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When you visit your ophthalmologist,
he or she may need to take special photographs
of your retina,
the light-sensitive layer of cells
lining the back of your eye.
The retina is responsible for detecting light
which, in turn, allows you to see.
The process of taking photos of the back of your eye
is called angiography.
Angiography helps your ophthalmologist
see what is happening in the retina
or in the blood vessels under the retina called the choroid.
Ophthalmologists use angiography to help diagnose and monitor
certain eye conditions such as diabetic retinopathy
and macular degeneration, among others.
Also, if you're going to have laser surgery on your retina,
your ophthalmologist may use angiography
to help guide the laser with pinpoint accuracy.
After laser surgery, angiography may be used
to help monitor the effect of the laser procedure.
With angiography, a colored dye is injected
into a vein in your arm or in your hand
where it travels throughout the blood vessels in your body.
As the dye passes through the eye's blood vessels,
a special camera takes photographs
of the retina or choroid blood vessels.
These images allow your doctor to see if there are
abnormal blood vessels in or under the retina.
If you have symptoms such as blurred or distorted vision,
your ophthalmologist can locate any leaking blood vessels
in the retina that may be causing these symptoms.
Blurry or distorted vision are the hallmarks
of common eye diseases such as macular degeneration
or diabetic retinopathy.
Angiography can show if there's any blockage
in retinal blood vessels.
It can also help show swelling or tumors in the eye.
Your ophthalmologist also uses angiography
to precisely locate areas of the retina
to be treated with laser eye surgery.
Two types of dyes can be injected into the vein.
One dye is called fluorescein, which is bright yellow.
Fluorescein angiography is the best way
to examine the blood vessels in the retina.
The best way to see the choroidal blood vessels
is with indocyanine green, or ICG dye.
This is because the choroidal blood vessels
are hidden beneath a layer of colored cells in the retina.
With ICG angiography, light released by the ICG dye
can be seen through the colored cells.
When you are going to have angiography,
special eye drops are put into your eyes
to make your pupil dilate, or widen.
Then your ophthalmologist or an assistant
will insert a very thin needle into a vein in your arm
and inject the dye.
As the dye passes through the blood vessels
in the retina and choroid,
a special camera will take a series of photographs
to be reviewed by your ophthalmologist.
The entire procedure usually takes less than 20 minutes.
If the dye leaks from your vein,
a burning sensation may occur on the skin at that site.
Because your pupils have been dilated,
your eyes may be sensitive to light.
Bring sunglasses with you to your appointment
to help with glare and light sensitivity
when you leave the office.
Also, your vision will probably be blurry
after dilation, so it's a good idea
to have someone drive you home afterwards.
Your vision may appear darker or have a colored tint
after the procedure.
This will last only a few minutes.
After the fluorescein dye is injected,
your skin may turn yellowish for several hours.
And also, because your kidneys remove the dye from your body,
your urine will turn dark orange or yellow
for up to 24 hours following the test.
Some people may feel tired, lightheaded, or nauseous
after having the dye injected.
Also possible are vomiting, headache,
fainting, itching, or hives.
Alert your ophthalmologist
if you experience any
of these side effects.
Rarely, people may have an allergic reaction
to fluorescein dye such as a skin rash or itchy skin.
Severe reactions are very uncommon
but could include trouble breathing.
This rare occurrence would be treated
with antihistamine drugs as needed.
Be sure to tell your ophthalmologist
if you have asthma or breathing problems.
ICG dye contains iodine.
Iodine is also found in shellfish
and in the substance used in contrast x-rays.
People who are allergic to iodine may have
severe allergic reactions to ICG dye.
If you are allergic to shellfish
or if you've had a reaction to medical dyes in the past,
be sure to tell your ophthalmologist.
Many potentially blinding eye diseases,
such as diabetic retinopathy,
are only diagnosed through complete medical eye exams.
Your ophthalmologist may rely on angiography
to find where problems may exist
or to help guide and monitor treatment.
If you have any questions about angiography,
be sure to talk with your ophthalmologist.
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