| Diabetic Retinopathy |
Diabetes
affects 16 million Americans and is the leading cause of new cases of
blindness in people ages 20 to74. Each year from 12,000-24,000 people
will lose their sight from the disease. Vigilant care, in particular
controlling the blood sugar, blood pressure and cholesterol, can
markedly reduce the risk of vision complications for diabetics, and for
those that do develop problems, various treatments offer hope for
saving or recovering some sight.
What is diabetes?
Diabetes is a chronic disease in which the body does not
produce or properly use insulin, a hormone that helps convert sugar and
food into energy. The biochemical reactions that occur because the body
doesn’t have the proper mean of regulating blood sugar can have a
profound impact on the eyes. A high sugar level thickens the lens and
bends the light that filters through. When sugar levels decrease, just
the opposite happens. The constant thickening and thinning of the lens
due to dramatic swings in blood sugar levels leads to blurry vision and
increases the risk of cataract formation. For people who are unaware
that they have diabetes, blurry vision is often the first sign that
something is amiss. For those who know they are diabetic, blurry vision
is a warning to get blood sugar levels under control through a
combination of diet, exercise and medication.
What is diabetic retinopathy?
The chemical changes caused by diabetes can damage blood
vessels throughout the body, including the fine blood vessels in the
retina. This damage is called diabetic retinopathy, of which there are
two kinds:
Nonproliferative diabetic retinopathy (NPDR) occurs when the
retinal blood vessels start to leak, causing blood or fluid to seep
into the retina. The retina becomes thick and swollen and does not work
correctly. If the leaking happens in the macula, (the central part of
the retina), vision will be blurred from macular edema. If the leaks
occur on the periphery of the retina, there may be no immediate impact
on vision.
Proliferative diabetic retinopathy (PDR) occurs when the
retinal blood vessels close, cutting off nutrition to the retinal
tissue. Abnormal new blood vessels, called neovascularization, may form
and cause bleeding and scar tissue. The bleeding (called vitreous
hemorrhage because the blood fills up the vitreous cavity inside the
eye) and scar tissue can result in blindness if not treated. The
earlier neovascularization is discovered, the better the chance that
surgery can save vision.
Both types of diabetic retinopathy may occur without a
noticeable change in vision. It is therefore imperative, if you have
diabetes, to have your retinas examined at least once every 12 months,
and more often than that if you have already developed significant
retinopathy.
How is diabetic retinopathy treated?
For patients with NPDR and diabetic macular edema, laser
surgery can seal the blood vessels to stop leaking and prevent further
vision loss. Typically a fluorescein angiogram is performed to pinpoint
the exact locations of the leaks. Ocular coherence tomography (OCT) is
also often performed to evaluate the extent of macular edema. Even
after laser surgery is done, new leaks may develop or sealed leaks may
reopen, requiring additional laser treatments. That is why it is very
important to check your vision one eye at a time routinely and report
any changes or blurriness to your doctor.
Severe neovascularization resulting from PDR can also be treated with
in-office laser surgery to prevent severe vision loss. For patients who
don’t respond to the laser, and develop recurrent bleeding or
tractional membranes, a vitrectomy may be indicated. A vitrectomy
removes the jelly-like substance in the center of the eye, called the
vitreous. This is where the abnormal diabetic blood vessels and
hemorrhaging are located, so the vessels and blood are removed with the
vitreous. Any scar tissue that has formed is also removed.
Intravitreal Kenalog injections (IVK) can also be employed in the treatment of intractable diabetic macular edema. |
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