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If you have diabetes mellitus, your body does not use and
store sugar properly. Diabetes can cause high blood-sugar levels,
excessive thirst and urination. It can also cause changes in the
body's blood vessels, the veins and arteries that carry blood
throughout your body.
Because diabetes affects your body in these ways, it can
affect vision by causing cataracts, glaucoma and, most
importantly, damage to blood vessels inside the eye.
What is diabetic retinopathy?
Diabetic retinopathy is a complication of diabetes that is
caused by changes in the blood vessels of the eye. The retina is
a nerve layer at the back of the eye that senses light and helps
to send images to your brain (click image to enlarge).
When blood vessels in the retina are damaged, they may leak
fluid or blood, and grow fragile, brush-like branches and scar
tissue. This can blur or distort the images that the retina sends
to the brain.
Diabetic retinopathy is the leading cause of new blindness
among adults in the United States. People with untreated diabetes
are said to be 25 times more at risk for blindness than the
general population.
Diabetes damages blood vessels in the retina, and can cause
them to leak or grow abnormally.
The longer a person has diabetes, the more the risk of
developing diabetic retinopathy increases. About 80% of the
people who have had diabetes for at least 15 years have some
blood vessel damage to their retina. People with Type 1, or
juvenile, diabetes are more likely to develop diabetic
retinopathy at a younger age.
If you have diabetes, it's important to know that today,
with improved methods of diagnosis and treatment, only a small
percentage of people who develop retinopathy have serious vision
problems.
Types of diabetic retinopathy
Background retinopathy is an early stage of diabetic
retinopathy.
In this stage, tiny blood vessels within the retina become
damaged and leak blood or fluid. Leaking fluid causes the retina
to swell or to form deposits called exudates.
While this stage usually doesn't affect your vision, it
can lead to more sight-threatening stages. For this reason,
background retinopathy is considered a warning sign.
Sometimes the leaking fluid collects in the macula, the part
of the retina that lets us see fine details, like letters or
numbers. This problem is called macular edema. Reading and close
work may become more difficult because of this condition.
Proliferative retinopathy describes the changes that
occur when new, abnormal blood vessels begin growing on the
surface of the retina.
The abnormal growth is called neovascularization. These new
blood vessels have weaker walls and may break and bleed. The
vitreous is the clear, jelly-like substance that fills the center
of the eye. Leaking blood can cloud the vitreous and partially
block the light passing through the pupil towards the retina,
causing blurred and distorted images.
These abnormal blood vessels may grow scar tissue that can
pull the retina away from the back of the eye. This is called a
retinal detachment. If left untreated, a retinal detachment can
cause severe vision loss.
Abnormal blood vessels may also grow around the pupil (on the
iris) causing glaucoma by increasing pressure within the eye.
Proliferative diabetic retinopathy is the most serious
form of diabetic retinal disease. It affects up to 20% of
diabetics and can cause severe loss of sight, including
blindness.
What are the symptoms of diabetic retinopathy?
There are usually no symptoms of background retinopathy,
although gradual blurring of vision may occur if macular edema is
present. You may never notice changes in your vision.
A medical examination is the only way to find changes inside
your eye.
When bleeding occurs, your sight may become hazy, spotty or
even disappear altogether. While there is no pain, proliferative
retinopathy is a severe form of the disease and requires
immediate medical attention. Pregnancy and high blood pressure
may aggravate diabetic retinopathy.
How is diabetic retinopathy diagnosed?
The best protection against diabetic retinopathy is to have
regular medical eye examinations by your ophthalmologist (medical
eye doctor). Serious retinopathy can be present without any
symptoms. The disease can improve with treatment.
To find diabetic retinopathy, the ophthalmologist looks at the
inside of the eye using an instrument called an ophthalmoscope.
The pupils may need to be dilated (enlarged) with eye drops.
If your ophthalmologist finds diabetic retinopathy, he or she
may order color photographs of the retina or a special test
called fluorescein angiography to find out if you need treatment.
Fluorescein angiography is a test where dye is injected in your
arm and special photos of your eye are taken.
How is diabetic retinopathy treated?
Your ophthalmologist will consider:
- Your age
- Your medical history
- Your lifestyle
- How much your retina is damaged
In many cases treatment is not necessary, but you will need to
continue having regular eye exams. In other cases, treatment is
recommended to stop the damage of diabetic retinopathy and
improve sight whenever possible.
Laser surgery: This procedure is often helpful in
treating diabetic retinopathy. A powerful beam of laser light is
focused on the damaged retina. Small bursts of the laser's
beam seal leaking retinal vessels to reduce macular edema. This
is called photocoagulation (click image to enlarge).
For abnormal blood vessel growth (neovascularization), the
laser beam bursts are scattered throughout the side areas of the
retina. The small laser scars reduce the abnormal blood vessel
growth and help bond the retina to the back of the eye,
preventing retinal detachment. click on photo to enlarge
In photocoagulation, a laser is focused on the retina to seal
leaking blood vessels and reduce abnormal blood vessel
growth.
Laser surgery may be performed in your ophthalmologist's
office or an out- patient clinic. If diabetic retinopathy is
detected early, laser surgery slows down vision loss. Even in the
more advanced stages of the disease (proliferative retinopathy),
it reduces the chance of severe visual impairment.
Cryotherapy: If the vitreous is clouded by blood, laser
surgery cannot be used until the blood settles or clears. In some
cases of bleeding into the vitreous, cryotherapy, or freezing, of
the retina may help shrink the abnormal blood vessels.
Vitrectomy: In advanced proliferative diabetic
retinopathy, the ophthalmologist may recommend a vitrectomy. This
microsurgical procedure is performed in the operating room.
Vitrectomy removes the blood-filled vitreous and replaces it with
a clear solution.
About 70% of vitrectomy patients notice an improvement in
sight after surgery. Sometimes the ophthalmologist may wait from
several months up to a year to see if the blood clears on its
own, before going ahead with a vitrectomy.
Retinal repair: If scar tissue detaches the retina from
the back of the eye, severe sight loss or blindness can result
unless surgery is performed to reattach the retina.
What is your part in treatment?
Successful care of diabetic retinopathy depends on more than
early treatment by your ophthalmologist. Your attitude and
attention to medications and diet are essential. You must
maintain blood sugar levels, avoid smoking and watch your blood
pressure.
Physical activity is usually no problem for people with
background retinopathy. Occasionally, people with active
proliferative retinopathy are advised to restrict physical
activity.
Vision loss is largely preventable
Diabetic retinopathy may be present without any symptoms.
Early detection of diabetic retinopathy is the best protection
against loss of vision. People with diabetes should schedule
examinations by an ophthalmologist at least once a year. More
frequent medical eye examinations maybe necessary once diabetic
retinopathy has been diagnosed.
With careful monitoring, the ophthalmologist can begin
treatment before sight is affected. Laser and operative surgery
are highly effective treatment for diabetic retinopathy.
If you have questions or would like further information,
contact your ophthalmologist.
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