Indocyanine Green Angiography

Generally, strict fasting is not required before indocyanine green angiography (ICG), and it is actually preferable to have had a light meal to reduce the risk of vasovagal episodes. However, it is advisable to avoid a very heavy meal just before the examination. If you have a particular medical history (severe allergies, cardiac or renal conditions, pregnancy), specific instructions may be tailored by your ophthalmologist or general practitioner before scheduling the examination.

The examination is painless from an ocular standpoint: there is no contact with the surface of the eye. The only sensation may come from the venipuncture in the arm, similar to a blood draw. The camera light may seem bright, especially if the pupils are dilated, and the session lasts slightly longer than a simple photograph (approximately 20 to 30 minutes). The vast majority of patients tolerate the examination very well, as it requires no physical effort and is performed in a seated position or slightly reclined in front of the device.

Both examinations use a dye injected into a vein and a specialized camera, but they do not analyze exactly the same structures. Fluorescein primarily explores the superficial retinal vessels, whereas indocyanine green (ICG) penetrates pigments more effectively and highlights the deep choroidal circulation. In practical terms, ICG causes less discoloration of the skin or urine, and images are captured over a slightly longer period. The choice between the two, or their combination, depends on the type of lesion suspected (polypoidal vasculopathy, central serous chorioretinopathy, particular forms of AMD, etc.) and the specific question the physician wishes to answer.

Indocyanine green contains an iodine derivative, which requires particular caution in cases of known iodine allergy or allergy to certain agents injected in radiology. This does not necessarily mean the examination is impossible, but the risk of a reaction must be discussed beforehand, sometimes with specific preparation or the choice of an alternative examination. It is therefore essential to inform your ophthalmologist of any drug allergy, history of shock, or severe adverse reaction after an injection, so that the benefit-risk ratio can be assessed and the procedure can be carried out safely if it remains necessary for your care.

If the pupils have been dilated, vision may be blurred and sensitive to glare for a few hours. In that case, it is advisable not to drive immediately after the examination and to avoid visually demanding tasks (prolonged reading, detailed screen work). Normal physical activities can generally be resumed quickly. In practice, many patients arrange to come with a companion or use public transportation, then resume their professional activities the next day or later in the day once vision becomes comfortable again.

Indocyanine green angiography is not an examination that needs to be repeated systematically at fixed intervals. It is primarily performed at the time of initial diagnosis or when a change in disease course or treatment is suspected (change in OCT appearance, new visual decline, suspicion of polyp recurrence or lesion extension). For routine follow-up, OCT and, if needed, OCT angiography are often sufficient. The physician therefore recommends repeating ICG only when the expected information could concretely alter the therapeutic strategy (injections, targeted laser, intensified monitoring, etc.).

As a general rule, indocyanine green angiography is avoided during pregnancy, except in exceptional situations where the visual stakes are significant and no other examination can provide the necessary information. Breastfeeding is not an absolute contraindication, but additional precautions may be discussed (for example, pumping and discarding breast milk for a short period after the examination). In all cases, it is essential to inform your ophthalmologist if you are pregnant, planning a pregnancy, or breastfeeding, so that the imaging strategy can be best adapted to your situation.