Continual Monitoring of Fluorescein Angiography

 A system has been developed which enables continuous monitoring and recording of circulating fluorescein in the retinal blood vessels. This is achieved with minimal modification of a Zeiss fundus camera. A night vision television camera (Ikegami) is used with illumination provided by the standard observation light of the fundus camera. This method offers advantages over standard fluorescein angiography in patient comfort, information obtained and the immediate evaluation of the fluorescein angiograms being available.

Checklist and preparation for fluorescein angiography

Checklist and preparation for fluorescein angiography:

1. Informed consent.

2. Inform the patient about fluorescein angiography. Obtain verbal or written informed consent.

3. Dilate patient pupil.

4. Prepare fluorescein solution, vein needle, and syringe.

5. Prepare fundus camera:
a-clean front lens.
b-load color and black-and-white film into two camera backs.
c-focus eyepiece crosshairs.

6. Take identification photograph, which includes the patient name, the date, and other data (number of fluorescein angiogiogram, patient vision of right and left eye, referring physician and so forth)

7. Position the patient for alignment,focus,and comfort.

Fluorescein pathway and timing

Fluorescein pathway:
Arm-to-retina circulation time is 12-15 sec.

angiography dye injection

(Five angiographic phases):

• Pre arterial
• Arterial
• Arteriovenous
• Venous
• Recirculation

BENEFITS OF DIGITAL PHOTOGRAPHY

BENEFITS OF DIGITAL PHOTOGRAPHY:

1. Instant knowledge of image quality
2. Networking of images (a must)
3. Reduction in administration time
4. No film / development costs
5. Easy export for presentations / e.mail
6. Instantly available for viewing
7. Comparison over time on screen
8. Digital image manipulation tools
9. Linkage to Electronic Patient Records
10. Diagnostic Database

patients doesn’t need angiography

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).

Causes of bad quality angiography

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.

• Insufficient Pupil dilatation (at least 6mm) specially with mydriatic cameras.

• Inadequate tear film.

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