How Diabetes Can Adversely Affect Your
Eyes
November 1-30 is Diabetic Eye Disease Awareness
Month. Many are unaware that diabetes can lead to vision loss
when untreated. Ophthalmologists at the Emory Eye Center routinely treat
patients who have the particular complications of diabetes
that affect their vision.
Diabetic retinopathy is a complication of diabetes,
which can weaken the retina and block, distort or blur vision. While
no one knows why diabetes sometimes causes abnormal blood vessels to
form in the back of the eye, current research is providing some answers.
With diabetic retinopathy these new vessels can leak fluid into the
retina or vitreous humor (the jelly that fills the eye) and contract,
distort or detach the retina.
Retinopathy is strongly linked to duration, so that people who have
had diabetes for 15 years or more are at strong risk of developing this
sight-stealing disease. It affects some 8,000 diabetics each year in
this country and is the leading cause of blindness in adults age 20
to 74, according to the American Academy of Ophthalmology.
The early stage of diabetic retinopathy is nonproliferative diabetic
retinopathy (NPDR), which occurs when tiny blood vessels within the
retina leak blood or fluid. The leaking fluid causes the retina to swell
or to form deposits called exudates. Many with diabetes have mild NPDR,
which does not typically affect their vision. When vision is affected,
it is the result of macular edema (swelling of the macula) and/or macular
ischemia (when small blood vessels close). Proliferative diabetic retinopathy
(PDR) is present when abnormal, new vessels (neovascularization) begin
growing on the surface of the retina or optic nerve. Adequate blood
supply is prevented, causing the retina to respond by growing these
new vessels. Unfortunately, the new vessels do not resupply the retina
with normal blood flow, and these new vessels are often accompanied
by scar tissue that may cause wrinkling or detachment of the retina.
PDR causes more severe vision loss when the new vessels bleed into
the vitreous, the clear, jelly-like substance that fills the eye. A
very large hemorrhage might block all vision. Smaller ones cause dark
floaters in one's vision. With time, this new blood in the vitreous
may clear.
A medical eye examination is the only way to find these changes inside
the eye. An ophthalmologist can often diagnose and treat serious retinopathy
before the patient is aware of any problems.
"Our recent studies suggest that rigid control of diabetes dramatically
reduces secondary complications, including eye, kidney, heart and vascular
problems," says Thomas Aaberg, Sr., a leading retina surgeon and director
of the Emory Eye Center. "Rigid control means using an insulin pump
or injecting insulin more than one time a day. Once diabetics have proliferative
retinopathy, tight control will not cause reversal of the problem, but
the disorder is preventable and very treatable with continuous medical
treatment and a yearly exam by an ophthalmologist."
If vision is in jeopardy from nonproliferative retinopathy, Dr. Aaberg
may recommend laser photocoagulation surgery, which seals the leaking
vessels without an incision. Emory participated in two National Institutes
of Health-sponsored studies that showed the procedure can prevent vision
loss by reducing abnormal blood vessel growth and reducing the blood
vessel leakage (edema).
If the vitreous becomes clouded with blood, Dr. Aaberg may rarely recommend
cryotherapy, an outpatient procedure during which a freezing probe is
applied to shrink the abnormal blood vessels. In the most severe cases,
he may suggest a vitrectomy to remove the vitreous humor and replace
it with a clear solution.
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