An Indocyanine green angiography, ICG for short, or also known as a choroidal angiography is a diagnostic test used to take images of the choroid, the layer of blood vessels and connective tissues between the sclera and the retina.The images produced by an ICG are used to help ophthalmologists diagnose and monitor retinal diseases and disorders such as wet age-related macular degeneration, uveitis,and tumours.
Similar to a fluorescein angiography, an ICG allows ophthalmologists to take images of the blood vessels within the choroidal layer using a special dye that can be visualized within the infrared spectrum using a diagnostic camera. Under normal circumstances, this layer is not visible, but with an ICG, an ophthalmologist can assess how blood is flowing through these vessels and determine the presence of blockages or leaks.
At the beginning of an ICG, the patient’s pupils will be dilated using eye drops. A series of photos will be taken using a special diagnostic camera before the dye is injected into the arm. Once the dye is injected, it will pass through the blood stream and through the vessels within the choroid. Since this dye is appears visible in the infrared spectrum, it will appear visible to the diagnostic camera, which allows images to be taken showing where blockages or leaks are occurring.
Patients may feel mild nausea, dizziness, or headachesafter being injected with the dye, but this feeling will go away within a few minutes. Some patients have a reaction to the dye and develop itchiness or a rash where the dye was injected into the arm. Medication to treat these symptoms can be provided by your retinal specialist.
This diagnostic test takes approximately 60 minutes to complete.Patients will need to arrange someone to pick them up following an ICG, as their pupils will be dilated and sensitive to light for up to 12 hours after the test is performed.
Information collected during the examination is recorded by Calgary Retina Consultants and saved in the patient’s records for future use. All patient records are strictly confidential.