WHAT IS IT?
Angiography in general is an image test that allows visualizing the blood vessels and requires substances of contrast, when circulating by them, allow the observation of their form, thickness, tracing and permeability. A fluorescein angiography is actually an angiogram but performed on the network of vessels in the fundus of the eye (retina) and with a special coloring substance called fluorescein (red-orange).
Fluorescein angiography is a process of diagnosis, using a camera to special optical high sensitivity that captures fluorescence. Allowing a series of photographs as a contrast called fluorescein or indocyanine green. That flowing through the veins and arteries of the retina and choroid. In this way perfectly looks like blood circulates in the Fluorescein, and to diagnose vascular defects that affect the retina or choroid.
Why is a fluorescent substance used?
This type of angiography does not use X-rays, like the other angiographies, because the image is photographed directly thanks to the fluorescence light of the substance used and network of vessels of the retina is the only part of the circulatory tree that we can see directly. That is why no radiation is needed that penetrate the interior of the body, such as x-rays or others.
How is this test performed?
The test takes about 20 minutes and is quite simple. It consists of administering a mydriatic (substance that dilates the pupil) to the patient and placing it in front of a device (slit chamber) that fixes the head by supporting the chin and forehead in it, and allows us to observe in detail the background of the globe Ocular (retina). The patient should be completely still trying not to move or blink.
When we see the back of the eye, we inject the fluorescein into a vein in the arm, waiting for it to spread throughout the circulatory system, which happens in a matter of minutes. When the substance reaches the eyes, serial images are taken photographically of the progressive filling of the retinal vessels with this substance. It is also possible to do the test without injecting the dye. To do this, the patient is given capsules with fluorescein (one of 500mg per 15 kilos in weight) about 30-45 minutes before the test. The modality finally used (injected or oral) will depend on the protocol and custom of each health center.
What types of diseases can be diagnosed with this test?
Fluorescein angiography allows us to see if there is any obstruction in any blood vessel in the fundus of the eye (retinal thrombosis) or if there are abnormal forms or tracings of the retinal arteries. It is also extremely useful for diagnosing eye diseases such as macular degeneration (severe deterioration of the central retina), retinal detachment, retinal microaneurysms (abnormal dilatations of retinal vessels), or certain complications of certain diseases, Such as diabetes (diabetic retinopathy) or hypertension (hypertensive retinopathy).
What happens after the test?
In patients who do not have severe kidney problems the fluorescein will be eliminated by the kidney without major problem in the course of a day. Do not be scared of the color of the urine, which acquires a yellow-green color due to the substance. On the other hand it is advisable to avoid direct exposition to the sun during the 24 hours following the test, because fluorescein is a substance that can photosensitize the skin and produce spots on it.
WHAT DISEASE DETECT?
It is used to detect and assess the vascular status of Retinal and Choroidal, which is we see in the Fundus. Among others it is useful in the following situations:
Diabetic Retinopathy: Diabetes is one of the most important causes of blindness in the developed world, it causes damage to blood vessels in the retina, which allows angiographic follow laser treatment to prevent bleeding and visual loss.
Related Macular Degeneration (ARMD), allows you to decide which type of therapy should be administered, as a dry or atrophic AMD, and wet or exudative.
Retinal Vascular occlusions or thrombosis and embolism, edema of the macula (cystoid macular edema), Central Serous chorioretinopathy, and other diseases Retinal.
What are the risks of angiography?
Fluorescein and indocyanine green, is a safe drug, but after the solution injected, skin and urine can become yellowed, while the solution is eliminated by the kidneys. Some people may have nausea during the procedure disappear quickly.
In some cases it may produce nausea, a sore throat, or a rare taste when injected with fluorescein, but such symptoms usually do not matter. The test is not of special risk, except in the case of a significant allergy to fluorescein, which is very rare, fortunately.
There may be allergic reactions, and rarely anaphylactic shock occur, so any allergies should be reported to your doctor before testing.
The information and /or answers in this article only general information purpose & not for practicing or taking any decision without any ophthalmologist. Only a doctor can diagnose and treat a medical condition or disease.
- What Is a Fluorescein Angiography?
- Fluorescein angiography is an eye test
- Retinal Imaging
- American Academy of Ophthalmology