AND THE EYES
Diabetes can cause cataracts and diabetic
retinopathy. Cataracts are usually easy to treat by performing a
simple operation. Diabetic retinopathy,
on the other hand, is a potentially
blinding complication of diabetes that damages the eye's retina.
In the early stages, diabetic retinopathy
does not produce any noticeable change in
your vision. But it could get worse
over the years and threaten your good vision. With timely
treatment, 90 percent of those with advanced diabetic
retinopathy can be saved from going blind. People with diabetes
should have an eye examination through dilated pupils at least
once a year.
What Is the Retina?
The retina is a
light-sensitive carpet-like tissue at the back of the eye. When
light enters the eye, the retina changes the light into nerve
signals. The retina then sends these signals along the optic
nerve to the brain. Without a retina, the eye cannot communicate
with the brain, making vision impossible.
How does Diabetic Retinopathy
Damage the Retina?
occurs when diabetes damages the tiny blood vessels in the
retina. At this point, most people do not notice any changes in
their vision. Some people develop a condition called macular
edema. It occurs when the damaged blood vessels leak fluid and
lipids onto the macula, the part of the retina that lets us see
detail. The fluid makes the macula swell, blurring vision. As
the disease progresses, it enters its advanced, or
proliferative, stage. Fragile, new blood vessels grow along the
retina and in the clear, gel-like vitreous that fills the inside
of the eye. Without timely treatment, these new blood vessels
can bleed, cloud vision, and destroy the retina.
Who Is at Risk for this Disease?
All people with diabetes
are at risk—both those with Type I
diabetes and those with Type II
diabetes (adult onset). During pregnancy, diabetic retinopathy
may also be a problem for women with diabetes. It is recommended
that all pregnant women with diabetes have dilated eye
examinations each trimester to protect their vision.
What Are Its Symptoms?
often has no early warning signs. At some point, though,
you may have macular edema. It blurs vision, making it hard to
do things like read and drive. In some cases, your vision will
get better or worse during the day. As new blood vessels form at
the back of the eye, they can bleed (hemorrhage) and blur
vision. The first time this happens it may not be very severe.
In most cases, it will leave just a few specks of blood, or
spots, floating in your vision. They often go away after a few
hours. These spots are often followed within a few days or
weeks by a much greater leakage of blood. The blood will blur
your vision. In extreme cases, a person will only be able to
tell light from dark in that eye. It may take the blood anywhere
from a few days to months or even years to clear from inside of
your eye. In some cases, the blood will not clear. You should be
aware that large hemorrhages tend to happen more than once,
often during sleep.
How Is It Detected?
Diabetic retinopathy is
detected during an eye examination that includes:
Visual acuity test:
This eye chart test measures how well you see at various
The eye care professional places drops into the eye to widen the
pupil. This allows him or her to see more of the retina and look
for signs of diabetic retinopathy. After the examination,
close-up vision may remain blurred for several hours.
This is an examination of the retina in which the eye care
professional: (1) looks through a device with a special
magnifying lens that provides a narrow view of the retina, or
(2) wearing a headset with a bright light, looks through a
special magnifying glass and gains a wide view of the retina.
A standard test that determines the fluid
pressure inside the eye. Elevated pressure is a possible sign of
glaucoma, another common eye problem in people with diabetes.
Your eye care
specialist will look at your retina for early
signs of the disease, such as: (1) leaking blood vessels, (2)
retinal swelling, such as macular edema, (3) pale, fatty
deposits on the retina—signs of leaking blood vessels, (4)
damaged nerve tissue, and (5) any changes in the blood vessels.
Should your doctor
suspect that you need treatment for macular edema, he or she may
ask you to have a test called fluorescein angiography. In this
test, a special dye is injected into your arm. Pictures are then
taken as the dye passes through the blood vessels in the retina.
This test allows your doctor to find the leaking blood vessels.
How Is It Treated?
