PROLIFERATIVE DIABETIC
RETINOPATHY
(PDR)
In PDR, retinal blood vessels close off, and large areas of
retina lose their source of nutrition. When this happens, peripheral or side vision is
usually reduced, and the patient's ability to see at night and to adjust from light to
dark is often diminished.
As a result of this loss of nourishing blood flow, the retina
manufactures abnormal new blood vessels. This is called Neovascularization. This new
vessel growth is the retina's method of coping with the closing off of its own blood
vessels and the loss of nourishment. Many diabetic patients have some closing of retinal
blood vessels without ever developing new vessels. But the problem is that when new blood
vessels do develop, they are never any good; they are, in fact, dangerous to the eye. They
do not nourish the retina properly, and they may cause other problems. One problem is
bleeding into the vitreous cavity (called vitreous hemorrhage). A second problem is the
growth of scar tissue on the retina that can pull the retina off the back wall of the eye
(called a traction retinal detachment). Either of these serious problems, vitreous
hemorrhage or traction retinal detachment, can lead to severe loss of vision or even total
blindness.
It is very important to understand that the closing of retinal
blood vessels and the growth of new blood vessels may occur without any noticeable change
of vision. So, it may be impossible for the person with diabetes and early PDR to know
that such changes are taking place. For this reason, it is essential that every person
with diabetes be examined regularly by a specialist who is familiar with diagnosing
diabetic retinopathy. Such examinations should occur regularly - probably every six to
twelve months, or more or less frequently, depending on the degree of diabetic retinopathy
- for the lifetime of the diabetic patient. The earlier the new vessels are discovered,
the better the chance that laser treatment will save vision. The later the new vessels are
discovered, the greater the chance for blindness.
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