Diabetes and the Eye
What is Diabetes?
When you have diabetes, your body can't properly control the levels of
sugar (glucose) in your blood. If your body doesn't produce enough of a
hormone called insulin you have type 1 diabetes. If your body's tissues
don't respond properly to the action of insulin (insulin resistance) you
have type 2 diabetes.
Over 1.5 million Canadians are believed to have diabetes, and about half
of those don't know they have it. Diabetes can affect many parts of your
body, including your blood vessels, nerves, kidneys, heart, and eyes. It
blinds 400 Canadians every year.
How Does Diabetes Affect The Eyes?
If your blood glucose levels are too high or they are not well
controlled, you may have blurred vision and your eyeglass prescription
may change. It may also be hard for your eyes to focus properly.
Controlling your blood glucose levels usually fixes this. As well,
diabetes can lead to other eye problems, such as cataracts, double
vision, or glaucoma.
An important cause of vision problems in people with diabetes is
diabetic retinopathy. This is a change in the tiny blood vessels that
feed the retina. In the early stages, the blood vessels weaken and leak
fluid or tiny amounts of blood. This causes swelling of the retina. This
is called "nonproliferative" or "background" retinopathy. At this stage
you may have normal vision or you may notice that your vision has
blurred or changed. About 1 in 4 people with diabetes have some
nonproliferative retinopathy.
When retinopathy is more advanced, the blood vessels become blocked or
closed and parts of the retina die. New, abnormal blood vessels grow to
replace the old ones. This is called "proliferative" retinopathy, and it
affects about 1 in 20 people with diabetes. The new vessels are fragile
and often bleed into the eye, blocking your vision. Then scar tissue
forms, and it shrinks and tears the retina and makes it bleed or even
detach from the back of your eye. This can lead to severe visual loss or
blindness. Fortunately, this happens in only a small percentage of
people with diabetes.
The longer you have diabetes, the higher your risk of having diabetic
retinopathy. Most people who have had diabetes for more than 20 years
have some form of retinopathy.
How Is Diabetic Retinopathy Diagnosed?
If diabetic retinopathy is diagnosed early enough, your doctor may be
able to prevent or delay severe vision loss. People with diabetes should
have an annual eye exam by an ophthalmologist. The ophthalmologist may
take a special photograph of your retina called a "fluorescein
angiogram."
How Is Diabetic Retinopathy Treated?
Laser treatment seals leaky blood vessels and stops the growth of new
ones. There are advantages and few disadvantages to laser treatment.
Your ophthalmologist will discuss the benefits and risks of laser
treatment with you. In cases of more advanced retinopathy, the benefits
usually outweigh the risks.
If retinopathy is not treated (or sometimes even if it is treated), some
people bleed heavily into their eye. To treat this, the ophthalmologist
has to do a delicate operation called a vitrectomy to remove the blood
and scar tissue. You may also need surgery if your retina detaches from
the back of your eye.
Can Diabetic Retinopathy Be Prevented?
Research has shown that controlling blood glucose and blood pressure
levels can delay the development of retinopathy or slow its progression
in some people. People with diabetes should work closely with their
health care team to control their diabetes.
Research into diabetes and diabetic retinopathy is continuing, so we can
hope for prevention and better treatment in the future.
© Copyright by the Canadian Ophthalmological Society