DIABETES AND YOUR EYES
By David Mallory M.D.
Twelve million Americans have diabetes. For everyone
diagnosed as diabetic, there is one undiagnosed who does not
know that he or she has this condition.
Although the incidence of cataracts is five times as high
and glaucoma is twice as high in diabetics, it is the effect
of diabetes on the retina that causes the most damage. The
retina lines the inside of the eye and is the actual
"seeing" part of the eye.
Diabetic retinopathy is the leading cause of blindness in
adults younger than age 65.
Diabetes attacks the tiniest blood vessels in the retina,
called capillaries, causing them to leak fluid (edema) and
become brittle or sclerotic and close up. There are two
treatable and possibly preventable reasons why eyes can lose
vision in diabetes.
The first is from swelling in the central vision area of the
retina, called the macula. The second is from bleeding into
the eye from fragile new blood vessels caused by not enough
oxygen getting to the retina.
Two large national studies have shown that laser
photocoagulation can dramatically decrease the incidence of
visual loss in diabetes. The first was completed in 1979 and
showed a 50 to 65 percent decrease in severe visual loss in
high risk diabetic patients who had new blood vessel growth
into the eye, but early diagnosis and treatment were found
to be critical.
Another study also emphasized the importance of early
treatment. People with diabetes may develop swelling in the
macula, the part of the retina that specializes in seeing
small things. They may have edema even if their vision is
20/20 and they have no visual complaints. Treatment of the
swelling with a laser over a three-year period cut loss of
vision in half, from 24 to 12 percent. Very few patients,
however, were able to recover vision already lost.
The possibility of retinal problems from diabetes increases
with how long the person has been diabetic and how well
their blood sugar has been controlled. High blood pressure
and perhaps smoking have been shown to make the retinopathy
worse. Some studies have shown Mexican Americans to be at
It is important that people with diabetes know that they may
have retinal problems that are sight threatening, even
though they seem to have no visual problems. When they do
occur, it may be too late to restore full vision or to stop
further deterioration with laser photocoagulation. Early
detection depends on regular, thorough eye examinations.
David Mallory, M.D. is a cataract, intraocular lens and
laser surgery specialist in practice at the Southwest Eye