There are two treatments
for diabetic retinopathy. They are very effective in reducing
vision loss from this disease. In fact, even people with
advanced retinopathy have a 90 percent chance of keeping their
vision when they get treatment before the retina is severely
damaged. These treatments are:
Doctors will perform laser surgery to treat severe macular edema
and proliferative retinopathy.
Timely laser surgery can reduce vision loss from macular edema
by half. But you may need to have laser surgery more than once
to control the leaking fluid.
During the surgery, your
doctor will aim a high-energy beam of light directly onto the
damaged blood vessels. This is called focal laser treatment.
This seals the vessels and stops them from leaking. Generally,
laser surgery is used to stabilize vision, not necessarily to
Retinopathy: In treating advanced
diabetic retinopathy, doctors use the laser to destroy the
abnormal blood vessels that form at the back of the eye.
Rather than focus the
light on a single spot, your eye care professional will make
hundreds of small laser burns away from the center of the
retina. This is called scatter laser treatment. The treatment
shrinks the abnormal blood vessels. You may
lose some of your side vision after this surgery to save the
rest of your sight. Laser surgery may also slightly reduce your
color and night vision.
Laser surgery is
performed in a doctor's office or eye clinic. Before the
surgery, your ophthalmologist will: (1) dilate your pupil and
(2) apply drops to numb the eye. In some cases, the doctor also
may numb the area behind the eye to prevent any discomfort. The
lights in the office will be dimmed.
As you sit facing the laser machine, your doctor will hold a
special lens to your eye. During the procedure, you may see
flashes of bright green or red light. These flashes may
eventually create a stinging sensation that makes you feel a
You may leave the office
once the treatment is done, but you will need someone to drive
you home. Because your pupils will remain dilated for a few
hours, you also should bring a pair of sunglasses. For the rest
of the day, your vision will probably be a little blurry. Your
eye may also hurt a bit. This is easily controlled with drugs
that your eye care professional suggests.
If you have a lot of blood in the vitreous, you may need an eye
operation called a vitrectomy to restore sight. It involves
removing the cloudy vitreous and replacing it with a salt
solution. Because the vitreous is mostly water, you will notice
no change between the salt solution and the normal vitreous.
Studies show that people
who have a vitrectomy soon after a large hemorrhage are more
likely to protect their vision than someone who waits to
have the operation. Early vitrectomy is especially effective in
people with insulin-dependent diabetes, who may be at greater
risk of blindness from a hemorrhage into the eye. Vitrectomy is
often done under local anesthesia (using drops to numb the eye).
This means that you will be awake during the operation. The
doctor makes a tiny incision in the sclera, or white of the eye.
Next, a small instrument is placed into the eye. It removes the
vitreous and inserts the salt solution into the eye.
You may be able to
return home soon after the vitrectomy. Or, you may be asked to
stay in the hospital overnight. Your eye will be red and
sensitive. After the operation, you will need to wear an
eyepatch for a few days or weeks to protect the eye. You will
also need to use medicated eye drops to protect against
infection. Although laser surgery and vitrectomy are very
successful, they do not cure diabetic retinopathy. Once you have
proliferative retinopathy, you will always be at risk for new
bleeding. This means you may need treatment more than once to
protect your sight.
What Research Is Being Done?
Many research studies in
both the laboratory and with patients to learn more about the
cause of diabetic retinopathy are being done. This research
should provide better ways to detect, treat, and prevent vision
loss in people with diabetes. For example, it is likely that in
the coming years researchers will develop drugs that turn off
enzyme activity that has been shown to cause diabetic
retinopathy. Some day, these drugs will help people to control
the disease and reduce the need for laser surgery.
What Can You Do To Protect Your Vision?
All people with diabetes
should have an eye examination through
dilated pupils at least once a year. If you have more serious
retinopathy, you may need to have a dilated eye examination more
often. A recent study, the Diabetes Control and Complications
Trial (DCCT), showed that better control of blood sugar level
slows the onset and progression of retinopathy and lessens the
need for laser surgery for severe retinopathy. The study found
that the group that tried to keep their blood sugar levels as
close to normal as possible, had much less eye, kidney, and