Fundus Fluorescein Angiography (FFA), eye angiogram

Fluorescence :

is a property of substance to alter the wave length of the reflected light on exciting. Angiography means recording of the angios or the blood vessels. It is basically recording and visualization of the blood vessels of the retina using fluorescein dye.

Characteristics of Fluorescein :

Nontoxic, inexpensive, safe
Alkaline solution
Highly fluorescent
Absorbs blue light (480-500 nm)
Emits yellow-green (500-600 nm [525 nm])
Effective at pH 7.37-7.45
Removal from blood by kidneys and liver within 24 hrs.

During Pregnancy and Lactation :

Controversial
Fl. Crosses the placenta
Has been done in pregnancy with no adverse effect
Do it when necessary
Fluorescein is secreted in milk.

fluorescein dye arm injection

General overview on Procedure :

In FFA, the chemical or dye is injected in the vein of the hand and this dye circulates all over the body and in every blood vessel. Since retina is the only place in the body where blood vessels can be seen, it is used to visualize the retinal vasculature, that is blood vessels of the retina.
A special machine called the fundus camera, which has got special lens filters, is used to take photographs of the retina. We can also attach digital camera system or a printer.
When blue light falls on retina which has Fluorescein dye the reflected light is of green colour & not blue. This property of dye is used to study the normal or abnormal anatomy of retina. This dye and the reflected light is greenish in color. The fundus camera records this. This dye would go wherever the blood vessels are present in retina and we would get the picture of that.

If blood vasculature of the retina is normal, then we would get the normal pattern of the retina. If there were blockage then the dye would not go beyond that and would stop at that particular point. If there is leakage, the dye would also leak out along with the blood in the retina and we would be able to pick up that. If there are certain other defects in the retina then depending on the various features seen, whether we get leakages or staining or blocked fluorescence or window defects whether the dye seen in early phase, late phase or in very late phase or delayed phase and is initially less and increasing etc, we can get very good idea of patients disease.

retinal angiography procedure

Checklist and preparation for fluorescein angiography:

click this post Checklist and preparation for fluorescein angiography

here is a video showing the process:
 

Stages:
1• series of colour photographs are taken of the back of your eye.

2•A small needle is inserted into a vein in your arm or hand.

3• The lights will be turned off and the dye injected.

4• Once the dye reaches the back of the eye, (this only takes a few seconds), the photographer will begin to take lots of pictures.
5• The lights from the camera flash are quite bright but it is very important to keep your eye open, a nurse will help you if necessary. You will then have a short rest.

6• Another series of photographs will then be taken a few minutes later. The needle will then be removed and you will be asked to wait in the waiting area for about 15 minutes.
7• You will usually be given another appointment to discuss the results and plan your treatment with the eye doctor, although this is sometimes possible on the same day as the test.


Fluorescein pathway:
Arm-to-retina circulation time is 12-15 sec.
(Five angiographic phases):

• Pre arterial
• Arterial
• Arteriovenous
• Venous
• Recirculation

Causes of bad quality angiography :
• Speed of dye injection (2-5 sec)
• Ocular media opacities (cataract , vitreous
hemorrhage , corneal scar)
• Patient movement (image out of focus)
• Dust on the camera
• The film (out of date)
• Problem in print process
• Pupil dilatation (at least 6mm)
• Adequate tear film

When the patients doesn’t need angiography:

• AMD doesn’t need treatment : disciform scar, geographic atrophy , senile derusen , atrophic scar after PDT.

• Choroidal melanoma.

• Retinal vascular obstruction only in retinal vein occlusion after 3 months for laser treatment.

• Congenital retinal dystrophy (fundus autofluoresence is preferable).