Angiofluoresceingraphy . Imaging test that allows visualizing blood vessels and requires contrast substances that, when circulating through them, allow the observation of their shape, thickness, tracing and permeability. An angiofluoresceingraphy is really an angiography but performed on the network of vessels of the fundus of the eye ( retina ) and with a special coloring substance called fluorescein (red-orange color) allows to see the vessels of the fundus.
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- 1 Description of the test
- 1 Why is a fluorescent substance used?
- 2 How this test is performed
- 2 Diseases that are diagnosed
- 3 After the test
- 4 Risks
- 5 Source
Angiography is a diagnostic test, with which we obtain photographs of the retina. It is done to diagnose diseases or problems in the retina. In this procedure it is necessary to inject a contrast medium to obtain the photographic images. Fluorescein Sodium is injected to view the vascular system of the retina. The examination requires previous pupillary dilation and the procedure lasts 20 minutes with fluorescein.
Why is a fluorescent substance used?
This type of angiography does not use X-rays , like the other angiographs, because the image is photographed directly thanks to the fluorescence light of the substance used and because the retinal vessel network is the only part of the circulatory tree that is you can see directly. Therefore, radiation that penetrates into the body is not required, such as X-rays or others.
How this test is performed
The test lasts about 20 minutes and is simple. It consists of administering a mydriatic (substance that dilates the pupil) to the patient and placing it in front of an apparatus (slit chamber) that fixes the head by supporting the chin and the forehead on it, and which allows us to observe in detail the bottom of the balloon ocular (retina). The patient must be completely still trying not to move his eyes or blink.
When the bottom of the eye is seen, fluorescein is injected into a vein in the arm , waiting for it to spread throughout the circulatory system, which happens in a matter of a few minutes. When the substance reaches the eyes, serial images of the progressive filling of the retinal vessels with said substance are taken photographically. There is also the possibility of doing the test without injecting the dye. For this, the patient is given some capsules with fluorescein (one of 500mg for every 15 kilos of weight) about 30-45 minutes before doing the test. The modality finally used (injected or oral) will depend on the protocol and custom of each health center.
Diseases that are diagnosed
The angiofluoresceingrafía allows to see if there is any obstruction in any blood vessel at the bottom of the eye ( retinal thrombosis ) or if there are abnormal forms or lines of the retinal arteries. It is also extremely useful for diagnosing eye diseases such as macular degeneration (severe deterioration of the central area of the retina), retinal detachment , retinal microaneurysms (abnormal dilatations of the retinal vessels), or certain complications of certain diseases, such as diabetes (diabetic retinopathy) or hypertension (hypertensive retinopathy). <
After the test
In patients who do not have severe kidney problems, fluorescein will be eliminated by the kidney without major problems in the course of a day. The color of the urine will be greenish-yellow due to the substance. On the other hand, it is advisable to avoid exposing yourself directly to the sun for 24 hours after the test, since fluorescein is a substance that can photosensitize the skin and cause spots on it.
In some cases it may cause nausea , an itchy throat or a strange taste when injecting fluorescein, but such symptoms are usually not important. The test is not particularly risky, except if you have a severe allergy to fluorescein, which is very rare.