Evaluations and Diagnostic Tests
Angiostatic Steroids
The investigational use of angiostatic steroids to control the growth and leakage of abnormal
blood vessels (choroidal neovascularization) under the macula is currently underway at Wills Eye.
Researchers have found that certain drugs can inhibit blood vessel growth. One of these drugs,
anecortave acetate is being studied to see if its "angiostatic" properties can be applied to macular
disease. For more information, click on clinical trials of the Wills Eye Retina Service.
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Fluorescein Angiography
Fluorescein angiography, a clinical test to look at blood circulation inside the back of the eye, aids
in the diagnosis of retinal conditions associated with diabetes, age-related macular degeneration, and
other eye abnormalities. The test can also help monitor the course of a disease and its treatment. It
may be repeated on multiple occasions.
Fluorescein, an orange-red dye, is injected into a vein in the arm. The dye travels through the body
to the blood vessels in the retina. A special camera with a filter flashes a blue light into the eye
and takes multiple photographs of the retina. No X-rays are involved.
If there are abnormal blood vessels, the dye leaks into the retina or stains the blood vessels. Damage
to the lining of the retina or atypical new blood vessels may be revealed as well. These abnormalities
are determined through a careful interpretation of the photographs by an ophthalmologist.
The dye can discolor skin and urine until it is removed from the body by the kidneys. There is little
risk in having fluorescein angiography, though some people may have mild allergic reactions to the dye.
Severe allergic reactions do occur.. Being allergic to X-ray dyes with iodine does not mean you'll be
allergic to fluorescein. Occasionally, some of the dye leaks out of the vein at the injection site,
causing a slight burning sensation because of the salt that is in the dye.
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Indocyanine Green Angiography (ICG)
ICG angiography is a clinical test used to detect abnormal blood vessels in the choroid, the layer of
blood vessels under the retina. These abnormal blood vessels, typically associated with macular
degeneration, may cause bleeding, scarring, and vision loss. If the blood vessels can be cauterized
by laser surgery, vision loss may be stabilized or improved.
Indocyanine, gives off infrared light. When injected into the bloodstream, the dye travels through
the veins to the blood vessels in the eye. A video camera connected to a computer picks up the
infrared light and makes a picture of the blood's circulation. No film or x-rays are involved.
Following the test, the liver removes the dye.
People allergic to shellfish or iodine should not have this test.
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Photodynamic Therapy
The only proven treatment currently available for the "wet" form of age-related macular degeneration
(AMD) is laser photocoagulation, but a number of patients with this condition are not candidates for
the procedure due to the location and type of leakage they are experiencing. However, researchers at
Wills Eye are participating in national studies on new treatments for AMD, including the use of
photodynamic therapy.
The Wills Eye Retina Service is conducting clinical trials on photodynamic therapy, which uses a
combination of a dye-like substance and laser to reduce the leaking from abnormal vessels (choroidal
neovascularization) under the macula.
In photodynamic therapy, the patient is injected with verteporphin, which selectively collects in the
abnormal leaking vessels under the fovea, the part of the eye that is responsible for our color vision
and ability to see detail. A non-thermal laser is then used to "activate" the dye in the leaky
vessels. Because the laser used in photodynamic therapy is less intense than that used for laser
photocoagulation, this investigational treatment is believed to prevent damage to the retina and
fovea.
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Transpupillary Thermotherapy
Transpupillary thermotherapy (TTT) being investigated as a possible treatment for macular disease.
This procedure involves the use of a special lens that is placed over the cornea. A laser beam is
then passed through the lens to treat leaking vessels.
The Wills Eye Retina Service is participating in clinical trials to evaluate TTT.
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