Retinal angiography is simply the imaging of blood vessels of the retina and choroid using dyes injected into the bloodstream. The commonest dyes used are fluorescein and indocyanine green (ICG). They can either be injected separately or together, depending on the reason for the angiogram.
The test consists of a small plastic tube being inserted into a vein in the arm and the dye injected into this. The dye mixes in with the bloodstream and, within 20 seconds, enters the eye. A series of photographs and video is then taken to show which blood vessels fill with blood as well as the pattern and timing of filling and leakage.
The injection of the dye is painless and, with modern cameras, there are no uncomfortable brilliant flashes of light. The results will be available for discussion with Dr Chauhan immediately.
Fluorescein angiography
Fluorescein is an orange-yellow dye with a very low risk of serious allergic reaction. After injection of the dye, about 1 in 50 patients feels a little sick for about 20-30 seconds and then recovers.
All patients’ skin turns yellow for a few hours and their urine becomes bright yellow-green for the rest of the day but there are no long-lasting effects. The chance of a serious allergic reaction is very low, with only around 1 in 220,000 patients experiencing anaphylaxis.
Indocyanine green (ICG) angiography
This is usually used for certain types of age-related macular degeneration. ICG allergy is more common than fluorescein so it is important that you LET THE PERSON PERFORMING THE TEST KNOW IF YOU ARE ALLERGIC TO ICG, IODINE OR SEAFOOD.
ICG has no significant effect on skin or urine colour.