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Diabetes and the Eye

Are you worried about diabetes affecting your eyes and vision. Well today we will be talking more about the effect diabetic patients may experience with their eyes. So the first question to answer is “What is Diabetes?”

In diabetes, there is too much sugar in the blood.

When the blood sugar is constantly or frequently high, many complications occur: eyesight can suffer, heart attacks and other blood vessel problems can occur, and one’s lifespan can be shortened. When the blood sugar is maintained at a normal level, the complications of diabetes including serious diabetic retinopathy can be reduced. Controlling blood sugar is the single most important thing a person with diabetes can do to prevent the complications of diabetes.

Type 1 diabetes usually occurs at a young age. People with Type 1 diabetes must take insulin to survive and to control blood sugar. They should test their own blood sugar levels with a glucometer several times a day so they can adjust their diet, exercise, and insulin doses to keep the blood sugar at the required level. They should follow a diet controlled in carbohydrates and low in fat and cholesterol. Regular exercise is also important as it helps reduce blood sugar.

Type 2 diabetes usually starts in adult life and is often not dependant on insulin for control of blood sugar. Maintaining normal weight and a diet low in calories, fat and cholesterol is very important. Blood sugar can be controlled either with diet alone or in combination with pills to lower blood sugar. In some cases, insulin treatment is also necessary.

In addition to the importance of diet and exercise, there are other factors that can affect diabetes. High blood pressure is very bad for people with diabetes because it increases the risk of complications, including vision loss. Smoking is known to be particularly bad for people with diabetes because it promotes the closure of blood vessels.

What is Diabetic Retinopathy?

Diabetic Retinopathy is the most common eye disease associated with diabetes. In diabetic retinopathy, the blood vessels of the retina become abnormal and this causes the problems that people with diabetes have with their eyesight. Normally, the blood vessels of the retina do not leak. But with diabetes, the retinal blood vessels can develop tiny leaks. These leaks cause blood to seep into the retina. The retina then becomes wet and swollen and cannot work properly. The form of diabetic retinopathy caused by leaking retinal blood vessels is called Nonproliferative Diabetic Retinopathy (NPDR).

Another problem with the retinal blood vessels in diabetes is that they can close. The retinal tissue which depends on those vessels for nutrition, will no longer work properly. This causes the growth of new abnormal blood vessels, which can be very bad for the eye. These new blood vessels are weak and can cause bleeding and scar tissue which can cause blindness (total loss of vision). This type of retinopathy which causes closure of blood vessels and the growth of new vessels is called Proliferative Diabetic Retinopathy (PDR).

Nonproliferative Diabetic Retinopathy (NPDR)

In diabetes, the retinal blood vessels can develop tiny leaks. Blood and fluid seep from the retinal blood vessels and fatty material deposits in the retina. This causes swelling of the retina, and it is called nonproliferative diabetic retinopathy (NPDR).

When this occurs in the central part of the retina (macula), vision will be reduced or blurred. Leakage elsewhere in the retina will have no effect on vision.

A patient with a wet, swollen macula, or with exudates in the macula, will have some loss of vision, including blurring, distortion, or darkening. If one eye is affected, the other eye may also be affected, though the problem may not be equally severe in both eyes. If diabetic retinopathy has affected each macula severely, central vision may be lost from each eye and the ability to see detail will be lost. These patients learn to use the areas outside the macula to see some detail. This ability to look slightly off centre usually improves with time, though the eyesight will never be as good as it was before the central retina (macula) was damaged by leaky blood vessels. So people who have NPDR will usually be able to see well enough to take care of themselves and continue those activities that do not require detailed vision.

Proliferative Diabetic Retinopathy (PDR)

In PDR, retinal blood vessels close off and large areas of the retina lose their source of nutrition. When this happens, peripheral or side vision is reduced, and the person’s ability to see at night and adjust from light to dark is often diminished.

As a result of this loss of nourishing blood flow, the retina responds by developing new blood vessels that are abnormal. This can be a huge problem and can be very dangerous to the eye. These new vessels do not nourish the retina properly and may start to bleed and cause scar tissue on the retina. The scar tissue pulls the retina off the back of the eye and causes a detachment. This can lead to severe vision loss or even total blindness.

Sometimes these new blood vessels can also grow on the iris (coloured part of the eye), and it may close off the normal flow of fluid out of the eye. This results in increased pressure in the eye and causes glaucoma. This causes permanent changes, resulting in vision loss, pain, and even total loss of the eye.

It may be impossible for a person with diabetes and early PDR to know that any of these changes are occurring. For this reason, it is essential that every person with diabetes be examined regularly by an ophthalmologist or optometrist. These examinations should occur regularly, every 6-12 months, depending on the degree of retinopathy. The earlier theses changes are discovered, the better the chance of saving vision. The later these changes are discovered, the greater the chance of blindness.

