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Indocyanine Green Dye Study
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The "hot spot"
is indicated by the white (hyperfluorescent) area. (arrow)
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An Indocyanine Green study (ICG) is a special dye test used to evaluate the circulatory system of the choroid, the layer just behind the retina. ICG reacts to light with a longer wavelength than fluorescein dye, allowing the doctor to pinpoint the location of leaking vessels deeper within the eye that may not be apparent with fluorescein angiography.
After the ICG is injected into the patient’s arm, it travels through the bloodstream to the eye in about 15 to 20 seconds. Once it reaches the eye, it illuminates the leaking vessels or “hot spots” in the choroid. Using a digital camera equipped with a special filter, the retinal photographer takes photos as the dye travels through the vessels in the eye.
The doctor interprets the digital photos and determines whether treatment is needed. If there is an active leak, the photos serve as a guide to seal the vessel with laser. The ICG study helps the doctor target the leak with greater accuracy, reducing the risk of damage to surrounding retinal tissue.
The risk of allergic reaction to the dye is very minimal; however, it cannot be performed if the patient is allergic to shellfish or iodine.
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