By
Jonathan Yoken, MD
DIABETIC
RETINOPATHY
What
is diabetic retinopathy?
Diabetes has
damaging effects on blood vessels all over the body. When the
blood vessels that support the retina become damaged, they may
leak fluid, bleed or lead to the growth of scar tissue. All of
these changes can cause blurring, distortion or even loss of vision.
The severity
of diabetic retinopathy is dependent on the length of time a person
has had diabetes and the quality of one's blood sugar control.
Type 1 diabetics who have juvenile diabetes tend to have retinopathy
at younger ages. Those individuals with poor blood glucose control
also have increased risk of retinopathy.
Even though
diabetic retinopathy is the leading cause of new blindness in
adults in the United States, with improved diagnosis and treatment,
only a small percentage of people who develop diabetic retinopathy
will go on to develop severe vision loss.
What
are the different types of diabetic retinopathy?
Background
retinopathy
This is an
early form of the disease, and it is also the most common. In
this stage, the blood vessels within the retina have started to
leak fluid and bleed. The accumulation of fluid in the retina
causes it to swell. The blood vessels also leak cholesterol-like
material, called exudates, into the surrounding retina.
Depending on how severe the leakage is and where in the retina
the damage or swelling occurs, will determine the effect it has
on the vision. When the swelling occurs in the macula, the center
part of the retina, this can cause changes in the central vision.
This is called macular edema.
Proliferative
retinopathy
When the normal
blood vessels of the retina become so damaged that they can no
longer bring enough fresh oxygen to the retina, the eye will try
to grow new blood vessels to replace the damaged ones. This process
is called neovascularization. Unfortunately, when the eye
tries to grow new blood vessels, they grow upon any surface, including
the retina and into the jelly, called the vitreous, which
fills the center of the eye. These vessels have very fragile walls
that may break and bleed. This bleeding can cause massive floaters
and block all or part of the vision. Occasionally, as the blood
vessels break and bleed, they convert into strands of scar tissue,
which can pull on the retina and cause a retinal detachment.
A retinal detachment is a serious ocular condition that often
requires surgery to correct.
Sometimes
the blood vessels will grow in the front of the eye and block
off the drain. This causes the pressure within the eye to rise,
which is a type of glaucoma (neovascular glaucoma).
How
is diabetic retinopathy diagnosed?
It is very
important that you have at least an annual eye exam, and more
frequent exams if recommended by your eye doctor. In order to
detect retinopathy, particularly at its earliest stages when there
may be no visual symptoms, a complete eye exam, including pupil
dilation, must be performed. When retinopathy is detected, other
tests may be needed in order to determine if you require treatment.
One of these tests requires that you receive a dye injection in
order to study the blood vessels in the retina. This test is called
a fluorescein angiogram.
How
is diabetic retinopathy be treated?
Treatment
depends primarily upon the type and severity of the retinopathy.
The most important aspect of treatment, however, is prevention.
By keeping your blood glucose under tight control, and paying
attention to diet and exercise, you can significantly reduce your
chances of developing retinopathy.
Laser surgery
Although it
is called surgery, it does not involve any cutting of the skin
or eye. It is performed by directing a beam of light into the
eye to treat the damaged parts of the retina. In cases of background
diabetic retinopathy with macular edema, the laser is used to
seal off leaking blood vessels and to stimulate the eye to reabsorb
the fluid and exudates. When abnormal blood vessel growth is present,
as in proliferative diabetic retinopathy, laser is used to treat
the peripheral retina. This in turn decreases the blood vessel
growth and welds the retina to the wall of the eye, which can
help prevent a retinal detachment. Laser surgery is often performed
in the office and usually only requires topical or local anesthesia.
Cryotherapy
When the eye
is filled with blood from abnormal vessels, and the view into
the eye is too clouded to treat with laser. Cryotherapy can be
used to administer a freezing burn through the outside wall of
the eye to achieve the same effects as laser.
Vitrectomy
Vitrectomy
surgery involves removing the vitreous gel from the center of
the eye and replacing it with clear fluid. In cases where the
vitreous is filled with blood and several months have passed without
spontaneous clearing, surgery may be recommended to speed healing
and restoration of the vision. Your eye can function normally
without the vitreous. Even though the blood may be severely impairing
your vision, your doctor may advise waiting to see if the blood
clears on its own before recommending surgery, particularly if
you can see well with your other eye. Vitrectomy surgery is also
performed to repair retinal detachments caused by excessive scar
tissue that develops in proliferative retinopathy.
Early detection
of diabetic retinopathy is the best way to prevent vision loss.
With careful monitoring, treatment can often be initiated before
your vision is affected. The available treatments are highly effective,
but are best when combined with healthy lifestyle habits
