Diabetic Eye Disease
Diabetes is the number one cause of new blindness in the United States for people
under the age of 65. When one thinks of diabetes, one usually thinks about the body's
ability to control sugar. Although this is certainly a part of the disease, diabetes is
primarily a disease that affects blood vessels and circulation. Diabetes has many
different effects on the eye. Cataracts, glaucoma and retinal disease can all be brought
on by diabetes.
A cataract is the progressive clouding of the lens inside the
eye. Cataracts are usually associated with aging, but diabetes can make cataracts develop
sooner than they would otherwise. There are different types of cataracts. One particular
type that is associated with diabetes is called a posterior subcapsular cataract. This
type of cataract tends to occur in younger people and will progress much more rapidly that
the typical type of age-related cataract.
Glaucoma is the disease where pressure builds up inside the eye
and causes permanent nerve damage. People with diabetes are much more likely to develop
glaucoma than people without diabetes. There is actually a genetic link between diabetes
and glaucoma. When diabetic eye disease gets to advanced stages, an unusual type of
"secondary glaucoma" can develop. This condition, called rubeotic glaucoma,
occurs in response to severe effects of diabetes on the circulation inside the eye.
Rubeotic glaucoma can cause permanent damage to the eye within days of developing.
The biggest problem that diabetes causes in the eye is DIABETIC RETINOPATHY. This is a
disease of the retina, the nerve layer that lines the
inside of the back of the eye. The first signs of diabetic retinopathy come when the blood
vessels inside the retina become "leaky". These blood vessels leak fluids that
cause the retina to become swollen. As the retina swells, vision gets worse. This is
called background diabetic retinopathy. Ophthalmologists can actually see this swelling
when they examine the eye. When the swelling involves the center of vision, LASER surgery is performed to seal off the leaking areas.
If the leakage is stopped, good vision remains. In more severe stages of the disease, the
small blood vessels inside the eye begin to close down. In response to the lack of
circulation, new blood vessels begin to grow. This is called proliferative diabetic
retinopathy. These blood vessels are abnormal and cause more harm than good. They are
prone to breaking and bleeding. If they do, sudden, severe loss of vision results. These
blood vessels also lead to the formation of scar tissue that can cause retinal
detachments. Fortunately, LASER surgery is also very effective in causing these abnormal
blood vessels to shrink away and disappear.
Diabetic eye disease tends to worsen with time. The longer one has diabetes, the
greater the risk of developing these conditions. Recent studies have shown that the risks
of developing the complications of diabetes are related to how well the diabetic controls
his or her blood sugar. The better the sugar is controlled, the less the likelihood of
complications.
Ophthalmologists are fortunate in that we can see actual blood vessels inside the
body. The changes that we see in the blood vessels of the eye of a diabetic are also
occurring elsewhere in the body. If there is significant damage to the blood supply inside
the eye, it is very likely that the same changes are occurring in the individual's heart,
kidneys, brain and other major organs.
Aggressive, early treatment of diabetic eye disease has been shown to prevent loss of
vision. All diabetics need to be examined by an ophthalmologist at least once each year so
that these problems can be detected and treated before they cause permanent vision damage.
Copyright, 1997. Richard E. Gans, M. D.
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