to detect any worsening of the disease.

If someone loses his/her vision due to diabetic retinopathy, what are the other helps available?
Special devices called low vision aids may help those who have very poor vision. These devices may help them to read and to perform their daily activities. Moreover, the ophthalmologist may issue them a certificate of visual disability that entitles them to certain benefits.

Is there any association of cataract with diabetes?
Yes. Diabetes may sometimes lead to sudden development of cataract in young. Moreover the onset of usual cataract is earlier in diabetics than in non-diabetics.

Is there any association of glaucoma with diabetes?
Yes. Diabetics are a higher risk of having glaucoma.

Is there any association between diabetic retinopathy and other complications of diabetes?
Presence of diabetic retinopathy suggests that other complications of diabetes in the body must also be taking place. These complications affect the kidney, heart, brain, peripheral nerves and blood vessels. Your physician treating you for diabetes would do the necessary checkups and advise you regarding the treatment.