Indocyanine Green Angiography (ICG) is a diagnostic procedure that uses ICG dye to examine the blood flow in the CHOROID &#; the layer of blood vessels which lies underneath the retina.
Link to weiqing
Indocyanine Green dye is injected into a vein in the arm/hand. As the dye passes through the blood vessels of your eye, photographs are taken to record the blood flow.
The choroidal vessels are hidden beneath a layer of pigmented cells. Infrared light given off by ICG dye can be imaged through the pigmented layer using special filters.
The most common application of indocyanine green angiography is the detection of choroidal neovascularization, a common component of age related macular degeneration.
In multiple inflammatory conditions, as well as with central serous chorioretinopathy, distinct ICG patterns have emerged that may facilitate better understanding of the disease processes.
The actual procedure will take 10-20 minutes. The average length of stay in our department can be 1-2 hours.
The Indocyanine Green dye is generally tolerated without any problems. However, ICG dye contains iodine. Severe allergic reactions are possible in people who are allergic to iodine. Our nurse will review your medical history to ensure you are not allergic to substances that contain iodine, such as x-ray dyes and shellfish. ICG dye does not cause urine or skin discoloration.
Your pupils will be dilated for the ICG.
After the pupils are dilated your vision may become blurred. Driving is not recommended when your pupils are dilated.
EAT, DRINK & TAKE your medications as you usually do.
DRINK an extra 2-3 cups of water before the procedure.
AVOID coffee, tea, or caffeinated beverages.
For more information, please visit Retinal Camera.
BRING an English translator.
BRING your lens case, if you wear contact lenses, as you will need to remove the contacts.
ICGA has a safer side effect profile compared to FA. Moderate side effects have been reported at a rate of 1:63, serious side effects at a rate of 1:, and death at a rate of 1: after FA.26
Adverse effects after the use of ICG are rare. Rates of mild, moderate, and severe reactions have been reported as 0.15%, 0.02%, and 0.05-0.07%, respectively.27,28
ICG dye contains up to 5% sodium iodide as an additive to prevent recrystallization. Therefore, caution should be exercised considering the potential side effects in patients with thyroid hyperfunction. Thyroid function tests performed after ICGA give inaccurate results. On the other hand, it is argued that since iodine is naturally found in the human body, there can be no risk of antibody formation or the development of an immune-mediated allergic reaction against it.29 The allergies that develop after consuming shellfish and other seafood are attributed to the proteins in the food, not the iodine.30
The cause of side effects following ICGA has not been fully explained. Non-allergic histamine release due to iodine or ICG, IgE-mediated hypersensitivity, complement system activation, or the release of other inflammation mediators are suggested mechanisms.31
Moreover, although very rare, adequate preparation is necessary in the event of anaphylactic shock after ICG injection.32
ICG dye can also be prepared without the addition of iodine, but severe side effects have also been reported after iodine-free ICGA.33
As ICG separates bilirubin from protein in in vitro studies, it should not be administered to preterm infants and neonates who require transfusion due to hyperbilirubinemia. The indication should also be reviewed in patients with uremia, severe liver failure, or a history of severe multiple allergy (Table 2).3
Table 2
Table 2. Contraindications of indocyanine green angiography
It has been reported that ICG shows minimal passage across the placenta and that the placenta has a protective effect against its passage to the fetus.34 Although there is no proven teratogenic effect, its indication for use in pregnancy should be carefully discussed.
Non-specific side effects following angiographic dye delivery are usually recorded as allergic reactions. This leads to the restriction of new angiographic examinations needed in the future. For this reason, it is important to reevaluate a patient&#;s history of post-angiography side effects and other possible factors in detail.