Treatment of Diabetic Retinopathy

Laser Surgery

Laser surgery can be very helpful in the treatment of diabetic retinopathy. The laser beam is a high energy light that turns to heat when it is focused on the parts of the retina to be treated. In NPDR, the laser seals the leaking blood vessels or reduces the leakage and allows the retina to dry. In PDR, the laser destroys the diseased portions of the retina to stop the growth of the abnormal new blood vessels.

Essentially, the major purpose of laser surgery is to prevent further vision loss. Laser surgery may not always be best or even possible. The decision to use laser depends mostly on the type of diabetic retinopathy, its severity, and a judgment regarding how well it may respond to laser surgery.

Because diabetes is a condition for which there is currently no cure, the diabetes may continue to damage the retina. Even with laser surgery patients may continue to lose vision. But when laser is the right treatment, the chances are that it can prevent further visual loss.

Questions about Laser Surgery

What is the purpose of laser surgery?

In NPDR, the leaking blood vessels cause the retina to become wet and swollen, causing vision loss. Laser surgery stops the leakage from these vessels to prevent vision loss.

In PDR, the growth of new abnormal blood vessels causes severe visual loss by bleeding into the eye and forming scar tissue which pulls on the retina causing a retinal detachment. The laser stops this growth and detachment and thus prevents further visual loss.

Will I have to go to hospital?

Laser surgery is usually done in the doctor’s office or in the hospital as outpatient surgery. After the surgery, you will be able to go home and resume your normal activities without special restrictions.

Is the surgery safe?

In most cases, no complications occur but, as with all surgery, there are some risks. There is a small chance that the laser beam might not be aimed properly and that healthy retina might be destroyed and vision lost. Laser might also cause bleeding and scarring. Fortunately, these complications are rare.

What are the after effects of laser surgery?

Certain types of laser surgery may cause loss of night vision. So these patients might not be able to drive at night. Sometimes peripheral or side vision may be reduced after surgery. Most patients have some degree of blurring of central vision which passes with time but in a few patients it may be permanent. Rarely, there is a lot of swelling after surgery which causes an increase in eye pressure. This is very painful and the patient should call the treating ophthalmologist immediately.

Are the effects of the laser permanent?

In most cases, leaking blood vessels remain closed and the growth of new abnormal blood vessels is stopped permanently after surgery. But because diabetes continues, it is common for the leakage to develop in new areas. If laser surgery is indicated, however, the outcome is always better than if no surgery is done.

Does laser surgery cause any pain?

For NPDR, laser surgery is almost always painless, though a few patients do experience some discomfort. After the laser surgery, the eye is patched for the rest of the day. In PDR, many patients experience some pain. The eye is usually anesthetized.

How long does laser surgery take?

Depending on the extent of the problem, laser surgery for NPDR may take anywhere from a few minutes to a half hour. For PDR it may take from 15 minutes to an hour or more.

What will my vision be like after laser?

Vision is often blurred but it usually improves within a month. There will be small black areas or blind spots where the laser spots were placed. These will be permanent but become less noticeable with time. Peripheral and night vision is likely to be reduced.

How many treatments will I need?

For NPDR, usually one treatment is all that is required. However, if new leaks develop later, additional surgery will be necessary. For PDR, two or three sessions are usually required.

Can anything help if central vision is lost in each eye?

Those patients who have lost central vision in both eyes will be referred to a low vision specialist who helps patients learn to use their remaining vision to its fullest. They make use of low vision aids like magnifying lenses, telescopic lenses, special filters etc.

Will using my eyes hurt them?

You cannot hurt your eyes by using them. There is no way in which using your eyes can do your eyes any harm, whether by reading, watching television or driving.

Diabetes and Your Eyes

If there is a fairly large, rapid shift in your blood glucose level, you may notice that your vision becomes blurry. This may occur prior to the diagnosis of diabetes, or it may develop after the initiation of treatment or a change in treatment of diabetes. This difficulty with vision or focusing will disappear once the blood sugar has been stabilized for about 1 week. So, measure your own vision in each eye, separately, each day. Know what you can see each day. If you notice a change in your vision, call your optometrist or ophthalmologist for an appointment. It is important for all patients with diabetes to have a thorough retinal exam regularly, about every 6-12 months, even when there are no problems. Also, be sure to talk to your own medical doctor about the importance of diet and exercise and the dangers of smoking and high blood pressure. And, most of all learn to maintain the best possible control of blood sugar.

Pineslopes Optometrists will always be available to answer your questions and to help in every way possible. You are encouraged to call with any unusual symptom or worry. We are here to help you.

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